- Email: [email protected]
Manipulating the immune response; applications in livestock breeding
Journal of Reproductive Immunology 57 (2002) 239–253 www.elsevier.com/locate/jreprimm
Manipulating the immune response; applications in livestock breeding Shari Lofthouse *, Joanna Kemp Centre for Animal Biotechnology, School of Veterinary Science, The Uni6ersity of Melbourne, 3010, Vic., Australia
Abstract There are many opportunities for the use of immune modulation techniques in livestock that offer the potential to reduce the requirements for chemical usage and surgical intervention in standard management practices. While vaccination has been used for many years for disease control, there are areas in which vaccination has not been very successful, including the induction of mucosal responses, the induction of cellular responses, and the ability to induce extended duration of protection after a single administration of antigen. In addition, new areas of immunological intervention such as immunisation against reproductive hormones offer new opportunities to modify not only reproductive performance, but also growth, metabolism, carcass quality and behaviour in livestock. These new techniques bring increased need for enhanced efficacy and duration of response. While extensive studies in vaccination have shown that many of the desired immunological responses can be induced in experimental conditions, effective application in the field is dependent upon the development of vaccine delivery methods that are practical within the confines of an effective livestock management system. This paper outlines restrictions that may be imposed on vaccine delivery to livestock and introduces controlled antigen delivery as a potential method for single dose vaccination. © 2002 Published by Elsevier Science Ireland Ltd. Keywords: Immune modulation; Controlled release; Vaccine deliver; Vaccination
* Corresponding author. Fax: + 61-3-9347-4083. E-mail address: [email protected] (S. Lofthouse). 0165-0378/02/$ - see front matter © 2002 Published by Elsevier Science Ireland Ltd. PII: S 0 1 6 5 - 0 3 7 8 ( 0 2 ) 0 0 0 0 6 - 2
240
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
1. Introduction Traditional approaches in livestock production have employed procedures such as surgical intervention and chemical treatment for control of pests, diseases and fertility. These methods often induce undue stresses on stock and result in chemical residues adversely affecting meat, milk or wool quality. Immune intervention offers excellent potential for manipulation of livestock production with minimal invasive treatments, resulting in reduced stress, reduced labour costs and increased animal production. Recent advances in immunology have extended the capacities of vaccination beyond the classical use for disease control, and it is now possible to intervene in many physiological functions. Although there are potential benefits arising from use of these technologies, their successful application in industry is dependent on methods of vaccination that provide responses of sufficient magnitude and duration and resulting in the appropriate immune phenotype. Careful selection of vaccine delivery method, the use of appropriate adjuvants and the application of novel methods of controlled antigen delivery are currently being used to meet these aims.
2. Vaccination for pathogen and parasite control Vaccination remains the most cost-effective method of disease control. Its use in livestock was first demonstrated by Louis Pasteur in the late 1800s using a Pasteurella multocida vaccine for fowl cholera (Pasteur, 1880) and an anthrax vaccine for sheep (Pasteur et al., 1881). Despite over 100 years of vaccine development, attenuated and/or killed whole organisms or toxoids still predominate the market for livestock, with the major improvements being in regulatory control over vaccine safety and efficacy. These traditional vaccines generally confer excellent levels of immunity as they present a range of antigens to the immune system in the natural context of the whole organism. Although there has been significant progress in the development of recombinant and subunit vaccine antigens, very few of these have found their way on to the market as they generally do not induce good immunity without the use of strong adjuvants. Currently, chemical treatments such as drench and dips remain the most commonly used means of parasite control in livestock. The use of such chemicals is problematic, however, due to the development of parasite resistance against many anthelmintics (Waller, 1997) and the inherent safety problems of chemical use to both livestock and operator. The provision of immune protection against parasites would, therefore, be beneficial. There are a number of impediments to effective anti-parasite control by vaccina-
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
241
tion including the fact that many parasites have a life cycle in more than one host species, allowing wild animal species to remain a reservoir of infection. In addition, parasites generally express stage-specific antigens, complicating development of suitable vaccine target antigens. Despite this, there has been some success in the production of anti-parasite vaccines. A recombinant vaccine against Taenia o6is (Johnson et al., 1989) has been registered for use in New Zealand (Rickard et al., 1995) and irradiated larval vaccines against lungworm in cattle, sheep and goats (Dictyocaulus spp.) have become commercially available (Bain, 1999). There has also been progress towards the development of vaccines for ectoparasite control, with two cattle tick vaccines being marketed (Fragoso et al., 1998; Jonsson et al., 2000). A number of challenges remain in the development of vaccines for disease or parasite control. While traditional vaccines have been shown to confer excellent humoral immunity, the selective induction of cellular immunity required for protection against many organisms remains problematic given that the range of adjuvants that can be safely used in livestock is limited. Similarly, the induction of mucosal responses that would provide early prevention against many organisms at their portal of entry also remains difficult using conventional peripheral routes of delivery. A further challenge in vaccine development is the provision of protective immunity after a single administration of antigen. There are two concepts that are particularly relevant in the success of vaccination against disease or parasites. First, it is important to note that the use of vaccines in outbred populations will always result in considerable variability in the level and type of immune response generated against any vaccine. As vaccine technology moves towards the use of more defined antigens in vaccines, this variability can be expected to increase. The concept of herd immunity is, therefore, an important one, as this allows complete interruption of disease transmission within a population even in cases where a vaccine is not 100% efficacious. Second, effective vaccination against disease aims to induce immune memory so that rapid induction of response is generated following exposure to the wild-type organism in the field. While existing effector responses are of benefit in early protection, it is the memory response that is generally relied upon for continued protection.
3. Vaccination against reproductive hormones In recent years there has been significant progress in the development of anti-fertility vaccines. Target antigens have included sperm and zona pellu-
242
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
cida antigens (Bradley et al., 1999) as well as reproductive hormones (Baird, 2000). While the use of these vaccines in humans and wild animals has been limited strictly to control of reproduction, vaccination against the reproductive hormones has a multitude of uses in livestock, including the control of growth and metabolism, the improvement of carcass quality and modification of behaviour. All of these factors are of significance in the optimisation of animal production. Gonadotropin releasing hormone (GnRH), or luteinizing hormone releasing hormone (LHRH) is the most widely used target in fertility control vaccines in livestock (Thompson, 2000). It is significantly different from traditional types of vaccine antigens in that it is a self-antigen and is too small to be immunogenic. To induce an immune response against GnRH or its analogues, there must be a linkage to a carrier protein and molecules such as bovine serum albumin (BSA) (Fraser and Gunn, 1973), polvinylpyrrolidone (Arimura et al., 1973) or tetanus toxoid (Sad et al., 1991) have been employed as carriers in various experimental systems. When used for vaccination in bull calves and appropriate antibody titres have been achieved, the results have included reduced testes size and testosterone levels, associated with reduced aggressive behaviour (Jago et al., 1999). In addition, up to 32% reduced fat levels, 50% more rib eye area at the 10th rib and a 12% decrease in feed:gain ratio in comparison to steers have resulted from anti-GnRH vaccination (Robertson et al., 1982), making immunocastration a preferable option in place of surgical castration. Vaxstrate™ was an anti-GnRH vaccine based on a carboxyl-containing GnRH analog conjugated to ovalbumin that was commercially available in Northern Australia in the early 1990s. The product was used as a contraceptive vaccine in heifers run in extensive management systems (Hoskinson et al., 1990). The prevention of pregnancy ensured maximum resources were allocated to weight gain in cattle marked for slaughter. More recently, a GnRH conjugate vaccine has been marketed by CSL Ltd, Australia (Improvac™) for prevention of boar taint in pigs (Dunshea et al., 2000). Boar taint is the offensive odour detected by up to 75% of consumers in the meat of male pigs. It is caused by deposition of androstenone and skatole in the fat and it is estimated that up to 20% of male pigs are highly tainted at slaughter weight ( 90 kg) and a further 20– 30% are moderately tainted (Bonneau et al., 1992). The product is aimed at improving carcass quality without the need for castration of boars, which is associated with a stress-induced reduced feed efficiency. It has also been shown to increase growth performance and decrease aggressive behaviour in vaccinated animals (McCauley et al., 2000). In wild animal species, where population control is the primary aim, reduced reproductive performance in the population will adversely affect the
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
243
population numbers. In this sense, the concept of herd immunity applies. In the case of livestock production, however, the aim is to improve performance in each individual and herd immunity is not relevant in improving the performance of the stock. It is important that each individual responds well to the vaccine. In addition, there is little dependence on the induction of immune memory. Animals vaccinated with conjugate vaccine will not respond to a challenge of naturally occurring hormone secretion, but require a second dose of vaccine. There is a need to consistently maintain antibody titres following vaccination that will neutralise any natural secretions of hormone. This high circulating antibody level is particularly important when the vaccines are used for contraception. The successful use of these vaccines is, therefore, dependent on complete coverage, high efficacy and long duration of response. Land et al. (1982) dealt with the problem of variability and delay in induction of immune responses by passive treatment of ewes at mating with antisera raised against gonadal steroids including oestrone, oestrodiol, androstenedione and testosterone. These treatments were effective in increasing ovulation rates, resulting in an increase in the number of lambs born per ewe. In the absence of large scale production of such antisera, however, immunological approaches to enhancing production will be dependent on the ability to effectively and reproducibly enhance the immune response to vaccination with target antigens.
4. Limitations for immune intervention in livestock Management systems for livestock production may impose limitations on the use of certain delivery methods or immunisation protocols. Under extensive management systems such as on cattle farms in Northern Australia, stock are typically mustered only once per year, limiting access to repeated vaccination and often resulting in suboptimal protection. However, even where stock access is not problematic such as in feedlot systems, it is preferable to minimise animal handling to reduce stress that may adversely affect weight gain in livestock. Minimal stock handling is also more cost-effective and reduces the chance of injury to the operator. This highlights the need for vaccines that induce complete immunity after only a single administration. As most meat and milk products from livestock are destined for human consumption, there are stringent safety requirements imposed on animal health products. As some harsh adjuvants such as some mineral oils may leave chemical residues, their use is limited to the subcutaneous route and appropriate levels of safety must be demonstrated. Adverse site reactions
244
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
also reduce carcass or hide quality with a subsequent reduction in product sale value. The choice of adjuvants and vaccine delivery route and site are, therefore, important considerations. Finally, commercial considerations limit the usage of vaccines in livestock production (summarised in Schetters, 1995). Vaccines for livestock must be cost-effective and not exceed the gains that can be made through increased production or enhanced meat quality for example, which would attract higher market prices. An important consideration in the market is also the willingness of consumers to purchase food products derived through biotechnological intervention. While the existing programme of vaccination in meat animals has consumer acceptability, the extension of these principles to the manipulation of biological activities such as reproduction may need to be preceded by consumer education programmes and new approaches to marketing.
5. Optimising vaccine delivery To maximise the utility of vaccination in livestock industries, there is a requirement for further development of methods aimed at increasing the level of immune response elicited, as well as methods of manipulating the response towards the most appropriate immune mechanism for any particular disease. Specifically, better methods of inducing both cellular and mucosal responses are required that must fit within the practical limitations of livestock management practices. In addition, a primary goal of vaccine research has been the provision of protective immunity with extended duration of response after only a single dose of vaccine. This goal is now most important for the effective application of anti-fertility vaccines. While a large body of vaccine research aims to find suitable target antigens, the use of these antigens must be combined with appropriate methods of vaccine delivery to ensure optimal efficacy. Vaccine development studies routinely optimise antigen dose, route and timing of delivery as well as use of adjuvants. Aluminium hydroxide remains the most widely used vaccine adjuvant in livestock species. It is used universally for combined clostridial vaccines in sheep and cattle and a range of other killed vaccines against viral and bacterial antigens. This adjuvant is primarily an inducer of antibody of the IgG1 class and has limited efficacy for inducing cellular immunity (Cox and Coulter, 1997). It does, however, have an excellent safety record and induces minimal site reactions except for the occasional occurrence of sterile abscesses at the injection site (Gupta et al., 1993). For vaccines that require strong antibody responses or cellular immunity, mineral oil emulsion adju-
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
245
vants are often used commercially in livestock provided that they fulfil defined safety requirements. Although granulomas at the injection site may also occur subsequent to administration of a mineral oil based vaccine, there is evidence that this results in enhanced immunity by providing an antigen depot (Lascelles et al., 1989). Quil A, a purified derivative of saponin, has also been used as a commercial adjuvant in some vaccines. In addition, Immunostimulating Complexes (ISCOMS) have been widely applied to experimental veterinary vaccines and their use has been reviewed elsewhere (Bowersock and Martin 1999).
6. Controlled antigen release —potential for single dose vaccination In recent years, developments in drug delivery for the pharmaceutical industry have provided methods for controlled release of antigen over long periods. These new methods of manipulating antigen delivery have potential to allow single-dose vaccination and may prove to be of particular benefit for anti-fertility vaccines that require extended duration of antibody response. Early studies in immunology have suggested that pulsatile antigen delivery was required for induction of immunity while continuous antigen delivery resulted in immune tolerance. Analysis of these studies have shown that repeated multiple injections were used, as no suitable method of long term antigen delivery was available, and that poor antigens were often used, in the absence of adjuvant. There are now sufficient data available to demonstrate that immunity can indeed be induced by continuous antigen release when delivered appropriately, using vehicles that preserve the integrity of the antigen. These methods are summarised in Table 1. The influence of varying antigen release profiles on the size and type of the ensuing immune response, however, is yet to be understood. Microspheres have been most widely tested as vaccine delivery vehicles, with polymers, particularly polylactide-co-glycolide (PLGA) being most commonly used for their production. Microspheres offer the advantage of being injectable, and the release rate of antigen may be modified either by varying the particle size or the ratio of polymers used in their production (lactic acid:glycolic acid). In addition, microspheres may be applied via the oral or nasal route for induction of mucosal immune responses (McDermott et al., 1998). While a pulsatile release profile may be theoretically elicited by use of two different size or density microspheres, there is effectively two populations of particles whose release profiles are likely to overlap, resulting in varied but continuous antigen release. Problems associated with use of some polymer microspheres include the use of extremes of temperature or
In vitro
Mice, Sheep
Mice
Newcastle disease vaccine
Ovalbumin
Human gamma globulin
Bovine serum albumin
Avidin/IL-1b Bovine serum albumin
Recombinant Dichelobacter nodosus antigen/Quil A
Avidin, C. tetanus and C.no6yi toxoids/rovIL-1b
BSA, g-globulin, ribonuclease
Alginate microsphere
Gelatin Microsphere
Osmotic pump
Silicone implant Cholesterol implant
Cholesterol/lecithin implant
Collagen minipellet
Ethylene-vinyl acetate co-polymer implant
Sheep
Mice Mice
Mice
Mice
Cattle
Mice
Human serum albumin
Mice
Ovalbumin
Polymer grafted starch microsphere Chitosan microsphere
Guinea pigs
Tetanus toxoid/rehydragel
PLGA microsphere
Species
Antigen/adjuvant
Delivery method
Table 1 Delivery systems for controlled antigen release
High neutralising antibody titres High antibody titres maintained for \1 year IgG responses compared with soluble Chemical modification provided range of release rates in vitro Mucosal responses recorded at lung; optimal responses from subcutaneous priming and oral booster IgG and DTH responses induced Equivalent antibody response to multiple injections High antibody titres Antibody response exceeded that induced by three doses Antibody response equivalent to two doses administered in Quil A Implant vaccination induced antibody responses exceeding alum-adjuvanted vaccination in mice, and equivalent to alum-adjuvanted vaccination in sheep Elevated antibody titres for 6 months, IgG
Results
Preis and Langer, 1979
Lofthouse et al., 2001
Kajihara et al., 1999 Opdebeeck and Tucker, 1993 Walduck et al., 1998
