Generation of hepatitis E virus-like particles of two new genotypes G5 and G6 and comparison of antigenic properties with those of known genotypes

- Native size and small VLPs of G5 and G6 HEV were produced by a recombinant baculovirus system.
- G5 and G6 VLPs showed stronger antigenic cross-reactivity against G1, G3 and G4 HEV vs. ferret or rat HEV.
- The G5 and G6 HEVs have the same serotype as human HEVs.

In addition to the four major genotypes (G1 through G4) known for human hepatitis E virus (HEV), two new genotypes (G5 and G6) were suggested, based on unique viral nucleotide sequences derived from wild boars in Japan. It has been unknown whether the virus of these new genotypes can cause hepatitis in humans; neither G5 nor G6 HEV has been found in patients to date. To study the antigenic properties of G5 and G6 HEV, we expressed N-terminus-truncated HEV ORF2 protein by a recombinant baculovirus system, and we obtained virus-like particles (VLPs) for both G5 and G6. The VLPs showed antigenic cross-reactivity against G1, G3 and G4 HEV more strongly than against ferret or rat HEV. Moreover, both anti-G5 and anti-G6 VLPs antibodies could neutralize G3 HEV's ability to infect PLC/PRF/5 cells, suggesting that G5 and G6 HEV have the same serotype as human HEV.