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Journal of Virology, September 2000, p. 8011-8017, Vol. 74, No. 17
Hepatitis Research Unit and Australian Centre
for Hepatitis Virology, Macfarlane Burnet Centre for Medical
Research, Fairfield 3078, Victoria, Australia
Received 28 December 1999/Accepted 30 May 2000
Antibody to the capsid (PORF2) protein of hepatitis E virus (HEV)
is sufficient to confer immunity, but knowledge of B-cell epitopes in
the intact capsid is limited. A panel of murine monoclonal antibodies
(MAbs) was generated following immunization with recombinant ORF2.1
protein, representing the C-terminal 267 amino acids (aa) of the 660-aa
capsid protein. Two MAbs reacted exclusively with the conformational
ORF2.1 epitope (F. Li, J. Torresi, S. A. Locarnini, H. Zhuang, W. Zhu, X. Guo, and D. A. Anderson, J. Med. Virol. 52:289-300,
1997), while the remaining five demonstrated reactivity with epitopes
in the regions aa 394 to 414, 414 to 434, and 434 to 457. The antigenic
structures of both the ORF2.1 protein expressed in Escherichia
coli and the virus-like particles (VLPs) expressed using the
baculovirus system were examined by competitive enzyme-linked immunosorbent assays (ELISAs) using five of these MAbs and HEV patient
sera. Despite the wide separation of epitopes within the primary
sequence, all the MAbs demonstrated some degree of cross-inhibition with each other in ORF2.1 and/or VLP ELISAs, suggesting a complex antigenic structure. MAbs specific for the conformational ORF2.1 epitope and a linear epitope within aa 434 to 457 blocked convalescent patient antibody reactivity against VLPs by approximately 60 and 35%,
respectively, while MAbs against epitopes within aa 394 to 414 and 414 to 434 were unable to block patient serum reactivity. These results
suggest that sequences spanning aa 394 to 457 of the capsid protein
participate in the formation of strongly immunodominant epitopes on the
surface of HEV particles which may be important in immunity to HEV infection.
0022-538X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Identification of Immunodominant and Conformational
Epitopes in the Capsid Protein of Hepatitis E Virus by Using
Monoclonal Antibodies

*
Corresponding author. Mailing address: Hepatitis
Research Unit, Macfarlane Burnet Centre for Medical Research. P.O. Box
254, Fairfield 3078, Melbourne, Victoria, Australia. Phone: (61 3) 9282 2239. Fax: (61 3) 9282 2100. E-mail:
anderson{at}burnet.edu.au.
Present address: Victorian Infectious Diseases Reference
Laboratory, North Melbourne 3051, Australia.
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