Prospects for development of vaccines against fungal diseases

Drug Resistance Updates 9 (2006) 105–110

Prospects for development of vaccines against fungal diseases Jennifer M. Dan, Stuart M. Levitz ∗ Departments of Medicine and Microbiology, Boston University School of Medicine, Boston, MA, United States Received 1 March 2006; received in revised form 9 May 2006; accepted 11 May 2006

Abstract Despite recent additions to our antifungal drug armamentarium, success rates for many mycoses remain unacceptably low and antifungal drug therapy is often limited by toxicity, resistance and high cost. To circumvent these difficulties, alternative approaches to prevention and treatment are being developed, including vaccines and passive immunotherapy. Here, we review the progress of current research in this field, discuss some of the potential obstacles to developing and marketing a protective antifungal vaccine, and summarize two clinical trials of monoclonal antibodies as adjunctive treatment of established mycoses. In animal models of fungal infections, protective responses have been elicited with vaccines composed of whole organisms, soluble cell free fractions, purified proteins, glycans and nucleic acids. Methods to boost the immune response to vaccination include the use of adjuvants and antigen-loaded dendritic cells (DCs). A significant challenge to the development of effective vaccines will be to elicit immune responses in immunocompromised individuals who are most at risk for invasive fungal infections. © 2006 Elsevier Ltd. All rights reserved. Keywords: Fungal vaccine; Passive immunotherapy; Humoral immunity; Cell-mediated immunity; Dendritic cell vaccine

1. Introduction The number of immunocompromised persons has risen sharply in the past few decades, a result of the AIDS epidemic as well as the increased use of immunosuppressive medications to treat patients with neoplasms, transplants, and autoimmune diseases. Fungal infections have emerged as major causes of morbidity and mortality in this population, most commonly those due to Aspergillus species, Pneumocystis jirovecii (formerly Pneumocystis carinii), Cryptococcus neoformans, and Candida species. In addition, other medically important fungi, particularly the geographically restricted dimorphic fungi, Histoplasma capsulatum, Blastomyces dermatitidis, Paracoccidioides brasiliensis, and Coccidioides species, afflict both immunocompetent and immuncompromised persons. Current antifungal regimens form a limited armamentarium consisting mainly of those relying on the few differences existing between eukaryotic fungal and mammalian cells. ∗

Correspondence to: Section of Infectious Diseases, 650 Albany Street, Boston University Medical Center, Boston, MA 02118, United States. Tel.: +1 617 638 7904; fax: +1 617 638 7923. E-mail address: [email protected] (S.M. Levitz). 1368-7646/$ – see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.drup.2006.05.004

The classes available for systemic use include: polyenes (amphotericin B) which target ergosterol, a fungal cell membrane sterol, to create membrane spanning channels; azoles (fluconazole, itraconazole, voriconazole, posaconazole) and allylamines (terbinafine) which target ergosterol enzymatic synthesis; echinocandins (caspofungin, micafungin) which target synthesis of the cell wall polysaccharide, ␤-1,3-glucan; and flucytosine, an anti-metabolite of DNA and RNA synthesis (Anderson, 2005). Unfortunately, success rates for many mycoses remain unacceptably low and drug therapy is often limited by toxicity, resistance and cost (Richardson, 2005). Clearly, new strategies are needed to prevent at risk patients from acquiring fungal infections and for adjunctive therapy of patients with established mycoses. Attractive approaches include vaccination and passive immunotherapy. Below we review the progress of current research in this field and discuss some of the potential obstacles to developing and marketing a protective antifungal vaccine.

2. Passive immunotherapy Passive immunotherapy entails the use of antibodies to neutralize an infection without inducing an active mem-