Walduck and Opdebeeck, 1997
Nakaoka et al., 1995
Bowersock et al., 1998
Heritage et al., 1996; McDermott et al., 1998 Mi et al., 1999
Coombes et al., 1996
Johansen et al., 1998
Reference
246 S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
247
pH, and organic solvents during production, as well as the in vivo breakdown into acidic by-products that may adversely affect antigen stability. In addition, polymers are often too expensive to be used for routine livestock vaccination. Modified production methods (Audran et al., 1998; Johansen et al., 1998; Tracy, 1998) and use of alternative materials including alginate (Bowersock et al., 1998, 1999), starch (Heritage et al., 1996; McDermott et al., 1998), gelatin (Nakaoka et al., 1995) and chitosan (Mi et al., 1999) are currently being investigated to overcome these problems. An alternative delivery method is the use of injectable implants impregnated with antigen and/or adjuvant. This method was first demonstrated in 1979 by Preis and Langer (Preis and Langer, 1979) who used ethylene vinyl acetate co-polymer to induce antibody titres in mice that exceeded those induced by two injections of antigen in Freund’s complete adjuvant for over 6 months. A range of alternative implant excipients including cholesterol (Opdebeeck and Tucker, 1993), cholesterol/lecithin (Walduck et al., 1998), collagen (Lofthouse et al., 2001; Fujioka et al., 1995a) and silicone (Kajihara et al., 2000) have since been examined. In our laboratory we have investigated both degradable collagen implants and non-degradable silicone implants as vaccine delivery vehicles. These implants were developed by Sumitomo Pharmaceutical Co. Ltd., Japan, for the delivery of protein pharmaceuticals, particularly cytokines (Fujiwara et al., 1990; Fujioka et al., 1995b). Our studies were conducted in both mice (Kajihara et al., 1999) and sheep (Kemp et al., 2002), using the model antigen avidin and Clostridium tetanus and C. no6yi toxoids combined with recombinant ovine interleukin-1b (rovIL-1b), a cytokine whose adjuvant properties has been previously demonstrated in sheep (Andrews et al., 1994). A range of implants was tested that released antigen over a range of time periods with different delivery profiles. Although all implants tested were shown to be able to induce antibody responses equivalent to that induced by conventional vaccination (two injections of antigen in alum adjuvant; Lofthouse et al., 2001), the ‘silicone covered rod’ implant showed most potential for use as a single-dose vaccine delivery vehicle. RovIL-1b was used as an adjuvant due to the need for provision of implant raw materials that could be freeze (or spray) dried. In addition, the small size of the implant (2 mm diameter×10 mm length) was ideal for delivery of cytokine adjuvants that are active at very low doses. When avidin was released from the silicone covered rods with rovIL-1b adjuvant, a single administration maintained antibody titres at a level significantly exceeding that induced by two equivalent doses of avidin injected with alum adjuvant. In addition, the antibody induced was of high affinity and comprised both sheep IgG isotypes, IgG1 and IgG2, with the IgG2 response induced being two-fold higher than that induced by conventional vaccina-
248
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
tion. After antigenic challenge of vaccinated sheep, an improved memory response was also evident in sheep vaccinated with the single covered rod compared with conventionally vaccinated controls. These data are summarised in Figs. 1–3 and further described in Kemp et al. (2002). The responses elicited by the covered rod implant were entirely dependent on the inclusion of adjuvant into the implant formulation. Implants that delivered antigen only induced antibody responses equivalent to those induced by antigen delivered in saline alone, indicating that slow release of antigen was in itself not capable of enhancing the immune response. Immune responses elicited were primarily antibody mediated, making the implants an ideal vehicle for delivery of clostridial toxoids. Vaccination studies in sheep using C. tetanus and C. no6yi toxoids confirmed the superiority of the covered rod implant over conventional alum-adjuvanted vaccination, with neutralising titres induced by the covered rod implants being up to three-fold higher than for the conventionally vaccinated control animals (Lofthouse, unpublished results). Further studies are being conducted using different adjuvants to attempt to modulate the type of response elicited by implant vaccination.
Fig. 1. Avidin-specific antibody responses elicited in sheep by vaccination with either a single administration (subcutaneous) at day 0, of a silicone covered rod adjuvanted with rovIL-1b ( ), or two doses of avidin in alum adjuvant delivered at days 0 and 28 by subcutaneous injection ( ). The arrow indicates the time of secondary administration of antigen to the injected group. Group serum pools were titrated at each time point to determine the 50% response titre (n=7).
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
249
Fig. 2. Avidity of avidin-specific antibody elicited in sheep 14 days after a single vaccination with avidin and rovIL-1b in implants, or avidin in alum injected subcutaneously. The covered rod implant delivers antigen in vitro in a zero order (constant daily rate) profile for several months. The matrix implant delivers antigen in vitro in a first order (reducing rate) for 1 month. The inverse avidity index was determined by binding inhibition ELISA; higher inverse avidity index indicates higher avidity. Group serum pools were used (n =7).
While there are significant opportunities to improve animal production by manipulating the immune response for a variety of biological systems, the specific developments in this area must be met by improvements in basic vaccine technologies that will allow these new approaches to be most effective under field conditions. The importance of vaccine delivery cannot be underestimated. Although experimental systems have demonstrated the potential for induction of cellular and mucosal responses, and the ability to improve and extend the immune response elicited, further studies are required to develop these methods into practical vaccine delivery strategies that will complement existing animal management practices and fulfil safety requirements. The recent advent of controlled release methods such as those described above, and other novel techniques of antigen delivery such as DNA vaccination (reviewed in Watts and Kennedy, 1999) offers potential for the production of single dose vaccines which will greatly enhance the use of these products in livestock industries.
250
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
Fig. 3. Isotype-specific anti-avidin antibody responses elicited in sheep 69 days after either a single administration of the covered rod implant adjuvanted with rovIL-1b, or two injections of avidin in alum injected subcutaneously. Both sheep IgG isotypes are shown; IgG1 (solid bars) and IgG2 (hashed bars). Group serum pools were used in an ELISA assay.
References Andrews, A., Lofthouse, S., Bowles, V.M., Brandon, M.R., Nash, A.D., 1994. Production and in vivo use of recombinant ovine IL-1b as an immunological adjuvant. Vaccine 12, 14 –22. Arimura, A., Sato, H., Kumasaka, T., Worobec, R.B., Debeljuk, L., Dunn, J., Schally, A.V., 1973. Production of antiserum to LH-releasing hormone (LH-RH) associated with gonadal atrophy in rabbits: development of radioimmunoassays for LH-RH. Endocrinology 93, 1092 –1103. Audran, R., Men, Y., Johansen, P., Gander, B., Corradin, G., 1998. Enhanced immunogenicity of microencapsulated tetanus toxoid with stabilizing agents. Pharm. Res. 15, 1111 –1116. Bain, R., 1999. Irradiated vaccines for helminth control in livestock. Int. J. Parasitol. 29, 185 –191. Baird, D., 2000. Overview of advances in contraception. Br. Med. Bull. 56, 704 –716. Bonneau, M., Denmat, M.L., Vaudelet, J.C., Veloso Nunes, J.R., Mortensen, A.B., Mortensen, H.P., 1992. Contributions of fat androstenone and skatole to boar taint: I. Sensory attributes of fat and pork meat. Livestock Prod. Sci. 32, 63 –80.
