Detection and isolation of genotype 3 subtype b hepatitis E viruses from wild boars in Japan

To conduct an epidemiological study of hepatitis E virus (HEV) in Japanese wild boars, we collected 179 serum and 162 fecal specimens from wild boars in eight Japanese prefectures; 39 of the serum samples (21.8%) were positive for anti-HEV IgG antibodies. RT-qPCR revealed HEV RNA in 11 serum samples (6.1%) and 5 fecal samples (3.1%). We obtained 412 bp of the viral genome sequences of ORF2 from five pairs of serum and fecal samples. All strains were subtype b in genotype 3 (HEV-3b) but separated into different clusters. We determined the entire genome sequence of HEV-3b strain WB0567 using a fecal specimen and isolated this strain by cell culture using PLC/PRF/5 cells. Eleven nucleotide mutations had occurred during virus replication. These results suggest that HEV-3b circulated uniformly among wild boars in Japan. Direct sequencing using a suspected animal's samples is indispensable for predicting original HEV nucleotide sequences.