106

J.M. Dan, S.M. Levitz / Drug Resistance Updates 9 (2006) 105–110

ory immune response by the host. Two antifungal monoclonal antibodies have been tested in clinical trials for passive immunotherapy. Mycograb® is a recombinant antifungal human monoclonal antibody that was developed from a protective antibody purified from the bloodstream of a patient with invasive candidiasis. Mycograb® binds to the immunodominant epitope, heat shock protein 90 (hsp90), a stressinduced cellular chaperone which is highly conserved within Candida species (Matthews and Burnie, 2004). It consists only of the variable regions of the heavy and light chains. Mycograb® , in combination with amphotericin B, was compared with amphotericin B alone in a multicenter double blind placebo-controlled trial of patients with invasive candidiasis. The group that received combination treatment demonstrated 84% complete mycological resolution and clinical response compared to 48% of patients receiving amphotericin B alone (Pachl et al., 2006). However, nowadays few clinicians use amphotericin B as primary therapy for invasive candidiasis. Thus, it would be important to study the clinical efficacy of Mycograb® in combination with members of the more commonly used azole and echinocandin classes of antifungals such as fluconazole and caspofungin. As C. neoformans and Aspergillus species possess hsp90 homologs, another potential application for Mycograb® is combination therapy for cryptococcosis and aspergillosis (Matthews and Burnie, 2004). The second antibody which underwent phase I clinical trials is 18B7, a mouse monoclonal antibody (MAb) reactive with the C. neoformans capsular polysaccharide component, glucuronylxylomannan (GXM) (Larsen et al., 2005). This MAb had been shown to be protective in animal models of cryptococcosis (Mukherjee et al., 1993). In addition, to presenting an antiphagocytic surface, shed capsule is immunosuppressive and accumulates in the blood and cerebrospinal fluid (CSF) of patients with cryptococcosis (Diamond and Bennett, 1974). Thus, anticapsular antibody therapy could be beneficial by promoting opsonophagocytosis of whole fungi and/or clearance of shed GXM. In order to determine a maximum tolerated dose, 18B7 was studied in HIV positive patients who had recovered from cryptococcal meningitis but still had measurable titers of capsule (cryptococcal antigen) in their blood. In the cohorts who received the higher doses of MAb, serum cryptococcal antigen titers had modest declines, but subsequently returned toward the baseline values by week 12. However, serious adverse events occurred at the highest dose. Moreover, antibody therapy stimulated HIV replication in some patients, as measured by an increase in the HIV viral load. Another side effect was the development of human antimouse antibodies in 10% of patients, an effect which must be considered when using mouse monoclonal antibody therapy (Larsen et al., 2005). While the authors are unaware of any plans for further clinical trials with MAb 18B7, an alternative use for MAb 18B7 is radioimmunotherapy in which a fungicidal radioactive isotope is linked to MAb 18B7. Radiolabeled MAb 18B7 has shown benefits in vivo in mice, with a significant prolongation of survival, a reduced organism burden,

and the ability to elicit protection even 24 h post infection (Dadachova et al., 2003). Additionally, passive antibody-mediated protection has been demonstrated in murine models of histoplasmosis and candidiasis (Nosanchuk et al., 2003). MAbs generated against histone 2B, a protein expressed on the surface of H. capsulatum yeasts, promoted opsonsophagocytosis and killing of yeasts via a complement receptor 3 (CR3)-dependent process (Nosanchuk et al., 2003). Treatment with the MAb prolonged survival and reduced yeast lung burden in infected mice. Passive immunotherapy has also been shown to protect mice against experimental candidiasis (Mourad and Friedman, 1968). Administration of either IgM or IgG3 MAb specific for fungal cell surface ␤-1,2-mannotriose elicited protection in both invasive (intraperitoneally) and mucosal (vaginitis) models of candidiasis (Han et al., 2000). A novel application of passive immunotherapy is the transphyletic use of killer toxins. The yeast Pichia anomala produces a killer toxin (KT) which interacts with ␤-glucans prevalent within the cell walls of fungi and has in vitro activity against several fungi (Magliani et al., 2005). Anti-idiotypic KT antibodies were created by immunizing animals with KT (Polonelli and Morace, 1987). Use of these antibodies in vivo demonstrated protection in models of vaginal candidiasis and P. carinii pneumonia (Magliani et al., 2005). Moreover, a synthetic decapeptide, designated killer peptide, derived from a portion of the complementarity determining region of the anti-idiotypic antibody, had considerable fungicidal activity in vitro and in vivo against C. albicans, C. neoformans, and P. brasiliensis (Magliani et al., 2005). Finally, passive immunotherapy of fungal infections has not been limited to just humoral factors as adoptive transfer of antigen-specific T cells protected mice in numerous mouse models of fungal infections (Mody et al., 1994). However, applying these findings to human mycoses will be difficult because T cells are MHC-restricted.

3. Vaccination to induce humoral immunity Research with active immunization to promote humoral immunity has focused on cell surface structures. Han et al., as discussed above, have shown protective antibody production in mouse models using a phosphomannoprotein isolated from the cell wall of C. albicans, delivered via either a liposome or conjugated to a protein carrier and administered with an adjuvant (Han et al., 2001). To create a broader antifungal coverage vaccine, Torosantucci et al. took advantage of the fact that ␤-(1,3)-glucans decorate the surface of many fungal pathogens including species of Candida and Aspergillus. Mice immunized with a vaccine composed of laminarin, a ␤-(1,3)-glucan from the brown alga Laminaria digitata, conjugated to diphtheria toxoid developed a protective IgG immune response against lethal infections of C. albicans and A. fumigatus (Torosantucci et al., 2005). However, it should be appreciated that in laboratory mice C. albicans is not a

J.M. Dan, S.M. Levitz / Drug Resistance Updates 9 (2006) 105–110

commensal. Thus, when formulating a prophylactic vaccine in humans for C. albicans, the possibility of a hyperimmune response must be considered, particularly in the gut (Mochon and Cutler, 2005). Antibodies have also been created against GXM, the main component of C. neoformans capsule. A conjugate vaccine composed of GXM covalently linked to tetanus toxoid elicited a mixture of non-protective and protective antibodies when administered to mice (Devi et al., 1991). The protective antibodies specific to GXM were then isolated and used to create peptide mimetics as potential vaccine candidates when conjugated to different protein carriers (May et al., 2003). More recently, Oscarson et al. synthesized oligosaccharide structures which represent highly immunogenic repeats of GXM and induced memory immune responses in mice when conjugated to a protein carrier and administered with an adjuvant (Oscarson et al., 2005). These studies, although preliminary, represent a more directed approach to generation of protective IgGs.

4. Vaccination to induce cell-mediated immunity Opportunistic fungal pathogens cause infections most commonly in persons with defects in cell-mediated immunity, as seen most predominantly in AIDS patients. Thus, research efforts have focused on development of protective fungal vaccines that stimulate antigen-specific T cell responses. Generating an effective T helper cell, type 1 (Th1) response and the release of the cytokines interleukin-12 (IL-12), interferongamma (IFN-␥), and tumor necrosis factor alpha (TNF-␣) are necessary for robust killing of fungi (Romani, 2004). A variety of vaccination strategies designed to elicit or boost protective cell-mediated immune responses have been tested in murine models, including whole organisms, crude antigen preparations, and purified or recombinant antigens. Whole organism vaccinations have been studied in the geographically restricted dimorphic fungi. In a phase III clinical trial evaluating formaldehyde-killed Coccidioides immitis spherules as a vaccine candidate, toxic side effects, mainly in the form of severe local reactions, occurred in study participants, necessitating a reduction of the vaccine dosage (Pappagianis, 1993). Klein et al. demonstrated that a live, attenuated form of B. dermatitidis, deficient in the virulence gene BAD1, protected mice against a lethal challenge with a virulent strain of the fungus (Klein, 2000). BAD1 is an important receptor for adhesion and for inhibition of TNF-␣ production (Finkel-Jimenez et al., 2001). The bad1 mutant elicited sterilizing immunity, CD8+ T cells memory responses and pro-inflammatory cytokines (Wuthrich et al., 2003). Likewise, mice who were vaccinated subcutaneously (s.c.) with H. capsulatum followed by CD4+ T cell depletion exhibited protection from a lethal intransal (i.n.) infection (Wuthrich et al., 2003). These studies demonstrate that in models of blastomycoses or histoplasmosis CD4+ T cell immunity is dispensable provided CD8+ T cell immunity is