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
251
Bowersock, T.L., Martin, S., 1999. Vaccine delivery to animals. Adv. Drug Delivery Rev. 38, 167 –194. Bowersock, T.L., HogenEsch, H., Torregrosa, S., Borie, D., Wang, B., Park, H., Park, K., 1998. Induction of pulmonary immunity in cattle by oral administration of ovalbumin in alginate microspheres. Immunol. Lett. 60, 37 – 43. Bowersock, T.L., HogenEsch, H., Suckow, M., Guimond, P., Martin, S., Borie, D., Torregrosa, S., Park, H., Park, K., 1999. Oral vaccination of animals with antigens encapsulated in alginate microspheres. Vaccine 17, 1804 –1811. Bradley, M., Eade, J., Penhale, J., Bird, P., 1999. Vaccines for fertility regulation of wild and domestic species. J. Biotechnol. 73, 91 – 101. Coombes, A.G., Lavelle, E.C., Jenkins, P.G., Davis, S.S., 1996. Single dose, polymeric, microparticle-based vaccines: the influence of formulation conditions on the magnitude and duration of the immune response to a protein antigen. Vaccine 14, 1429 –1438. Cox, J.C., Coulter, A.R., 1997. Adjuvants-a classification and review of their modes of action. Vaccine 15, 248 –256. Dunshea, F., Colantoni, C., Howard, K., Jackson, P., Long, K.A., Lopaticki, S., Nugent, E.A., Simons, J.A., Walker, J., Hennessy, D.P., 2000. Vaccination of entire boars with Improvac eliminates boar taint and increases growth performance. J. Animal Sci. 83, 138. Fragoso, H., Rad, P.H., Ortiz, M., Rodriguez, M., Redondo, M., Herrera, L., de la Fuente, J., 1998. Protection against Boophilus annulatus infestations in cattle vaccinated with the B. microplus Bm86-containing vaccine Gavac. Vaccine 16, 1990 –1992. Fraser, H., Gunn, H., 1973. Effects of antibodies to luteinizing hormone-releasing hormone in the male rabbit and on the rat oestrus cycle. Nature 244, 160 – 161. Fujioka, K., Takada, Y., Sato, S., Miyata, T., 1995a. Long-acting delivery system of interferon: IFN minipellet. J. Control Release 33, 317 – 323. Fujioka, K., Takada, Y., Sato, S., Miyata, T., 1995b. Novel delivery system for proteins using collagen as a carrier material: the minipellet. J. Control. Release 33, 307 –315. Fujiwara, T., Sakagami, K., Orita, K., 1990. Antitumour effects of a new interleukin-2 slow delivery system on methylcholanthrene-induced fibrosarcoma in mice. J. Cancer Res. Clin. Oncol. 116, 141 –148. Gupta, R.K., Relyveld, E.H., Lindblad, E.B., Bizzini, B., Ben-Efraim, S., Gupta, C.K., 1993. Adjuvants-a balance between toxicity and adjuvanticity. Vaccine 11, 293 – 306. Heritage, P.L., Loomes, L.M., Jianxiong, J., Brook, M.A., Underdown, B.J., McDermott, M.R., 1996. Novel polymer-grafted starch microparticles for mucosal delivery of vaccines. Immunology 88, 162 –168. Hoskinson, R., Rigby, R., Mattner, P.E., Huynh, V.L., D’Occhio, M., Neish, A., Trigg, T.E., Moss, B.A., Lindsay, M.J., Coleman, G.D., Schwartzkoff, C.L., 1990. Vaxstrate: an anti-reproductive vaccine for cattle. Aust. J. Biotechnol. 4, 166 –170. Jago, J., Matthews, L., Trigg, T.E., Dobbie, P., Bass, J.J., 1999. The effect of immunocastration 7 weeks before slaughter on the behaviour, growth and meat quality of post-pubertal bulls. Animal Sci. 68, 163 –171. Johansen, P., Men, Y., Audran, R., Corradin, G., Merkle, H.P., Gander, B., 1998. Improving stability and release kinetics of microencapsulated tetanus toxoid by co-encapsulation of additives. Pharm. Res. 15, 1103 –1110. Johnson, K.S., Harrison, G.B., Lightowlers, M.W., O’Hoy, K.L., Cougle, W.G., Dempster, R.P., Lawrence, S.B., Vinton, J.G., Heath, D.D., Rickard, M.D., 1989. Vaccination against ovine cysticercosis using a defined recombinant antigen. Nature 338, 585 – 587. Jonsson, N.N., Matschoss, A.L., Pepper, P., Green, P.E., Albrecht, M.S., Hungerford, J., Ansell, J., 2000. Evaluation of tickGARD(PLUS), a novel vaccine against Boophilus microplus, in lactating Holstein –Friesian cows. Vet. Parasitol. 88, 275 –285.
252
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
Kajihara, M., Sugie, T., Nagahara, S., Hanai, K., Sano, A., Lofthouse, S., Nash, A., Brandon, M., 1999. Controlled release system as novel vaccination method. Proc. Int. Symp. Control Rel. Bioact. Mater. 26, 1042 – 1043. Kajihara, M., Sugie, T., Mizuno, M., Tamura, T., Sano, A., Fujioka, K., Kashiwazaki, Y., Yamaoka, T., Sugawara, S., Urabe, Y., 2000. Development of a new drug delivery system for protein drugs using silicone (I). J. Control Release 66, 49 –61. Kemp, J.M., Kajihara, M., Nagahara, S., Sano, A., Brandon, M., Lofthouse, S., 2002. Continuous antigen delivery from controlled release implants induces significant and anamnestic immune responses. Vaccine. 20, 1089 – 1098. Land, R.B., Morris, B.A., Baxter, G., Fordyce, M., Forster, J., 1982. Improvement of sheep fecundity by treatment with antisera to gonadal steroids. J. Reprod. Fertil. 66, 625 – 634. Lascelles, A.K., Eagleson, G., Beh, K.J., Watson, D.L., 1989. Significance of Freund’s adjuvant/antigen injection granuloma in the maintenance of serum antibody response. Vet. Immunol. Immunopathol. 22, 15 – 27. Lofthouse, S., Nagahara, S., Sedgmen, B., Barcham, G., Brandon, M., Sano, A., 2001. The application of biodegradable collagen minipellets as vaccine delivery vehicles in mice and sheep. Vaccine 19, 4318 –4327. McCauley, I., Cronin, G., Barnett, J.L., Butler, K.L., Hennessy, D.P., Campbell, R.G., Luxford, B., Smits, R.J., Tillbrook, A.J., Dunshea, F.R., 2000. An immunocastration vaccine (Improvac) increases growth in individually and group-housed boars. J. Animal Sci. 83, 138. McDermott, M.R., Heritage, P.L., Bartzoka, V., Brook, M.A., 1998. Polymer-grafted starch microparticles for oral and nasal immunisation. Immunol. Cell Biol. 76, 256 –262. Mi, F.L., Shyu, S.S., Chen, C.T., Schoung, J.Y., 1999. Porous chitosan microsphere for controlling the antigen release of Newcastle disease vaccine: preparation of antigen-adsorbed microsphere and in vitro release. Biomaterials 20, 1603 –1612. Nakaoka, R., Tabata, Y., Ikada, Y., 1995. Potentiality of gelatin microsphere as immunological adjuvant. Vaccine 13, 653 –661. Opdebeeck, J., Tucker, I., 1993. A cholesterol implant used as a delivery system to immunise mice with bovine serum albumin. J. Control Release 23, 271 –279. Pasteur, L., 1880. De l’attenuation du virus du cholera des poules. CR Acad. Sci. Paris 91, 673–680. Pasteur, L., Chamberland, C., Roux, R., 1881. Sur la vaccination charboneusse. CR Acad. Sci. Paris 92, 1378 –1383. Preis, I., Langer, R., 1979. A single-step immunisation by sustained antigen release. J. Immunol. Methods 28, 193 –197. Rickard, M.D., Harrison, G.B., Heath, D.D., Lightowlers, M.W., 1995. Taenia o6is recombinant vaccine —‘quo vadit’. Parasitology 110, S5 –S9. Robertson, I., Fraser, H., Innes, G.M., Jones, A.S., 1982. Effect of immunological castration on sexual and production characteristics in male cattle. Vet. Rec. 116, 74 –75. Sad, S., Gupta, H., Talwar, G.P., Raghupathy, R., 1991. Carrier-induced suppression of the antibody response to a ‘self’ hapten. Immunology 74, 223 – 227. Schetters, T., 1995. Vaccine development from a commercial point of view. Vet. Parasitol. 57, 267 –275. Thompson, D., 2000. Immunisation against GnRH in male species. Animal Reprod. Sci. 60–61, 459 –469. Tracy, M.A., 1998. Development and scale-up of a microsphere protein delivery system. Biotechnol. Prog. 14, 108 –115.
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
253
Walduck, A., Opdebeeck, J.P., 1997. Effect of profile of antigen delivery on antibody responses in mice. J. Control. Release 43, 75 – 80. Walduck, A., Opdebeeck, J., Benson, H.E., Prankerd, R., 1998. Biodegradable implants for the delivery of veterinary vaccines: design, manufacture and antibody responses in sheep. J. Control. Release 51, 269 –280. Waller, P., 1997. Anthelmintic resistance. Vet. Parasitol. 72, 391 –412. Watts, A.M., Kennedy, R.C., 1999. DNA vaccination strategies against infectious diseases. Int. J. Parasitol. 29, 1149 –1163.
