Erythrocyte binding preference of human pandemic infuenza virus A and its effect on antibody response detection

Abstract

Background: Validation of hemagglutination inhibition (HI) assays is important for evaluating antibody responses to infuenza virus, and selection of erythrocytes for use in these assays is important. This study aimed to determine the correlation between receptor binding specifcity and effectiveness of the HI assay for detecting antibody response to pandemic infuenza H1N1 (pH1N1) virus. Methods: Hemagglutination (HA) tests were performed using erythrocytes from 6 species. Subsequently, 8 hemagglutinating units of pH1N1 from each species were titrated by realtime reverse transcription-PCR. To investigate the effect of erythrocyte binding preference on HI antibody titers, comparisons of HI with microneutralization (MN) assays were performed. Results: Goose erythrocytes showed most specifc binding with pH1N1, while HA titers using human erythrocytes were comparable to those using turkey erythrocytes. The erythrocyte binding effciency was shown to have an impact on antibody detection. Comparing MN titers, HI titers using turkey erythrocytes yielded the most accurate results, while those using goose erythrocytes produced the highest geometric mean titer. Human blood group O erythrocytes lacking a specifc antibody yielded results most comparable to those obtained using turkey erythrocytes. Further, pre-existing antibody to pH1N1 and different erythrocyte species can distort HI assay results. Conclusions: HI assay, using turkey and human erythrocytes, yielded the most comparable and applicable results for pH1N1 than those by MN assay, and using goose erythrocytes may lead to overestimated titers. Selection of appropriate erythrocyte species for HI assay allows construction of a more reliable database, which is essential for further investigations and control of virus epidemics. © The Korean Society for Laboratory Medicine.