107

boosted. A vaccine strategy that targets CD8+ T cells for protective immunity could prove particularly beneficial for AIDS patients, as their underlying immunodeficiency may preclude CD4+ T cell-mediated protective responses. Other vaccines created from crude soluble antigenic fractions have also demonstrated cell-mediated protection. A vaccine composed of crude antigens from the aquatic funguslike organism, Pythium insidiosum, has been developed for use in humans and equines with pythiosis. This is a rare disease that usually presents with cutaneous and vasculitic lesions. Because existing treatments are rarely curative, an immunotherapeutic approach was tried. Treatment with vaccination plus surgical debridement resulted in disease remission in 50% of the infected patients (Wanachiwanawin et al., 2004). Successful treatment was associated with a shift from a Th2 response in infected tissues to a Th1 response (Mendoza and Newton, 2005). Similarly, for murine models, subcutaneously administered soluble antigenic fractions from H. capsulatum emulsified with complete Freund’s adjuvant protected mice from a lethal challenge. This protection was linked to the in vitro production of interferon-gamma (IFN-␥) from immune mice (Sa-Nunes et al., 2005). As for C. neoformans infection, both the mannoprotein and nonmannosylated fractions of culture filtrates, when administered intraperitoneally with Ribi adjuvant, partially protected mice (Mansour et al., 2004). Due to problems with purifying native antigens from fungi, many laboratories have turned towards recombinant production of specific T cell-stimulating vaccine candidates. A synthesized 15 amino acid peptide isolated from P. brasiliensis glycoprotein 43 (gp43), a protein recognized by the sera of infected patients, was used to vaccinate (s.c.) mice. The preparation elicited interleukin-2 (IL2) and IFN-␥ mediated protection following a lethal intratracheal dose (Taborda et al., 2004). Others have utilized bacteria for production of recombinant proteins. When combined with CpG as an adjuvant, subcutaneous vaccination of mice with recombinant Escherichia coli-derived GEL1, an immundominant glycosylphosphatidylinositol-anchored ␤1,3-glucanosyltransferase of C. posadasii, increased survival of mice with experimental coccidioidomycosis (Delgado et al., 2003). Vaccinated mice had decreased colony forming units (CFUs) in the lungs and spleen. Another recombinant E. coli-derived protein, PEP1, which is expressed in both culture supernatants and in cell wall extracts, promoted a significant increase in survival when administered in combination with CpG (Tarcha et al., 2006). Using a proteomics approach, PEP1 was identified and found to be reactive with serum pooled from ten patients with confirmed coccidioidal infections (Tarcha et al., 2006). Similarly, vaccination with recombinant E. coli-derived H. capsulatum hsp60 protected mice challenged with a lethal intranasal inoculum (Gomez et al., 1995). Protection required IFN-␥ and IL-12 (Deepe and Gibbons, 2002). Fungi have also been used to create recombinant proteins, and have the potential advantage of containing immunoen-

108

J.M. Dan, S.M. Levitz / Drug Resistance Updates 9 (2006) 105–110

hancing glycosylation patterns present in the native proteins (Lam et al., 2005). A vaccine containing the extracellular portion of the C. albicans adhesin, ALS1, expressed in Saccharomyces cerevisiae promoted a protective Th1 immune response in neutropenic and non-neutropenic murine models of invasive candidiasis (Ibrahim et al., 2005; Spellberg et al., 2005). Utilizing two-dimensional differential in-gel electrophoresis coupled with nano-high-performance liquid chromatography-tandem mass spectrometry, a spheruleabundant protein of C. posadasii, peroxisomal membrane protein (Pmp1), was identified. Mice vaccinated intradermally with S. cerevisiae-derived Pmp1, when administered with immunostimulatory oligonucleotide sequences, demonstrated significant protection from an intranasal challenge with C. posadasii (Orsborn et al., 2006).

DC vaccination has also been used to induce humoral responses. Adenovirus-mediated transduction of DCs with CD40L, a marker normally expressed on activated CD4+ T cells, equipped DCs with the capacity to target na¨ıve B cells. CD40L+ DCs pulsed with P. carinii cysts provided antibodymediated protection, restricted to a 55 kDa surface-expressed protein, in CD4+ T cell deficient mice (Zheng et al., 2001). A DNA vaccine was created containing the cDNA of this 55 kDa protein plus murine CD40L encoded into the plasmid. Intramuscular injection of the DNA vaccine into CD4+ deficient mice resulted in production of anti-P. carinii IgG, allowing for opsonophagocytosis (Zheng et al., 2005). This is another example of a potential vaccine for immunocompromised patients in which boosting one arm of the immune system is used to compensate for defective function in another arm.

5. Dendritic cell vaccination 6. Conclusions Because dendritic cells (DCs) provide an interface between innate and adaptive immunity, they can serve as a unique vehicle for vaccination. DCs are potent antigenpresenting cells which take up antigen in tissue and then migrate to draining lymph nodes where they present the antigen to T cells. This allows for antigen-specific proliferation of these T cells and a subsequent cell-mediated immune response. Clinical trials have been carried out using DCs loaded ex vivo with tumor antigens for the treatment of human neoplasms (Banchereau and Palucka, 2005). This concept has also been applied with microbial antigens, including those derived from pathogenic fungi. Using yeasts to pulse DCs or RNA isolated from yeasts to transfect DCs, mice vaccinated subcutaneously generated a Th1 response with IFN-␥ production when infected with a lethal inoculum (i.v.) of C. ablicans (Bacci et al., 2002). It is important to note that in this study DC vaccination generated little to no Th1 protection when administered intravenously. This emphasizes that the response to DC vaccination can depend on the delivery method and booster schedule. Intravenous injection leads to DC localization in the reticuloendothelial system and the lungs, whereas subcutaneous injection targets DCs to the lymphatic system (Eggert et al., 1999). When administered subcutaneously, DC vaccination yielded a Th1 response. Subcutaneous DC vaccination was evaluated in a murine model following a lethal challenge (i.v.) with A. fumigatus. DCs which were either conidia-pulsed or transfected with conidia-derived RNA generated a Th1 response, with IFN-␥ production and reduced A. fumigatus CFUs (Bozza et al., 2003). In similar studies with C. albicans and A. fumigatus, protection was observed in a murine model of allogenic bone marrow transplant, with both donor and recipient DCs contributing to T cell reconstitution (Bacci et al., 2002; Bozza et al., 2003). Thus, it has been suggested that DC vaccination could be used to protect hematopoietic transplant patients from invasive aspergillosis and candidiasis by compensating for their defective T cell response.

In experimental models, protection against mycoses has been induced by vaccinating with whole organisms, cell free antigens, and antigen-pulsed DCs (Table 1). Due to concerns about toxicity and induction of autoimmune responses, vaccines composed of attenuated fungi, killed organisms or crude antigenic fractions are unlikely to be developed for clinical use in humans. However, vaccines composed of single antigens may have limited efficacy because few fungi have a single immunodominant epitope that can be targeted. Thus, effective vaccines might need to be composed of a combination of defined antigens. Additionally, the role of adjuvants, particularly in eliciting cell-mediated immunity, needs to be further assessed, as antigens require “help” to induce host immunity. While most Food and Drug Administration approved adjuvants, including alum, skew towards a Th2 response, further development of Th1-skewing adjuvants such as CpG may aid in generating host protection. Moreover, because few antigens are present on the majority of pathogenic fungi, it may be difficult to develop an “all inclusive” fungal vaccine that protects against the range of mycotic infections encountered in clinical practice. One promising target is cell wall glycans, such as ␤-glucans, which are conserved among the fungal genera. A significant challenge to the development of effective vaccines will be to elicit immune responses in immunocompromised individuals who are most at risk for invasive fungal infections. For fungi such as the ubiquitious A. fumigatus, an immunoprophylatic agent could be feasible for solid organ transplantation and chemotherapy, as the time of immunosuppression is known (Feldmesser, 2005). However, for a person with AIDS and few CD4+ T cells, a vaccine that targets CD4+ T cell immunity is unlikely to be truly effective. Rather, approaches that target components of the immune systems that are relatively intact, such as CD8+ T cells, are more likely to be successful. For those mycoses that occur with regularity in the immunocompetent, such as coccidioidomy-

J.M. Dan, S.M. Levitz / Drug Resistance Updates 9 (2006) 105–110

109

Table 1 Summary of selected studies organized according to methodology Methodology

Examples

Whole organism

bad1 mutant for B. dermatitidis Formaldehyde-killed spherules for C. immitis

Soluble antigenic fractions Total

P. insidiosum in humans and equines H. capsulatum

Soluble antigenic fractions

GXM-tetanus toxoid to induce IgG; GXM peptide mimetics to induce IgG

Surface associated

␤-(1,3)-glucan from Laminaria digitata for A. fumigatus and C. albicans Mannoprotein fraction from C. neoformans Mouse monoclonal antibody against histone 2B for H. capsulatum

Recombinant proteins

Synthetic 15 amino acid peptide from gp43 for P. brasiliensis E. coli-derived GEL1 and PEP1 of C. posadasii E. coli-derived hsp60 for H. capsulatum S. cerevisiae-derived ALS1 for C. albicans S. cerevisiae-derived Pmp1 for C. posadasii

Dendritic cell vaccine

Pulse with whole organisms for C. albicans and A. fumigatus Transfect with RNA for C. albicans and A. fumigatus Pulse with cysts or cDNA transfection for P. carinii

Passive immunotherapy

Variable heavy and light chains against hsp90 for C. albicans (Mycograb® ) Mouse monoclonal antibody against GXM from C. neoformans capsule (18B7) MAb against histone 2B for H. capsulatum IgM and IgG3 against the phosphomannan complex of C. albicans

cosis and histoplasmosis, a vaccine will need to be highly efficacious with little toxicity in order to gain widespread acceptance. Despite these aforementioned formidable obstacles, creation of efficacious fungal vaccines needs to be vigorously pursued as it promises to reduce the disease burden caused by mycoses as well as decrease antifungal costs and resistance.

Acknowledgments This work was supported in part by National Institutes of Health grants RO1 AI25780, RO1 AI066087, and T32 AI07642.

References Anderson, J.B., 2005. Evolution of antifungal-drug resistance: mechanisms and pathogen fitness. Nat. Rev. Microbiol. 3, 547–556. Bacci, A., Montagnoli, C., Perruccio, K., Bozza, S., Gaziano, R., Pitzurra, L., Velardi, A., d’Ostiani, C.F., Cutler, J.E., Romani, L., 2002. Dendritic cells pulsed with fungal RNA induce protective immunity to Candida albicans in hematopoietic transplantation. J. Immunol. 168, 2904–2913. Banchereau, J., Palucka, A.K., 2005. Dendritic cells as therapeutic vaccines against cancer. Nat. Rev. Immunol. 5, 296–306. Bozza, S., Perruccio, K., Montagnoli, C., Gaziano, R., Bellocchio, S., Burchielli, E., Nkwanyuo, G., Pitzurra, L., Velardi, A., Romani, L., 2003. A dendritic cell vaccine against invasive aspergillosis in allogeneic hematopoietic transplantation. Blood 102, 3807– 3814. Dadachova, E., Nakouzi, A., Bryan, R.A., Casadevall, A., 2003. Ionizing radiation delivered by specific antibody is therapeutic against a fungal infection. Proc. Natl. Acad. Sci. U.S.A. 100, 10942–10947.

Deepe, G.S., Gibbons, R.S., 2002. Cellular and molecular regulation of vaccination with heat shock protein 60 from Histoplasma capsulatum. Infect. Immun. 70, 3759–3767. Delgado, N., Xue, J.M., Yu, J.J., Hung, C.Y., Cole, G.T., 2003. A recombinant beta-1,3-glucanosyltransferase homolog of Coccidioides posadasii protects mice against coccidioidomycosis. Infect. Immun. 71, 3010–3019. Devi, S.J.N., Schneerson, R., Egan, W., Ulrich, T.J., Bryla, D., Robbins, J.B., Bennett, J.E., 1991. Cryptococcus neoformans serotype – a glucuronoxylomannan-protein conjugate vaccines – synthesis, characterization, and immunogenicity. Infect. Immun. 59, 3700–3707. Diamond, R.D., Bennett, J.E., 1974. Prognostic factors in cryptococcal meningitis. A study in 111 cases. Ann. Intern. Med. 80, 176–181. Eggert, A.A.O., Schreurs, M.W.J., Boerman, O.C., Oyen, W.J.C., de Boer, A.J., Punt, C.J.A., Figdor, C.G., Adema, G.J., 1999. Biodistribution and vaccine efficiency of murine dendritic cells are dependent on the route of administration. Cancer Res. 59, 3340–3345. Feldmesser, M., 2005. Prospects of vaccines for invasive aspergillosis. Med. Mycol. 43, 571–587. Finkel-Jimenez, B., Wuthrich, M., Brandhorst, T., Klein, B.S., 2001. The WI-1 adhesin blocks phagocyte TNP-alpha production, imparting pathogenicity on Blastomyces dermatitidis. J. Immunol. 166, 2665–2673. Gomez, F.J., Allendoerfer, R., Deepe, G.S., 1995. Vaccination with recombinant heat-shock protein-60 from Histoplasma Capsulatum protects mice against pulmonary histoplasmosis. Infect. Immun. 63, 2587–2595. Han, Y., Riesselman, M.H., Cutler, J.E., 2000. Protection against candidiasis by an immunoglobulin G3 (IgG3) monoclonal antibody specific for the same mannotriose as an IgM protective antibody. Infect. Immun. 68, 1649–1654. Han, Y.M., Kozel, T.R., Zhang, M.X., MacGill, R.S., Carroll, M.C., Cutler, J.E., 2001. Complement is essential for protection by an IgM and an IgG3 monoclonal antibody against experimental, hematogenously disseminated candidiasis. J. Immunol. 167, 1550–1557. Ibrahim, A.S., Spellberg, B.J., Avenissian, V., Fu, Y., Filler, S.G., Edwards, J.E., 2005. Vaccination with recombinant N-terminal domain of Als1p improves survival during murine disseminated candidiasis by