Manipulating the immune response; applications in livestock breeding Shari Lofthouse *, Joanna Kemp Centre for Animal Biotechnology, School of Veterinary Science, The Uni6ersity of Melbourne, 3010, Vic., Australia
Abstract There are many opportunities for the use of immune modulation techniques in livestock that offer the potential to reduce the requirements for chemical usage and surgical intervention in standard management practices. While vaccination has been used for many years for disease control, there are areas in which vaccination has not been very successful, including the induction of mucosal responses, the induction of cellular responses, and the ability to induce extended duration of protection after a single administration of antigen. In addition, new areas of immunological intervention such as immunisation against reproductive hormones offer new opportunities to modify not only reproductive performance, but also growth, metabolism, carcass quality and behaviour in livestock. These new techniques bring increased need for enhanced efficacy and duration of response. While extensive studies in vaccination have shown that many of the desired immunological responses can be induced in experimental conditions, effective application in the field is dependent upon the development of vaccine delivery methods that are practical within the confines of an effective livestock management system. This paper outlines restrictions that may be imposed on vaccine delivery to livestock and introduces controlled antigen delivery as a potential method for single dose vaccination. © 2002 Published by Elsevier Science Ireland Ltd. Keywords: Immune modulation; Controlled release; Vaccine deliver; Vaccination
* Corresponding author. Fax: + 61-3-9347-4083. E-mail address: [email protected] (S. Lofthouse). 0165-0378/02/$ - see front matter © 2002 Published by Elsevier Science Ireland Ltd. PII: S 0 1 6 5 - 0 3 7 8 ( 0 2 ) 0 0 0 0 6 - 2
240
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
1. Introduction Traditional approaches in livestock production have employed procedures such as surgical intervention and chemical treatment for control of pests, diseases and fertility. These methods often induce undue stresses on stock and result in chemical residues adversely affecting meat, milk or wool quality. Immune intervention offers excellent potential for manipulation of livestock production with minimal invasive treatments, resulting in reduced stress, reduced labour costs and increased animal production. Recent advances in immunology have extended the capacities of vaccination beyond the classical use for disease control, and it is now possible to intervene in many physiological functions. Although there are potential benefits arising from use of these technologies, their successful application in industry is dependent on methods of vaccination that provide responses of sufficient magnitude and duration and resulting in the appropriate immune phenotype. Careful selection of vaccine delivery method, the use of appropriate adjuvants and the application of novel methods of controlled antigen delivery are currently being used to meet these aims.
2. Vaccination for pathogen and parasite control Vaccination remains the most cost-effective method of disease control. Its use in livestock was first demonstrated by Louis Pasteur in the late 1800s using a Pasteurella multocida vaccine for fowl cholera (Pasteur, 1880) and an anthrax vaccine for sheep (Pasteur et al., 1881). Despite over 100 years of vaccine development, attenuated and/or killed whole organisms or toxoids still predominate the market for livestock, with the major improvements being in regulatory control over vaccine safety and efficacy. These traditional vaccines generally confer excellent levels of immunity as they present a range of antigens to the immune system in the natural context of the whole organism. Although there has been significant progress in the development of recombinant and subunit vaccine antigens, very few of these have found their way on to the market as they generally do not induce good immunity without the use of strong adjuvants. Currently, chemical treatments such as drench and dips remain the most commonly used means of parasite control in livestock. The use of such chemicals is problematic, however, due to the development of parasite resistance against many anthelmintics (Waller, 1997) and the inherent safety problems of chemical use to both livestock and operator. The provision of immune protection against parasites would, therefore, be beneficial. There are a number of impediments to effective anti-parasite control by vaccina-
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
241
tion including the fact that many parasites have a life cycle in more than one host species, allowing wild animal species to remain a reservoir of infection. In addition, parasites generally express stage-specific antigens, complicating development of suitable vaccine target antigens. Despite this, there has been some success in the production of anti-parasite vaccines. A recombinant vaccine against Taenia o6is (Johnson et al., 1989) has been registered for use in New Zealand (Rickard et al., 1995) and irradiated larval vaccines against lungworm in cattle, sheep and goats (Dictyocaulus spp.) have become commercially available (Bain, 1999). There has also been progress towards the development of vaccines for ectoparasite control, with two cattle tick vaccines being marketed (Fragoso et al., 1998; Jonsson et al., 2000). A number of challenges remain in the development of vaccines for disease or parasite control. While traditional vaccines have been shown to confer excellent humoral immunity, the selective induction of cellular immunity required for protection against many organisms remains problematic given that the range of adjuvants that can be safely used in livestock is limited. Similarly, the induction of mucosal responses that would provide early prevention against many organisms at their portal of entry also remains difficult using conventional peripheral routes of delivery. A further challenge in vaccine development is the provision of protective immunity after a single administration of antigen. There are two concepts that are particularly relevant in the success of vaccination against disease or parasites. First, it is important to note that the use of vaccines in outbred populations will always result in considerable variability in the level and type of immune response generated against any vaccine. As vaccine technology moves towards the use of more defined antigens in vaccines, this variability can be expected to increase. The concept of herd immunity is, therefore, an important one, as this allows complete interruption of disease transmission within a population even in cases where a vaccine is not 100% efficacious. Second, effective vaccination against disease aims to induce immune memory so that rapid induction of response is generated following exposure to the wild-type organism in the field. While existing effector responses are of benefit in early protection, it is the memory response that is generally relied upon for continued protection.
3. Vaccination against reproductive hormones In recent years there has been significant progress in the development of anti-fertility vaccines. Target antigens have included sperm and zona pellu-
242
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
cida antigens (Bradley et al., 1999) as well as reproductive hormones (Baird, 2000). While the use of these vaccines in humans and wild animals has been limited strictly to control of reproduction, vaccination against the reproductive hormones has a multitude of uses in livestock, including the control of growth and metabolism, the improvement of carcass quality and modification of behaviour. All of these factors are of significance in the optimisation of animal production. Gonadotropin releasing hormone (GnRH), or luteinizing hormone releasing hormone (LHRH) is the most widely used target in fertility control vaccines in livestock (Thompson, 2000). It is significantly different from traditional types of vaccine antigens in that it is a self-antigen and is too small to be immunogenic. To induce an immune response against GnRH or its analogues, there must be a linkage to a carrier protein and molecules such as bovine serum albumin (BSA) (Fraser and Gunn, 1973), polvinylpyrrolidone (Arimura et al., 1973) or tetanus toxoid (Sad et al., 1991) have been employed as carriers in various experimental systems. When used for vaccination in bull calves and appropriate antibody titres have been achieved, the results have included reduced testes size and testosterone levels, associated with reduced aggressive behaviour (Jago et al., 1999). In addition, up to 32% reduced fat levels, 50% more rib eye area at the 10th rib and a 12% decrease in feed:gain ratio in comparison to steers have resulted from anti-GnRH vaccination (Robertson et al., 1982), making immunocastration a preferable option in place of surgical castration. Vaxstrate™ was an anti-GnRH vaccine based on a carboxyl-containing GnRH analog conjugated to ovalbumin that was commercially available in Northern Australia in the early 1990s. The product was used as a contraceptive vaccine in heifers run in extensive management systems (Hoskinson et al., 1990). The prevention of pregnancy ensured maximum resources were allocated to weight gain in cattle marked for slaughter. More recently, a GnRH conjugate vaccine has been marketed by CSL Ltd, Australia (Improvac™) for prevention of boar taint in pigs (Dunshea et al., 2000). Boar taint is the offensive odour detected by up to 75% of consumers in the meat of male pigs. It is caused by deposition of androstenone and skatole in the fat and it is estimated that up to 20% of male pigs are highly tainted at slaughter weight ( 90 kg) and a further 20– 30% are moderately tainted (Bonneau et al., 1992). The product is aimed at improving carcass quality without the need for castration of boars, which is associated with a stress-induced reduced feed efficiency. It has also been shown to increase growth performance and decrease aggressive behaviour in vaccinated animals (McCauley et al., 2000). In wild animal species, where population control is the primary aim, reduced reproductive performance in the population will adversely affect the
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
243
population numbers. In this sense, the concept of herd immunity applies. In the case of livestock production, however, the aim is to improve performance in each individual and herd immunity is not relevant in improving the performance of the stock. It is important that each individual responds well to the vaccine. In addition, there is little dependence on the induction of immune memory. Animals vaccinated with conjugate vaccine will not respond to a challenge of naturally occurring hormone secretion, but require a second dose of vaccine. There is a need to consistently maintain antibody titres following vaccination that will neutralise any natural secretions of hormone. This high circulating antibody level is particularly important when the vaccines are used for contraception. The successful use of these vaccines is, therefore, dependent on complete coverage, high efficacy and long duration of response. Land et al. (1982) dealt with the problem of variability and delay in induction of immune responses by passive treatment of ewes at mating with antisera raised against gonadal steroids including oestrone, oestrodiol, androstenedione and testosterone. These treatments were effective in increasing ovulation rates, resulting in an increase in the number of lambs born per ewe. In the absence of large scale production of such antisera, however, immunological approaches to enhancing production will be dependent on the ability to effectively and reproducibly enhance the immune response to vaccination with target antigens.
4. Limitations for immune intervention in livestock Management systems for livestock production may impose limitations on the use of certain delivery methods or immunisation protocols. Under extensive management systems such as on cattle farms in Northern Australia, stock are typically mustered only once per year, limiting access to repeated vaccination and often resulting in suboptimal protection. However, even where stock access is not problematic such as in feedlot systems, it is preferable to minimise animal handling to reduce stress that may adversely affect weight gain in livestock. Minimal stock handling is also more cost-effective and reduces the chance of injury to the operator. This highlights the need for vaccines that induce complete immunity after only a single administration. As most meat and milk products from livestock are destined for human consumption, there are stringent safety requirements imposed on animal health products. As some harsh adjuvants such as some mineral oils may leave chemical residues, their use is limited to the subcutaneous route and appropriate levels of safety must be demonstrated. Adverse site reactions
244
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
also reduce carcass or hide quality with a subsequent reduction in product sale value. The choice of adjuvants and vaccine delivery route and site are, therefore, important considerations. Finally, commercial considerations limit the usage of vaccines in livestock production (summarised in Schetters, 1995). Vaccines for livestock must be cost-effective and not exceed the gains that can be made through increased production or enhanced meat quality for example, which would attract higher market prices. An important consideration in the market is also the willingness of consumers to purchase food products derived through biotechnological intervention. While the existing programme of vaccination in meat animals has consumer acceptability, the extension of these principles to the manipulation of biological activities such as reproduction may need to be preceded by consumer education programmes and new approaches to marketing.
5. Optimising vaccine delivery To maximise the utility of vaccination in livestock industries, there is a requirement for further development of methods aimed at increasing the level of immune response elicited, as well as methods of manipulating the response towards the most appropriate immune mechanism for any particular disease. Specifically, better methods of inducing both cellular and mucosal responses are required that must fit within the practical limitations of livestock management practices. In addition, a primary goal of vaccine research has been the provision of protective immunity with extended duration of response after only a single dose of vaccine. This goal is now most important for the effective application of anti-fertility vaccines. While a large body of vaccine research aims to find suitable target antigens, the use of these antigens must be combined with appropriate methods of vaccine delivery to ensure optimal efficacy. Vaccine development studies routinely optimise antigen dose, route and timing of delivery as well as use of adjuvants. Aluminium hydroxide remains the most widely used vaccine adjuvant in livestock species. It is used universally for combined clostridial vaccines in sheep and cattle and a range of other killed vaccines against viral and bacterial antigens. This adjuvant is primarily an inducer of antibody of the IgG1 class and has limited efficacy for inducing cellular immunity (Cox and Coulter, 1997). It does, however, have an excellent safety record and induces minimal site reactions except for the occasional occurrence of sterile abscesses at the injection site (Gupta et al., 1993). For vaccines that require strong antibody responses or cellular immunity, mineral oil emulsion adju-
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
245
vants are often used commercially in livestock provided that they fulfil defined safety requirements. Although granulomas at the injection site may also occur subsequent to administration of a mineral oil based vaccine, there is evidence that this results in enhanced immunity by providing an antigen depot (Lascelles et al., 1989). Quil A, a purified derivative of saponin, has also been used as a commercial adjuvant in some vaccines. In addition, Immunostimulating Complexes (ISCOMS) have been widely applied to experimental veterinary vaccines and their use has been reviewed elsewhere (Bowersock and Martin 1999).
6. Controlled antigen release —potential for single dose vaccination In recent years, developments in drug delivery for the pharmaceutical industry have provided methods for controlled release of antigen over long periods. These new methods of manipulating antigen delivery have potential to allow single-dose vaccination and may prove to be of particular benefit for anti-fertility vaccines that require extended duration of antibody response. Early studies in immunology have suggested that pulsatile antigen delivery was required for induction of immunity while continuous antigen delivery resulted in immune tolerance. Analysis of these studies have shown that repeated multiple injections were used, as no suitable method of long term antigen delivery was available, and that poor antigens were often used, in the absence of adjuvant. There are now sufficient data available to demonstrate that immunity can indeed be induced by continuous antigen release when delivered appropriately, using vehicles that preserve the integrity of the antigen. These methods are summarised in Table 1. The influence of varying antigen release profiles on the size and type of the ensuing immune response, however, is yet to be understood. Microspheres have been most widely tested as vaccine delivery vehicles, with polymers, particularly polylactide-co-glycolide (PLGA) being most commonly used for their production. Microspheres offer the advantage of being injectable, and the release rate of antigen may be modified either by varying the particle size or the ratio of polymers used in their production (lactic acid:glycolic acid). In addition, microspheres may be applied via the oral or nasal route for induction of mucosal immune responses (McDermott et al., 1998). While a pulsatile release profile may be theoretically elicited by use of two different size or density microspheres, there is effectively two populations of particles whose release profiles are likely to overlap, resulting in varied but continuous antigen release. Problems associated with use of some polymer microspheres include the use of extremes of temperature or
In vitro
Mice, Sheep
Mice
Newcastle disease vaccine
Ovalbumin
Human gamma globulin
Bovine serum albumin
Avidin/IL-1b Bovine serum albumin
Recombinant Dichelobacter nodosus antigen/Quil A
Avidin, C. tetanus and C.no6yi toxoids/rovIL-1b
BSA, g-globulin, ribonuclease
Alginate microsphere
Gelatin Microsphere
Osmotic pump
Silicone implant Cholesterol implant
Cholesterol/lecithin implant
Collagen minipellet
Ethylene-vinyl acetate co-polymer implant
Sheep
Mice Mice
Mice
Mice
Cattle
Mice
Human serum albumin
Mice
Ovalbumin
Polymer grafted starch microsphere Chitosan microsphere
Guinea pigs
Tetanus toxoid/rehydragel
PLGA microsphere
Species
Antigen/adjuvant
Delivery method
Table 1 Delivery systems for controlled antigen release
High neutralising antibody titres High antibody titres maintained for \1 year IgG responses compared with soluble Chemical modification provided range of release rates in vitro Mucosal responses recorded at lung; optimal responses from subcutaneous priming and oral booster IgG and DTH responses induced Equivalent antibody response to multiple injections High antibody titres Antibody response exceeded that induced by three doses Antibody response equivalent to two doses administered in Quil A Implant vaccination induced antibody responses exceeding alum-adjuvanted vaccination in mice, and equivalent to alum-adjuvanted vaccination in sheep Elevated antibody titres for 6 months, IgG
Results
Preis and Langer, 1979
Lofthouse et al., 2001
Kajihara et al., 1999 Opdebeeck and Tucker, 1993 Walduck et al., 1998
