Hepatitis E virus (HEV) is the aetiological agent of enterically transmitted
hepatitis. The traditional methods for evaluating
neutralizing antibody titres against HEV are real-time PCR and the immunofluorescence foci assay (IFA), which are poorly repeatable and operationally complicated, factors that limit their applicability to high-throughput assays. In this study, we developed a novel high-throughput neutralizing assay based on
biotin-conjugated p239 (HEV recombinant
capsid proteins, a.a. 368-606) and staining with
allophycocyanin-conjugated
streptavidin (
streptavidin APC) to amplify the fluorescence signal. A linear regression analysis indicated that there was a high degree of correlation between IFA and the novel assay. Using this method, we quantitatively evaluated the neutralization of sera from HEV-infected and vaccinated macaques. The anti-HEV
IgG level had good concordance with the neutralizing titres of macaque sera. However, the neutralization titres of the sera were also influenced by anti-HEV
IgM responses. Further analysis also indicated that, although vaccination with HEV
vaccine stimulated higher anti-HEV
IgG and neutralization titres than
infection with HEV in macaques, the proportions of
neutralizing antibodies in the infected macaques' sera were higher than in the vaccinated macaques with the same anti-HEV
IgG levels. Thus, the
infection more efficiently stimulated
neutralizing antibody responses.