Identification of indigenous hepatitis E virus from a Japanese patient who contracted sporadic acute hepatitis in 1982.

Figure 1. Phylogenetic tree constructed by the neighbor-joining method and based on the partial nucleotide sequence (301 nt) of the open reading frame 2 region of 50 human and swine hepatitis E virus (HEV) isolates. The nucleotide sequences of 49 known human and swine HEV isolates were retrieved from GenBank/DDBJ/EMBL databases on 22 July 2002. The partial nucleotide sequence of HE-JO-1982 obtained in the present study is deposited under accession no. AB088418 and is boxed for visual clarity. All human and swine HEV strains of Japanese origin are indicated by boldface type. Bootstrap values 170% are indicated for the major nodes as a percentage of the data obtained from 1000 resamplings [9]. To the Editor—We read with great interest the article by Taka-hashi et al. [1], who recovered 7 hepatitis E virus (HEV) isolates of genotype I, III, and IV from Japanese patients with sporadic acute hepatitis who were treated during 1996–2001 and showed the wide genetic diversity of HEV in Japan. On the basis of the existence of pairs of highly homologous isolates, Takahashi and colleagues speculated that multiple HEV strains have already made inroads and are spreading in Japan. HEV is a major cause of outbreaks and sporadic cases of viral hepatitis in tropical and subtropical countries [2]. There is growing consensus that sporadic hepatitis E disease occurs in individuals in industrialized countries who have no epidemiologic evidence of exposure to HEV strains from countries where the disease is endemic and that HEV is a zoonotic virus, as suggested by the close genetic relationship between swine and human viruses [2–4]. HEV variants of genotypes III and IV have been isolated from sporadic cases of acute hepatitis in the United States, Europe, China, Taiwan, and Japan [2–6]; however, when such variants emerged in these industrialized countries remains unknown. The findings of Takahashi et al. [1] led us to analyze stored serum samples from a 38-year-old man who came to our hospital in January 1982 for treatment of jaundice and general fatigue. The serum samples were obtained on hospital admission, and the patient was given a clinical diagnosis of sporadic acute hepatitis of non-A, non-B etiology at that time. The serum samples were tested for IgM and IgG antibodies to HEV (anti-HEV) by in-house EIA, using purified recombinant open-reading frame 2 (ORF2) protein, which had been expressed in silkworm pupae, as the antigen probe. The serum samples were also tested …