Walduck and Opdebeeck, 1997
Nakaoka et al., 1995
Bowersock et al., 1998
Heritage et al., 1996; McDermott et al., 1998 Mi et al., 1999
Coombes et al., 1996
Johansen et al., 1998
Reference
246 S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
247
pH, and organic solvents during production, as well as the in vivo breakdown into acidic by-products that may adversely affect antigen stability. In addition, polymers are often too expensive to be used for routine livestock vaccination. Modified production methods (Audran et al., 1998; Johansen et al., 1998; Tracy, 1998) and use of alternative materials including alginate (Bowersock et al., 1998, 1999), starch (Heritage et al., 1996; McDermott et al., 1998), gelatin (Nakaoka et al., 1995) and chitosan (Mi et al., 1999) are currently being investigated to overcome these problems. An alternative delivery method is the use of injectable implants impregnated with antigen and/or adjuvant. This method was first demonstrated in 1979 by Preis and Langer (Preis and Langer, 1979) who used ethylene vinyl acetate co-polymer to induce antibody titres in mice that exceeded those induced by two injections of antigen in Freund’s complete adjuvant for over 6 months. A range of alternative implant excipients including cholesterol (Opdebeeck and Tucker, 1993), cholesterol/lecithin (Walduck et al., 1998), collagen (Lofthouse et al., 2001; Fujioka et al., 1995a) and silicone (Kajihara et al., 2000) have since been examined. In our laboratory we have investigated both degradable collagen implants and non-degradable silicone implants as vaccine delivery vehicles. These implants were developed by Sumitomo Pharmaceutical Co. Ltd., Japan, for the delivery of protein pharmaceuticals, particularly cytokines (Fujiwara et al., 1990; Fujioka et al., 1995b). Our studies were conducted in both mice (Kajihara et al., 1999) and sheep (Kemp et al., 2002), using the model antigen avidin and Clostridium tetanus and C. no6yi toxoids combined with recombinant ovine interleukin-1b (rovIL-1b), a cytokine whose adjuvant properties has been previously demonstrated in sheep (Andrews et al., 1994). A range of implants was tested that released antigen over a range of time periods with different delivery profiles. Although all implants tested were shown to be able to induce antibody responses equivalent to that induced by conventional vaccination (two injections of antigen in alum adjuvant; Lofthouse et al., 2001), the ‘silicone covered rod’ implant showed most potential for use as a single-dose vaccine delivery vehicle. RovIL-1b was used as an adjuvant due to the need for provision of implant raw materials that could be freeze (or spray) dried. In addition, the small size of the implant (2 mm diameter×10 mm length) was ideal for delivery of cytokine adjuvants that are active at very low doses. When avidin was released from the silicone covered rods with rovIL-1b adjuvant, a single administration maintained antibody titres at a level significantly exceeding that induced by two equivalent doses of avidin injected with alum adjuvant. In addition, the antibody induced was of high affinity and comprised both sheep IgG isotypes, IgG1 and IgG2, with the IgG2 response induced being two-fold higher than that induced by conventional vaccina-
248
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
tion. After antigenic challenge of vaccinated sheep, an improved memory response was also evident in sheep vaccinated with the single covered rod compared with conventionally vaccinated controls. These data are summarised in Figs. 1–3 and further described in Kemp et al. (2002). The responses elicited by the covered rod implant were entirely dependent on the inclusion of adjuvant into the implant formulation. Implants that delivered antigen only induced antibody responses equivalent to those induced by antigen delivered in saline alone, indicating that slow release of antigen was in itself not capable of enhancing the immune response. Immune responses elicited were primarily antibody mediated, making the implants an ideal vehicle for delivery of clostridial toxoids. Vaccination studies in sheep using C. tetanus and C. no6yi toxoids confirmed the superiority of the covered rod implant over conventional alum-adjuvanted vaccination, with neutralising titres induced by the covered rod implants being up to three-fold higher than for the conventionally vaccinated control animals (Lofthouse, unpublished results). Further studies are being conducted using different adjuvants to attempt to modulate the type of response elicited by implant vaccination.
Fig. 1. Avidin-specific antibody responses elicited in sheep by vaccination with either a single administration (subcutaneous) at day 0, of a silicone covered rod adjuvanted with rovIL-1b ( ), or two doses of avidin in alum adjuvant delivered at days 0 and 28 by subcutaneous injection ( ). The arrow indicates the time of secondary administration of antigen to the injected group. Group serum pools were titrated at each time point to determine the 50% response titre (n=7).
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
249
Fig. 2. Avidity of avidin-specific antibody elicited in sheep 14 days after a single vaccination with avidin and rovIL-1b in implants, or avidin in alum injected subcutaneously. The covered rod implant delivers antigen in vitro in a zero order (constant daily rate) profile for several months. The matrix implant delivers antigen in vitro in a first order (reducing rate) for 1 month. The inverse avidity index was determined by binding inhibition ELISA; higher inverse avidity index indicates higher avidity. Group serum pools were used (n =7).
While there are significant opportunities to improve animal production by manipulating the immune response for a variety of biological systems, the specific developments in this area must be met by improvements in basic vaccine technologies that will allow these new approaches to be most effective under field conditions. The importance of vaccine delivery cannot be underestimated. Although experimental systems have demonstrated the potential for induction of cellular and mucosal responses, and the ability to improve and extend the immune response elicited, further studies are required to develop these methods into practical vaccine delivery strategies that will complement existing animal management practices and fulfil safety requirements. The recent advent of controlled release methods such as those described above, and other novel techniques of antigen delivery such as DNA vaccination (reviewed in Watts and Kennedy, 1999) offers potential for the production of single dose vaccines which will greatly enhance the use of these products in livestock industries.
250
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
Fig. 3. Isotype-specific anti-avidin antibody responses elicited in sheep 69 days after either a single administration of the covered rod implant adjuvanted with rovIL-1b, or two injections of avidin in alum injected subcutaneously. Both sheep IgG isotypes are shown; IgG1 (solid bars) and IgG2 (hashed bars). Group serum pools were used in an ELISA assay.
References Andrews, A., Lofthouse, S., Bowles, V.M., Brandon, M.R., Nash, A.D., 1994. Production and in vivo use of recombinant ovine IL-1b as an immunological adjuvant. Vaccine 12, 14 –22. Arimura, A., Sato, H., Kumasaka, T., Worobec, R.B., Debeljuk, L., Dunn, J., Schally, A.V., 1973. Production of antiserum to LH-releasing hormone (LH-RH) associated with gonadal atrophy in rabbits: development of radioimmunoassays for LH-RH. Endocrinology 93, 1092 –1103. Audran, R., Men, Y., Johansen, P., Gander, B., Corradin, G., 1998. Enhanced immunogenicity of microencapsulated tetanus toxoid with stabilizing agents. Pharm. Res. 15, 1111 –1116. Bain, R., 1999. Irradiated vaccines for helminth control in livestock. Int. J. Parasitol. 29, 185 –191. Baird, D., 2000. Overview of advances in contraception. Br. Med. Bull. 56, 704 –716. Bonneau, M., Denmat, M.L., Vaudelet, J.C., Veloso Nunes, J.R., Mortensen, A.B., Mortensen, H.P., 1992. Contributions of fat androstenone and skatole to boar taint: I. Sensory attributes of fat and pork meat. Livestock Prod. Sci. 32, 63 –80.
