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, and its prevalence differed by geographic region (6 to 25%), with a higher rate in the northern part of Japan. At admission, the 11 patients with HEV-associated hepatitis had elevated alanine aminotransferase levels of 914 to 4,850 IU/liter, and all but 1 had elevated bilirubin levels of 1.5 to 24.0 mg/dl. The 11 HEV isolates were of genotype III or IV and were segregated into three groups with intergroup nucleotide differences of 9.5 to 22.0%. Phylogenetic analysis revealed that four isolates of genotype III were closely related to a Japanese isolate, while the other four isolates of the same genotype were nearest those from the United States. The remaining three isolates were close to known isolates of genotype IV in China and Taiwan but shared less than 88% identity with them. These results indicate that multiple genotypes of HEV cocirculate in Japan and contribute to the development of sporadic acute hepatitis, with the prevalence differing by age, sex, and geographic region.

Japanese patients with sporadic acute hepatitis E are infected with polyphyletic strains of hepatitis E virus (HEV). Hepatitis E is considered a zoonotic disease. Thus far in Japan, only three strains of swine HEV have been identified and an antibody study for HEV antibodies has not been done on Japanese pigs. To determine the prevalence of swine HEV infection in Japan and the extent of genetic variation among Japanese swine HEV strains, we tested serum samples obtained from 2500 pigs from 2 to 6 months of age at 25 commercial swine farms in Japan for the presence of IgG antibodies to HEV and swine HEV RNA. Anti-HEV antibodies were detected in 1448 pigs (58 %). One-hundred-and-thirteen (15 %) of the 750 3-month-old pigs and 24 (13 %) of the 180 4-monthold pigs were positive for swine HEV RNA. The nucleotide sequence of a 412 bp region within open reading frame 2 of the 137 swine HEV isolates was determined. Sequence analyses revealed that the 137 isolates shared 76?6-100 % nucleotide sequence identities and were classifiable into genotype III (93 %) or IV (7 %) and that the isolates from the same farm were ¢97?1 % similar to each other. Phylogenetic analysis showed that the Japanese swine and human HEV isolates segregated into four clusters, with the highest nucleotide identity being 94?4-100 % between swine and human isolates in each cluster. These results indicate that swine HEV is widespread in the Japanese swine population and further support the hypothesis that swine serve as reservoirs for HEV infection. INTRODUCTIONHepatitis E virus (HEV) is an unclassified virus that is the major causative pathogen of enterically transmitted non-A, non-B hepatitis in many developing countries in Asia, Africa and Latin America (Purcell & Emerson, 2001a). There is a growing consensus that HEV-associated hepatitis also occurs among individuals in industrialized nations who have no history of travel to areas endemic for HEV (Harrison, 1999;Purcell & