- Email: [email protected]
Detection of parvovirus B19-specific IgM by antibody capture radioimmunoassay
Journal of Virological Methods
ELSEVIER
Journal of Virological Methods 66 (1997) t-4
Protocol
Detection of parvovirus B 19-specific IgM by antibody capture radioimmunoassay Bernard
John Cohen ‘,*
aEnteric and Respiratory Virus Laboratory, Virus Rejtirence Division, Central Public Health Laboratory, Colindale Avenue, London NW9 5HT. UK
Abstract
A solid phase IgM-capture radioimmunoassay (MACRIA) for the detection of parvovirus B19-IgM is described (Cohen et al., 1983, J. Hyg. Camb. 91, 113-130). IgM from a dilution of patients serum is ‘captured’ onto a solid phase coated by anti-human IgM. To determine whether any of the IgM is specific for parvovirus B19, B19 antigen is added followed by a detector system. In the MACRIA described here the detector system comprises a mouse monoclonal antibody to parvovirus B19 and a 1251-labelled anti-mouse antibody. A calibration curve derived from a standard B19 IgM serum is used to quantify B19 IgM using a single dilution of test sera. The purpose of the protocol is the diagnosis of recent acute infection with parvovirus B19. 0 1997 Elsevier Science B.V. KeyM?or&: Parvovirus
B19; Antibody-capture;
Radioimmunoassay -.--
1. Type of research 1. Diagnosis
parvovirus B19 (Evans 4. Studies of nosocomial et al., 1984; Seng et al., 1994). 5. Evaluation of commercial parvovirus B19 IgM test kits (Cohen and Bates, 1995).
of parvovirus B19 infection (Cohen et al., 1983). 2. Identification of the clinical manifestations of parvovirus B19 infection (Anderson et al., 1984; Brown et al., 1984; White et al., 1985; Sergeant et al., 1993). 3. Surveillance of rash illness (Brown et al., 1994a). ___* Tel.: + 44 181 2004400; fax: + 44 181 2001569; e-mail:
protocol
[email protected]
dure
0166-0934/97:$17.00
2. Time required Time required for the whole protocol is approximately 30 h. The time for each step of the
Q 1997 Elsevier Science B.V. All rights reserved.
PII SO1 66-0934(97)00048-7
is estimated
(Section
4).
below
under
Detailed
proce-
2
B.J. Cohen /Journal
of Virological Methods 66 (1997) l-4
3. Materials
4. Detailed procedure
3.1. Special equipment
(1) Coat polystyrene beads in anti-human IgM. Immerse the required number of beads in anti-human IgM diluted to its optimal working dilution in coating buffer. Approximately 200 pi/bead of diluted anti-human IgM is required. Incubate with gentle agitation at room temperature for 2 h and then store at + 4°C until needed. (2) Prepare initial l/30 dilution of sera to be tested by adding 10 ~1 of serum to 290 ~1 of RIA diluent in 3 x 0.5 inch glass test tube. (3) Prepare final l/300 dilution of test sera by adding 20 ~1 of l/30 dilution to 180 ~1 of RIA diluent in well of reaction tray. (4) Prepare controls as follows: Make l/300 dilution of negative control by adding 15 ,ul NHS to 4.5ml RIA diluent. Make l/300 dilution of 100 B19 IgM RIA unit positive control by adding 3 ~1 100 unit control to 897 ~1 RIA diluent. Prepare a dilution series containing 33, 10, 3.3, 1 and 0.33 B19 IgM RIA units by dilution in RIA diluent containing l/300 dilution of NHS. (5) Dispense 200 ~1 of each control in duplicate wells (four wells for negative control). (6) Wash anti human IgM-coated beads three times with PBS. (7) Add one washed bead to each well, cover reaction tray with plate sealer and incubate for 2 h at 37°C. (8) Remove plate sealer and wash beads with PBST using ‘QuickWash’. (9) Add 200 ~1 B19 antigen (diluted in RIA diluent to its optimal working dilution) to each well and incubate for 3 h at 37°C. (10) Wash beads with PBST using ‘QuickWash’. (11) Add 200 ~1 of monoclonal antibody to B19 (diluted in RIA diluent plus 1% RS to its optimal working dilution) to each well and incubate overnight (about 16 h) at + 4°C. (12) Wash beads with PBST using ‘QuickWash’. (13) Add 200 ~1 of ‘251-anti mouse Ig, diluted in RIA diluent with 5% NHS and 5% RS to give approximately 80000 counts per min (cpm), to each well and incubate for 2 h at 37°C.
Gamma counter (NE 1600, Nuclear Enterprises, Edinburgh EHl 1 4BY, UK). Bead washing system (‘QuickWash’, Abbott Diagnostics Division, Irving, Laboratories, TX75038 USA). A 37°C waterbath or incubator. 3.2. Reagents Rabbit antibody to human IgM p chain specific (DAKO, High Wycombe, Bucks, HP13 5RE, UK). Native B19 antigen prepared from human plasma (Cohen et al., 1983). Mouse monoclonal antibody to parvovirus B19, e.g. VRL/B19-11 (Cohen et al., 1983). 1251-labelled sheep anti-mouse Ig (Amersham International, Little Chalfont, Bucks HP7 9NA, UK). A 0.05 M Carbonate bicarbonate buffer, pH 9.6 plus 0.08% sodium azide (coating buffer). Phosphate buffered saline (PBS). Tween - 20 (T20). Fetal calf serum (FCS). Rabbit serum (RS). Normal human serum (NHS), negative for B19 IgM, IgG and DNA. PBS plus 0.05% T20 (PBST). RIA diluent: PBST plus 10% FCS and 0.08% sodium azide. Human B19 IgM positive serum- 100 arbitrary RIA unit control. Etched polystyrene beads, surface enhanced, diameter 6.4 mm (NBL Gene Sciences, Northumberland NE23 9WF, UK). Reaction trays (Abbott Laboratories). A number of 3 x 0.5 inch glass test tubes for preparing serum dilutions. RIA counting tubes-75 x 12mm round base polystyrene test tube (Bibby Sterilin, Stone, Staffordshire ST15 OSA, UK). Self-adhesive plate sealers.
B.J. Cohen /Journal
of Virological Methods 66 (1997) l-4
(14) Wash beads with PPST using ‘QuickWash’. (15) Transfer beads to polystyrene counting tubes and count in gamma counter for 5 min.
5. Results The counts for each control sample (100 to 0.33 arbitrary RIA units) and test specimen (T) are divided by the mean count for the four replicates of the negative control (N) to give a T/N ratio. The T/N ratios of the control samples are plotted against arbitrary RIA units providing a calibration curve (Fig. 1). Using the calibration curve and T/N values a level of B19 IgM in terms of arbitrary RIA units is obtained for the test samples. A sample with < 1 unit is considered negative; > 3 positive and between 1 and 3 equivocal.
6. Discussion 6.1. Trouble shooting
The most common cause of problems is the use of a reagent (anti-human IgM, B19 antigen, monoclonal anti-B19 and lz51-anti mouse Ig) at suboptimal concentration. Each new batch of reagent must be titrated to ensure it is used at its optimal
30
20 TIN
concentration. In addition, different batches of the polystyrene bead solid phase may require re-optimisation of reagent concentration. The decay of the lz51 anti-mouse IgG reagent may present a problem- “‘1 has a half-life of 60 days. This can be compensated for, in part, by increasing the ‘dose’ (in terms of cpm) as the ‘*‘I antimouse IgG ages, though results are often optimal when this reagent is freshly-made. 6.2. Alternative and support controls Alternative protocols for B19 IgM exist which offer advantages to the MACRIA described here because of the use of non-radioactive conjugates as in ELISA and/or recombinant (non-infectious) B19 antigen as opposed to the native (infectious) B19 antigen. ELISA for B19 IgM was first described with native B19 antigen (Anderson et al., 1986) and subsequently with recombinant antigen produced using the baculovirus expression system (Salimans et al., 1992; O’Neil et al., 1995; Koch, 1995). B19 IgM ELISA kits based on baculovirus expressed antigen are now commercially available and their use for diagnostics has been evaluated (Cohen and Bates, 1995; Tolfvenstam et al., 1996: de Ory et al., 1996). MACRIA may also be performed with baculovirus expressed B19 antigen. However, the monoclonal antibody (VRL/B 19- 11) described for this protocol is not suitable as it recognises native B19 antigen only. Alternative monoclonal antibodies that do recognise recombinant B19 include 521-5D (Finkel et al., 1994) and R92F6 (O’Neil et al., 1995). Indeed, assay performance with this combination of reagents is enhanced and, in addition to the testing of sera, permits the detection of the low levels of B19-specific antibodies in oral fluids (Rice and Cohen, 1996).
7. Essential literature references B19 IgM RIA units
Fig. 1. Calibration curve for parvovirus B19 MACRIA. The B19 IgM level in test samples can be estimated from their T/N value by extrapolation of the arbitrary RIA units from the calibration curve.
3
Original papers: Cossart et al. (1975) Anderson et al. (1985). Book chapter: Young (1996). Review: Brown et al. (199413).
4
B.J. Cohen /Journal
of Virological Methods 66 (1997) l-4
References Anderson, M.J., Lewis, E., Kidd, I.M., Hall, SM., Cohen, B.J., 1984. An outbreak of erythema infectiosum associated with human parvovirus infection. J. Hyg. Camb. 93, 85593. Anderson, M.J., Higgins, P.G., Davis, L.R., Williamson, J.S., Jones, S.E., Kidd, I.M., Pattison, J.R., Tyrell, D.A.J., 1985. Experimental parvoviral infection in humans. J. Infect. Dis. 152, 2577265. Anderson, L.J., Tsou, C., Parker, R.A., Chorba, T.L., Wulff, H., Tattersall, P., Mortimer, P.P., 1986. Detection of antibodies and antigens of human parvovirus B19 by enzymelinked immunosorbent assay. J. Clin. Microbial. 24, 522-526. Brown, T., Anand, A., Ritchie, L.D., Clewley, J.P., Reid, T.M.S., 1984. Intrauterine parvovirus infection associated with hydrops fetalis. Lancet 2, 1033- 1034. Brown, D.W.G., Ramsay, M.E.B., Richards, A.F., Miller, E., 1994a. Salivary diagnosis of measles: a study of notified cases in the United Kingdom, 1991-1993. Br. Med. J. 308, 1015-1017. Brown, K.E., Young, N.S., Liu, J.M., 1994b. Molecular, cellular and clinical aspects of parvovirus B19 infection. Crit. Rev. Oncol. Hematol. 16, l-31. Cohen, B.J., Bates, CM., 1995. Evaluation of 4 commercial test kits for parvovirus B19 specific IgM. J. Virol. Methods 55, 11-25. Cohen, B.J., Mortimer, P.P., Pereira, M.S., 1983. Diagnostic assays with monoclonal antibodies for human serum parvovirus-like virus (SPLV). J. Hyg. Camb. 91, 113- 130. Cossart, Y.E., Cant, B., Field, A.M., Widdows, D., 1975. Parvovirus-like particles in human sera. Lancet 1, 72-73. Evans, J.P.M., Rossiter, M.A., Kumaran, T.O., Marsh, G.W., Mortimer, P.P., 1984. Human parvovirus aplasia: case due to cross infection in a ward. Br. Med. J. 288, 681. Finkel, T.H., T&ok, T.J., Ferguson, P.J., Durigon, E.L., Zaki, S.R., Leung, D.Y.M., Harbeck, R.J., Gelfand, E.W., Saulsbury, F.T., Hollister, J.R., Anderson, L.J., 1994.
Chronic parvovirus B19 infection and systemic necrotising vasculitis: opportunistic infection or aetiological agent?. Lancet 343, 125551258. Koch, W.C., 1995. A synthetic parvovirus B19 capsid protein can replace viral antigen in antibody-capture enzyme immunoassays. J. Virol. Methods 55, 67-82. O’Neil, H.J., Venugopal, K., Coyle, P.V., Gould, E.A., 1995. Development of an IgM capture assay for the diagnosis of B19 parvovirus infection using recombinant baculoviruses expressing VP1 or VP2 antigens. Clin. Diagn. Virol. 3, 181-190. de Ory, F., Guisacola, M.E., Ttllez, A., Domingo, C.T., 1996. Comparative evaluation of commercial methods for the detection of parvovirus B19-specific immunoglobulin M. Serodiagn. Immunother. Infect. Dis. 8, 117-120. Rice, P.S., Cohen, B.J., 1996. A school outbreak of parvovirus B19 infection investigated using salivary antibody assays. Epidemiol. Infect. 116, 331-338. Salimans, M.M.M., van Bussel, M.J.A.W.M., Brown, C.S., Spaan, W.J.M., 1992. Recombinant parvovirus B19 capsids as a new substrate for detection of B19-specific IgG and IgM antibodies by an enzyme-linked immunosorbent assay. J. Viral. Methods 39, 247-258. Seng, C., Watkins, P., Morse, D., Barrett, S.P., Zambon, M., Andrews, N., Atkins, M., Hall, S., Lau, Y.K., Cohen, B.J.. 1994. Parvovirus B19 outbreak on an adult ward. Epidemiol. Infect. 113, 3455353. Sergeant, G.R., Sergeant, B.E., Thomas, P.W., Anderson, M.J., Patou, G., Pattison, J.R., 1993. Human parvovirus infection in homozygous sickle cell disease. Lancet 341. 123771240. Tolfvenstam, T., Ruden, U., Broliden, K., 1996. Evaluation of serological assays for identification of parvovirus B19 immunoglobulin M. Clin. Diagn. Lab. Immunol. 3, 147- 150. White, D.G., Mortimer, P.P., Blake, D.R., Woolf, A.D., Cohen, B.J., Bacon, P.A., 1985. Human parvovirus arthropathy. Lancet 1, 419-421. Young, N.S., 1996. Parvoviruses. In: B.N. Fields, D.M. Knipe, P.M. Howley et al (Eds.), Fields Virology, LippincottRaven Press, Philadelphia, pp. 219992220.
ELSEVIER
Journal of Virological Methods 66 (1997) t-4
Protocol
Detection of parvovirus B 19-specific IgM by antibody capture radioimmunoassay Bernard
John Cohen ‘,*
aEnteric and Respiratory Virus Laboratory, Virus Rejtirence Division, Central Public Health Laboratory, Colindale Avenue, London NW9 5HT. UK
Abstract
A solid phase IgM-capture radioimmunoassay (MACRIA) for the detection of parvovirus B19-IgM is described (Cohen et al., 1983, J. Hyg. Camb. 91, 113-130). IgM from a dilution of patients serum is ‘captured’ onto a solid phase coated by anti-human IgM. To determine whether any of the IgM is specific for parvovirus B19, B19 antigen is added followed by a detector system. In the MACRIA described here the detector system comprises a mouse monoclonal antibody to parvovirus B19 and a 1251-labelled anti-mouse antibody. A calibration curve derived from a standard B19 IgM serum is used to quantify B19 IgM using a single dilution of test sera. The purpose of the protocol is the diagnosis of recent acute infection with parvovirus B19. 0 1997 Elsevier Science B.V. KeyM?or&: Parvovirus
B19; Antibody-capture;
Radioimmunoassay -.--
1. Type of research 1. Diagnosis
parvovirus B19 (Evans 4. Studies of nosocomial et al., 1984; Seng et al., 1994). 5. Evaluation of commercial parvovirus B19 IgM test kits (Cohen and Bates, 1995).
of parvovirus B19 infection (Cohen et al., 1983). 2. Identification of the clinical manifestations of parvovirus B19 infection (Anderson et al., 1984; Brown et al., 1984; White et al., 1985; Sergeant et al., 1993). 3. Surveillance of rash illness (Brown et al., 1994a). ___* Tel.: + 44 181 2004400; fax: + 44 181 2001569; e-mail:
protocol
[email protected]
dure
0166-0934/97:$17.00
2. Time required Time required for the whole protocol is approximately 30 h. The time for each step of the
Q 1997 Elsevier Science B.V. All rights reserved.
PII SO1 66-0934(97)00048-7
is estimated
(Section
4).
below
under
Detailed
proce-
2
B.J. Cohen /Journal
of Virological Methods 66 (1997) l-4
3. Materials
4. Detailed procedure
3.1. Special equipment
(1) Coat polystyrene beads in anti-human IgM. Immerse the required number of beads in anti-human IgM diluted to its optimal working dilution in coating buffer. Approximately 200 pi/bead of diluted anti-human IgM is required. Incubate with gentle agitation at room temperature for 2 h and then store at + 4°C until needed. (2) Prepare initial l/30 dilution of sera to be tested by adding 10 ~1 of serum to 290 ~1 of RIA diluent in 3 x 0.5 inch glass test tube. (3) Prepare final l/300 dilution of test sera by adding 20 ~1 of l/30 dilution to 180 ~1 of RIA diluent in well of reaction tray. (4) Prepare controls as follows: Make l/300 dilution of negative control by adding 15 ,ul NHS to 4.5ml RIA diluent. Make l/300 dilution of 100 B19 IgM RIA unit positive control by adding 3 ~1 100 unit control to 897 ~1 RIA diluent. Prepare a dilution series containing 33, 10, 3.3, 1 and 0.33 B19 IgM RIA units by dilution in RIA diluent containing l/300 dilution of NHS. (5) Dispense 200 ~1 of each control in duplicate wells (four wells for negative control). (6) Wash anti human IgM-coated beads three times with PBS. (7) Add one washed bead to each well, cover reaction tray with plate sealer and incubate for 2 h at 37°C. (8) Remove plate sealer and wash beads with PBST using ‘QuickWash’. (9) Add 200 ~1 B19 antigen (diluted in RIA diluent to its optimal working dilution) to each well and incubate for 3 h at 37°C. (10) Wash beads with PBST using ‘QuickWash’. (11) Add 200 ~1 of monoclonal antibody to B19 (diluted in RIA diluent plus 1% RS to its optimal working dilution) to each well and incubate overnight (about 16 h) at + 4°C. (12) Wash beads with PBST using ‘QuickWash’. (13) Add 200 ~1 of ‘251-anti mouse Ig, diluted in RIA diluent with 5% NHS and 5% RS to give approximately 80000 counts per min (cpm), to each well and incubate for 2 h at 37°C.
Gamma counter (NE 1600, Nuclear Enterprises, Edinburgh EHl 1 4BY, UK). Bead washing system (‘QuickWash’, Abbott Diagnostics Division, Irving, Laboratories, TX75038 USA). A 37°C waterbath or incubator. 3.2. Reagents Rabbit antibody to human IgM p chain specific (DAKO, High Wycombe, Bucks, HP13 5RE, UK). Native B19 antigen prepared from human plasma (Cohen et al., 1983). Mouse monoclonal antibody to parvovirus B19, e.g. VRL/B19-11 (Cohen et al., 1983). 1251-labelled sheep anti-mouse Ig (Amersham International, Little Chalfont, Bucks HP7 9NA, UK). A 0.05 M Carbonate bicarbonate buffer, pH 9.6 plus 0.08% sodium azide (coating buffer). Phosphate buffered saline (PBS). Tween - 20 (T20). Fetal calf serum (FCS). Rabbit serum (RS). Normal human serum (NHS), negative for B19 IgM, IgG and DNA. PBS plus 0.05% T20 (PBST). RIA diluent: PBST plus 10% FCS and 0.08% sodium azide. Human B19 IgM positive serum- 100 arbitrary RIA unit control. Etched polystyrene beads, surface enhanced, diameter 6.4 mm (NBL Gene Sciences, Northumberland NE23 9WF, UK). Reaction trays (Abbott Laboratories). A number of 3 x 0.5 inch glass test tubes for preparing serum dilutions. RIA counting tubes-75 x 12mm round base polystyrene test tube (Bibby Sterilin, Stone, Staffordshire ST15 OSA, UK). Self-adhesive plate sealers.
B.J. Cohen /Journal
of Virological Methods 66 (1997) l-4
(14) Wash beads with PPST using ‘QuickWash’. (15) Transfer beads to polystyrene counting tubes and count in gamma counter for 5 min.
5. Results The counts for each control sample (100 to 0.33 arbitrary RIA units) and test specimen (T) are divided by the mean count for the four replicates of the negative control (N) to give a T/N ratio. The T/N ratios of the control samples are plotted against arbitrary RIA units providing a calibration curve (Fig. 1). Using the calibration curve and T/N values a level of B19 IgM in terms of arbitrary RIA units is obtained for the test samples. A sample with < 1 unit is considered negative; > 3 positive and between 1 and 3 equivocal.
6. Discussion 6.1. Trouble shooting
The most common cause of problems is the use of a reagent (anti-human IgM, B19 antigen, monoclonal anti-B19 and lz51-anti mouse Ig) at suboptimal concentration. Each new batch of reagent must be titrated to ensure it is used at its optimal
30
20 TIN
concentration. In addition, different batches of the polystyrene bead solid phase may require re-optimisation of reagent concentration. The decay of the lz51 anti-mouse IgG reagent may present a problem- “‘1 has a half-life of 60 days. This can be compensated for, in part, by increasing the ‘dose’ (in terms of cpm) as the ‘*‘I antimouse IgG ages, though results are often optimal when this reagent is freshly-made. 6.2. Alternative and support controls Alternative protocols for B19 IgM exist which offer advantages to the MACRIA described here because of the use of non-radioactive conjugates as in ELISA and/or recombinant (non-infectious) B19 antigen as opposed to the native (infectious) B19 antigen. ELISA for B19 IgM was first described with native B19 antigen (Anderson et al., 1986) and subsequently with recombinant antigen produced using the baculovirus expression system (Salimans et al., 1992; O’Neil et al., 1995; Koch, 1995). B19 IgM ELISA kits based on baculovirus expressed antigen are now commercially available and their use for diagnostics has been evaluated (Cohen and Bates, 1995; Tolfvenstam et al., 1996: de Ory et al., 1996). MACRIA may also be performed with baculovirus expressed B19 antigen. However, the monoclonal antibody (VRL/B 19- 11) described for this protocol is not suitable as it recognises native B19 antigen only. Alternative monoclonal antibodies that do recognise recombinant B19 include 521-5D (Finkel et al., 1994) and R92F6 (O’Neil et al., 1995). Indeed, assay performance with this combination of reagents is enhanced and, in addition to the testing of sera, permits the detection of the low levels of B19-specific antibodies in oral fluids (Rice and Cohen, 1996).
7. Essential literature references B19 IgM RIA units
Fig. 1. Calibration curve for parvovirus B19 MACRIA. The B19 IgM level in test samples can be estimated from their T/N value by extrapolation of the arbitrary RIA units from the calibration curve.
3
Original papers: Cossart et al. (1975) Anderson et al. (1985). Book chapter: Young (1996). Review: Brown et al. (199413).
4
B.J. Cohen /Journal
of Virological Methods 66 (1997) l-4
References Anderson, M.J., Lewis, E., Kidd, I.M., Hall, SM., Cohen, B.J., 1984. An outbreak of erythema infectiosum associated with human parvovirus infection. J. Hyg. Camb. 93, 85593. Anderson, M.J., Higgins, P.G., Davis, L.R., Williamson, J.S., Jones, S.E., Kidd, I.M., Pattison, J.R., Tyrell, D.A.J., 1985. Experimental parvoviral infection in humans. J. Infect. Dis. 152, 2577265. Anderson, L.J., Tsou, C., Parker, R.A., Chorba, T.L., Wulff, H., Tattersall, P., Mortimer, P.P., 1986. Detection of antibodies and antigens of human parvovirus B19 by enzymelinked immunosorbent assay. J. Clin. Microbial. 24, 522-526. Brown, T., Anand, A., Ritchie, L.D., Clewley, J.P., Reid, T.M.S., 1984. Intrauterine parvovirus infection associated with hydrops fetalis. Lancet 2, 1033- 1034. Brown, D.W.G., Ramsay, M.E.B., Richards, A.F., Miller, E., 1994a. Salivary diagnosis of measles: a study of notified cases in the United Kingdom, 1991-1993. Br. Med. J. 308, 1015-1017. Brown, K.E., Young, N.S., Liu, J.M., 1994b. Molecular, cellular and clinical aspects of parvovirus B19 infection. Crit. Rev. Oncol. Hematol. 16, l-31. Cohen, B.J., Bates, CM., 1995. Evaluation of 4 commercial test kits for parvovirus B19 specific IgM. J. Virol. Methods 55, 11-25. Cohen, B.J., Mortimer, P.P., Pereira, M.S., 1983. Diagnostic assays with monoclonal antibodies for human serum parvovirus-like virus (SPLV). J. Hyg. Camb. 91, 113- 130. Cossart, Y.E., Cant, B., Field, A.M., Widdows, D., 1975. Parvovirus-like particles in human sera. Lancet 1, 72-73. Evans, J.P.M., Rossiter, M.A., Kumaran, T.O., Marsh, G.W., Mortimer, P.P., 1984. Human parvovirus aplasia: case due to cross infection in a ward. Br. Med. J. 288, 681. Finkel, T.H., T&ok, T.J., Ferguson, P.J., Durigon, E.L., Zaki, S.R., Leung, D.Y.M., Harbeck, R.J., Gelfand, E.W., Saulsbury, F.T., Hollister, J.R., Anderson, L.J., 1994.
Chronic parvovirus B19 infection and systemic necrotising vasculitis: opportunistic infection or aetiological agent?. Lancet 343, 125551258. Koch, W.C., 1995. A synthetic parvovirus B19 capsid protein can replace viral antigen in antibody-capture enzyme immunoassays. J. Virol. Methods 55, 67-82. O’Neil, H.J., Venugopal, K., Coyle, P.V., Gould, E.A., 1995. Development of an IgM capture assay for the diagnosis of B19 parvovirus infection using recombinant baculoviruses expressing VP1 or VP2 antigens. Clin. Diagn. Virol. 3, 181-190. de Ory, F., Guisacola, M.E., Ttllez, A., Domingo, C.T., 1996. Comparative evaluation of commercial methods for the detection of parvovirus B19-specific immunoglobulin M. Serodiagn. Immunother. Infect. Dis. 8, 117-120. Rice, P.S., Cohen, B.J., 1996. A school outbreak of parvovirus B19 infection investigated using salivary antibody assays. Epidemiol. Infect. 116, 331-338. Salimans, M.M.M., van Bussel, M.J.A.W.M., Brown, C.S., Spaan, W.J.M., 1992. Recombinant parvovirus B19 capsids as a new substrate for detection of B19-specific IgG and IgM antibodies by an enzyme-linked immunosorbent assay. J. Viral. Methods 39, 247-258. Seng, C., Watkins, P., Morse, D., Barrett, S.P., Zambon, M., Andrews, N., Atkins, M., Hall, S., Lau, Y.K., Cohen, B.J.. 1994. Parvovirus B19 outbreak on an adult ward. Epidemiol. Infect. 113, 3455353. Sergeant, G.R., Sergeant, B.E., Thomas, P.W., Anderson, M.J., Patou, G., Pattison, J.R., 1993. Human parvovirus infection in homozygous sickle cell disease. Lancet 341. 123771240. Tolfvenstam, T., Ruden, U., Broliden, K., 1996. Evaluation of serological assays for identification of parvovirus B19 immunoglobulin M. Clin. Diagn. Lab. Immunol. 3, 147- 150. White, D.G., Mortimer, P.P., Blake, D.R., Woolf, A.D., Cohen, B.J., Bacon, P.A., 1985. Human parvovirus arthropathy. Lancet 1, 419-421. Young, N.S., 1996. Parvoviruses. In: B.N. Fields, D.M. Knipe, P.M. Howley et al (Eds.), Fields Virology, LippincottRaven Press, Philadelphia, pp. 219992220.