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
251
Bowersock, T.L., Martin, S., 1999. Vaccine delivery to animals. Adv. Drug Delivery Rev. 38, 167 –194. Bowersock, T.L., HogenEsch, H., Torregrosa, S., Borie, D., Wang, B., Park, H., Park, K., 1998. Induction of pulmonary immunity in cattle by oral administration of ovalbumin in alginate microspheres. Immunol. Lett. 60, 37 – 43. Bowersock, T.L., HogenEsch, H., Suckow, M., Guimond, P., Martin, S., Borie, D., Torregrosa, S., Park, H., Park, K., 1999. Oral vaccination of animals with antigens encapsulated in alginate microspheres. Vaccine 17, 1804 –1811. Bradley, M., Eade, J., Penhale, J., Bird, P., 1999. Vaccines for fertility regulation of wild and domestic species. J. Biotechnol. 73, 91 – 101. Coombes, A.G., Lavelle, E.C., Jenkins, P.G., Davis, S.S., 1996. Single dose, polymeric, microparticle-based vaccines: the influence of formulation conditions on the magnitude and duration of the immune response to a protein antigen. Vaccine 14, 1429 –1438. Cox, J.C., Coulter, A.R., 1997. Adjuvants-a classification and review of their modes of action. Vaccine 15, 248 –256. Dunshea, F., Colantoni, C., Howard, K., Jackson, P., Long, K.A., Lopaticki, S., Nugent, E.A., Simons, J.A., Walker, J., Hennessy, D.P., 2000. Vaccination of entire boars with Improvac eliminates boar taint and increases growth performance. J. Animal Sci. 83, 138. Fragoso, H., Rad, P.H., Ortiz, M., Rodriguez, M., Redondo, M., Herrera, L., de la Fuente, J., 1998. Protection against Boophilus annulatus infestations in cattle vaccinated with the B. microplus Bm86-containing vaccine Gavac. Vaccine 16, 1990 –1992. Fraser, H., Gunn, H., 1973. Effects of antibodies to luteinizing hormone-releasing hormone in the male rabbit and on the rat oestrus cycle. Nature 244, 160 – 161. Fujioka, K., Takada, Y., Sato, S., Miyata, T., 1995a. Long-acting delivery system of interferon: IFN minipellet. J. Control Release 33, 317 – 323. Fujioka, K., Takada, Y., Sato, S., Miyata, T., 1995b. Novel delivery system for proteins using collagen as a carrier material: the minipellet. J. Control. Release 33, 307 –315. Fujiwara, T., Sakagami, K., Orita, K., 1990. Antitumour effects of a new interleukin-2 slow delivery system on methylcholanthrene-induced fibrosarcoma in mice. J. Cancer Res. Clin. Oncol. 116, 141 –148. Gupta, R.K., Relyveld, E.H., Lindblad, E.B., Bizzini, B., Ben-Efraim, S., Gupta, C.K., 1993. Adjuvants-a balance between toxicity and adjuvanticity. Vaccine 11, 293 – 306. Heritage, P.L., Loomes, L.M., Jianxiong, J., Brook, M.A., Underdown, B.J., McDermott, M.R., 1996. Novel polymer-grafted starch microparticles for mucosal delivery of vaccines. Immunology 88, 162 –168. Hoskinson, R., Rigby, R., Mattner, P.E., Huynh, V.L., D’Occhio, M., Neish, A., Trigg, T.E., Moss, B.A., Lindsay, M.J., Coleman, G.D., Schwartzkoff, C.L., 1990. Vaxstrate: an anti-reproductive vaccine for cattle. Aust. J. Biotechnol. 4, 166 –170. Jago, J., Matthews, L., Trigg, T.E., Dobbie, P., Bass, J.J., 1999. The effect of immunocastration 7 weeks before slaughter on the behaviour, growth and meat quality of post-pubertal bulls. Animal Sci. 68, 163 –171. Johansen, P., Men, Y., Audran, R., Corradin, G., Merkle, H.P., Gander, B., 1998. Improving stability and release kinetics of microencapsulated tetanus toxoid by co-encapsulation of additives. Pharm. Res. 15, 1103 –1110. Johnson, K.S., Harrison, G.B., Lightowlers, M.W., O’Hoy, K.L., Cougle, W.G., Dempster, R.P., Lawrence, S.B., Vinton, J.G., Heath, D.D., Rickard, M.D., 1989. Vaccination against ovine cysticercosis using a defined recombinant antigen. Nature 338, 585 – 587. Jonsson, N.N., Matschoss, A.L., Pepper, P., Green, P.E., Albrecht, M.S., Hungerford, J., Ansell, J., 2000. Evaluation of tickGARD(PLUS), a novel vaccine against Boophilus microplus, in lactating Holstein –Friesian cows. Vet. Parasitol. 88, 275 –285.
252
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
Kajihara, M., Sugie, T., Nagahara, S., Hanai, K., Sano, A., Lofthouse, S., Nash, A., Brandon, M., 1999. Controlled release system as novel vaccination method. Proc. Int. Symp. Control Rel. Bioact. Mater. 26, 1042 – 1043. Kajihara, M., Sugie, T., Mizuno, M., Tamura, T., Sano, A., Fujioka, K., Kashiwazaki, Y., Yamaoka, T., Sugawara, S., Urabe, Y., 2000. Development of a new drug delivery system for protein drugs using silicone (I). J. Control Release 66, 49 –61. Kemp, J.M., Kajihara, M., Nagahara, S., Sano, A., Brandon, M., Lofthouse, S., 2002. Continuous antigen delivery from controlled release implants induces significant and anamnestic immune responses. Vaccine. 20, 1089 – 1098. Land, R.B., Morris, B.A., Baxter, G., Fordyce, M., Forster, J., 1982. Improvement of sheep fecundity by treatment with antisera to gonadal steroids. J. Reprod. Fertil. 66, 625 – 634. Lascelles, A.K., Eagleson, G., Beh, K.J., Watson, D.L., 1989. Significance of Freund’s adjuvant/antigen injection granuloma in the maintenance of serum antibody response. Vet. Immunol. Immunopathol. 22, 15 – 27. Lofthouse, S., Nagahara, S., Sedgmen, B., Barcham, G., Brandon, M., Sano, A., 2001. The application of biodegradable collagen minipellets as vaccine delivery vehicles in mice and sheep. Vaccine 19, 4318 –4327. McCauley, I., Cronin, G., Barnett, J.L., Butler, K.L., Hennessy, D.P., Campbell, R.G., Luxford, B., Smits, R.J., Tillbrook, A.J., Dunshea, F.R., 2000. An immunocastration vaccine (Improvac) increases growth in individually and group-housed boars. J. Animal Sci. 83, 138. McDermott, M.R., Heritage, P.L., Bartzoka, V., Brook, M.A., 1998. Polymer-grafted starch microparticles for oral and nasal immunisation. Immunol. Cell Biol. 76, 256 –262. Mi, F.L., Shyu, S.S., Chen, C.T., Schoung, J.Y., 1999. Porous chitosan microsphere for controlling the antigen release of Newcastle disease vaccine: preparation of antigen-adsorbed microsphere and in vitro release. Biomaterials 20, 1603 –1612. Nakaoka, R., Tabata, Y., Ikada, Y., 1995. Potentiality of gelatin microsphere as immunological adjuvant. Vaccine 13, 653 –661. Opdebeeck, J., Tucker, I., 1993. A cholesterol implant used as a delivery system to immunise mice with bovine serum albumin. J. Control Release 23, 271 –279. Pasteur, L., 1880. De l’attenuation du virus du cholera des poules. CR Acad. Sci. Paris 91, 673–680. Pasteur, L., Chamberland, C., Roux, R., 1881. Sur la vaccination charboneusse. CR Acad. Sci. Paris 92, 1378 –1383. Preis, I., Langer, R., 1979. A single-step immunisation by sustained antigen release. J. Immunol. Methods 28, 193 –197. Rickard, M.D., Harrison, G.B., Heath, D.D., Lightowlers, M.W., 1995. Taenia o6is recombinant vaccine —‘quo vadit’. Parasitology 110, S5 –S9. Robertson, I., Fraser, H., Innes, G.M., Jones, A.S., 1982. Effect of immunological castration on sexual and production characteristics in male cattle. Vet. Rec. 116, 74 –75. Sad, S., Gupta, H., Talwar, G.P., Raghupathy, R., 1991. Carrier-induced suppression of the antibody response to a ‘self’ hapten. Immunology 74, 223 – 227. Schetters, T., 1995. Vaccine development from a commercial point of view. Vet. Parasitol. 57, 267 –275. Thompson, D., 2000. Immunisation against GnRH in male species. Animal Reprod. Sci. 60–61, 459 –469. Tracy, M.A., 1998. Development and scale-up of a microsphere protein delivery system. Biotechnol. Prog. 14, 108 –115.
S. Lofthouse, J. Kemp / Journal of Reproducti6e Immunology 57 (2002) 239–253
253
Walduck, A., Opdebeeck, J.P., 1997. Effect of profile of antigen delivery on antibody responses in mice. J. Control. Release 43, 75 – 80. Walduck, A., Opdebeeck, J., Benson, H.E., Prankerd, R., 1998. Biodegradable implants for the delivery of veterinary vaccines: design, manufacture and antibody responses in sheep. J. Control. Release 51, 269 –280. Waller, P., 1997. Anthelmintic resistance. Vet. Parasitol. 72, 391 –412. Watts, A.M., Kennedy, R.C., 1999. DNA vaccination strategies against infectious diseases. Int. J. Parasitol. 29, 1149 –1163.