Redeveloping antigen detection kits for the diagnosis of rat hepatitis E virus

Abstract

The emergence of <i>Rocahepevirus ratti</i> [species HEV <i>ratti</i> (<i>r</i> HEV)] as a causative agent of hepatitis E in humans presents a new potential threat to global public health. The <i>R. ratti</i> genotype 1 (<i>r</i>-1 HEV) variant only shares 50%-60% genomic identity with <i>Paslahepevirus balayani</i> [species HEV <i>balayani</i> (<i>b</i> HEV)] variants, which are the main causes of hepatitis E infection in humans. Here, we report antigen diagnoses for <i>r</i>-1 HEV and <i>b</i> HEV using an enzymatic immunoassay (EIA) method. We detected recombinant virus-like particles protein (HEV 239) of <i>r</i> HEV and <i>b</i> HEV using a collection of hepatitis E virus (HEV)-specific monoclonal antibodies. Two optimal candidates, the capture antibody P#1-H4 and the detection antibodies C145 (P#1-H4*/C145^#) and C158 (P#1-H4*/C158^#), were selected to detect antigen in infected rat samples and <i>r</i>-1 HEV- or <i>b</i> HEV-infected human clinical samples. The two candidates showed similar diagnostic efficacy to the Wantai HEV antigen kit in <i>b</i> HEV-infected clinical samples. Genomic divergence resulted in low diagnostic efficacy of the Wantai HEV antigen kit (0%, 0 of 10) for detecting <i>r</i>-1 HEV infection. Compared with the P#1-H4*/C145^# candidate (80%, 8 of 10), the P#1-H4*/C158^# candidate had excellent diagnostic efficacy in <i>r</i>-1 HEV-infected clinical samples (100%, 10 of 10). The two candidates bind to a discrete antigenic site that is highly conserved across <i>r</i> HEV and <i>b</i> HEV. P#1-H4*/C145^# and P#1-H4*/C158^# are efficacious candidate antibody combinations for rat HEV antigen detection.