Full‐genome characterization of the RIVM‐HAV16‐090‐like hepatitis A virus strains recovered from Japanese men who have sex with men, with sporadic acute hepatitis A

Aim The major transmission mode of hepatitis A virus (HAV) in Japan is the fecal–oral route by contaminated foods. In contrast, HAV infection is well documented as a sexually transmitted disease in Europe and North America. The present study was undertaken to determine the full‐genome sequence of HAV and trace the transmission route of HAV in Japanese men who have sex with men (MSM). Methods In 2018, we encountered three Japanese MSM with acute hepatitis A co‐infected with HIV for 4–12 years. Serum samples obtained from these patients were used for HAV full‐genome analyses. Results Isolated HAV strains were segregated into subgenotype IA. The three HAV strains shared 100% identity within the 481‐nucleotide partial sequence. The entire nucleotide sequence showed that the three strains were 99.97% similar to each other with only two nucleotide substitutions. At the amino acid level, the three strains differed from each other by only one or two amino acids. All three strains obtained in the present study were >99.6% identical to the 66 reported strains isolated from Taiwan and European countries during 2015–2017. In addition, these 66 strains include the RIVM‐HAV16‐090 (EuroPride) strain, which has been involved in HAV outbreaks among MSM worldwide. Conclusions We determined for the first time the full‐genome sequence of HAV isolated from Japanese MSM with acute hepatitis A and found that the strains were identical to those from MSM worldwide. Thus, these HAV strains were imported to Japan from foreign countries through MSM.