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

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