110

J.M. Dan, S.M. Levitz / Drug Resistance Updates 9 (2006) 105–110

enhancing cell-mediated, not humoral, immunity. Infect. Immun. 73, 999–1005. Klein, B.S., 2000. Molecular basis of pathogenicity in Blastomyces dermatitidis: the importance of adhesion. Curr. Opin. Microbiol. 3, 339–343. Lam, J.S., Mansour, M.K., Specht, C.A., Levitz, S.M., 2005. A model vaccine exploiting fungal mannosylation to increase antigen immunogenicity. J. Immunol. 175, 7496–7503. Larsen, R.A., Pappas, P.G., Perfect, J., Aberg, J.A., Casadevall, A., Cloud, G.A., James, R., Filler, S., Dismukes, W.E., 2005. Phase I evaluation of the safety and pharmacokinetics of murine-derived anticryptococcal antibody 18B7 in subjects with treated cryptococcal meningitis. Antimicrob. Agents Chemother. 49, 952–958. Magliani, W., Conti, S., Frazzi, R., Ravanetti, L., Maffei, D.L., Polonelli, L., 2005. Protective antifungal yeast killer toxin-like antibodies. Curr. Mol. Med. 5, 443–452. Mansour, M.K., Yauch, L.E., Rottman, J.B., Levitz, S.M., 2004. Protective efficacy of antigenic fractions in mouse models of cryptococcosis. Infect. Immun. 72, 1746–1754. Matthews, R.C., Burnie, J.P., 2004. Recombinant antibodies: a natural partner in combinatorial antifungal therapy. Vaccine 22, 865–871. May, R.J., Beenhouwer, D.O., Scharff, M.D., 2003. Antibodies to keyhole limpet hemocyanin cross-react with an epitope on the polysaccharide capsule of Cryptococcus neoformans and other carbohydrates: implications for vaccine development. J. Immunol. 171, 4905–4912. Mendoza, L., Newton, J.C., 2005. Immunology and immunotherapy of the infections caused by Pythium insidiosum. Med. Mycol. 43, 477–486. Mochon, A.B., Cutler, J.E., 2005. Is a vaccine needed against Candida albicans? Med. Mycol. 43, 97–115. Mody, C.H., Paine III, R., Jackson, C., Chen, G.H., Toews, G.B., 1994. CD8 cells play a critical role in delayed type hypersensitivity to intact Cryptococcus neoformans. J. Immunol. 152, 3970–3979. Mourad, S., Friedman, L., 1968. Passive immunization of mice against Candida albicans. Sabouraudia 6, 103–105. Mukherjee, J., Casadevall, A., Scharff, M.D., 1993. Molecular characterization of the humoral responses to Cryptococcus neoformans infection and glucuronoxylomannan-tetanus toxoid conjugate immunization. J. Exp. Med. 177, 1105–1116. Nosanchuk, J.D., Steenbergen, J.N., Shi, L., Deepe, G.S., Casadevall, A., 2003. Antibodies to a cell surface histone-like protein protect against Histoplasma capsulatum. J. Clin. Invest. 112, 1164–1175. Orsborn, K.I., Shubitz, L.F., Peng, T., Kellner, E.M., Orbach, M.J., Haynes, P.A., Galgiani, J.N., 2006. Protein expression profiling of Coccidioides posadasii by two-dimensional differential in-gel electrophoresis and evaluation of a newly recognized peroxisomal matrix protein as a recombinant vaccine candidate. Infect. Immun. 74, 1865–1872. Oscarson, S., Alpe, M., Svahnberg, P., Nakouzi, A., Casadevall, A., 2005. Synthesis and immunological studies of glycoconjugates of Cryptococcus neoformans capsular glucuronoxylomannan oligosaccharide structures. Vaccine 23, 3961–3972. Pachl, J., Svoboda, P., Jacobs, F., Vandewoude, K., Hoven, B., Spronk, P., Masterson, G., Malbrain, M., Aoun, M., Garbino, J., Takala, J., Drgona, L., Burnie, J., Matthews, R., 2006. A randomized, blinded,

multicenter trial of lipid-associated amphotericin B alone versus in combination with an antibody-based inhibitor of heat shock protein 90 in patients with invasive candidiasis. Clin. Infect. Dis. 42, 1404– 1413. Pappagianis, D., 1993. Evaluation of the protective efficacy of the killed Coccidioides immitis spherule vaccine in humans. The valley fever vaccine study group. Am. Rev. Respir. Dis. 148, 656–660. Polonelli, L., Morace, G., 1987. Production and characterization of yeast killer toxin monoclonal antibodies. J. Clin. Microbiol. 25, 460–462. Richardson, M.D., 2005. Changing patterns and trends in systemic fungal infections. J. Antimicrob. Chemother. 56 (Suppl. 1), i5–i11. Romani, L., 2004. Immunity to fungal infections. Nat. Rev. Immunol. 4, 11–23. Sa-Nunes, A., Medeiros, A.I., Nicolete, R., Frantz, F.G., Panunto-Castelo, A., Silva, C.L., Faccioli, L.H., 2005. Efficacy of cell-free antigens in evaluating cell immunity and inducing protection in a murine model of histoplasmosis. Microbes Infect. 7, 584–592. Spellberg, B.J., Ibrahim, A.S., Avenissian, V., Filler, S.G., Myers, C.L., Fu, Y., Edwards, J.E., 2005. The anti-Candida albicans vaccine composed of the recombinant N terminus of Als1p reduces fungal burden and improves survival in both immunocompetent and immunocompromised mice. Infect. Immun. 73, 6191–6193. Taborda, C.P., Nakaie, C.R., Cilli, E.M., Rodrigues, E.G., Silva, L.S., Franco, M.F., Travassos, L.R., 2004. Synthesis and immunological activity of a branched peptide carrying the T-cell epitope of gp43, the major exocellular antigen of Paracoccidioides brasiliensis. Scand. J. Immunol. 59, 58–65. Tarcha, E.J., Basrur, V., Hung, C.Y., Gardner, M.J., Cole, G.T., 2006. A recombinant aspartyl protease of Coccidioides posadasii induces protection against pulmonary coccidioidomycosis in mice. Infect. Immun. 74, 516–527. Torosantucci, A., Bromuro, C., Chiani, P., De Bernardis, F., Berti, F., Galli, C., Norelli, F., Bellucci, C., Polonelli, L., Costantino, P., Rappuoli, R., Cassone, A., 2005. A novel glyco-conjugate vaccine against fungal pathogens. J. Exp. Med. 202, 597–606. Wanachiwanawin, W., Mendoza, L., Visuthisakchai, S., Mutsikapan, P., Sathapatayavongs, B., Chaiprasert, A., Suwanagool, P., Manuskiatti, W., Ruangsetakit, C., Ajello, L., 2004. Efficacy of immunotherapy using antigens of Pythium insidiosum in the treatment of vascular pythiosis in humans. Vaccine 22, 3613–3621. Wuthrich, M., Filutowicz, H.I., Warner, T., Deepe, G.S., Klein, B.S., 2003. Vaccine immunity to pathogenic fungi overcomes the requirement for CD4 help in exogenous antigen presentation to CD8(+) T cells: implications for vaccine development in immune-deficient hosts. J. Exp. Med. 197, 1405–1416. Zheng, M.Q., Ramsay, A.J., Robichaux, M.B., Norris, K.A., Kliment, C., Crowe, C., Rapaka, R.R., Steele, C., McAllister, F., Shellito, J.E., Marrero, L., Schwarzenberger, P., Zhong, Q., Kolls, J.K., 2005. CD4(+) T cell-independent DNA vaccination against opportunistic infections. J. Clin. Invest. 115, 3536–3544. Zheng, M.Q., Shellito, J.E., Marrero, L., Zhong, Q., Julian, S., Ye, P., Wallace, V., Schwarzenberger, P., Kolls, J.K., 2001. CD4(+) T cellindependent vaccination against Pneumocystis carinii in mice. J. Clin. Invest. 108, 1469–1474.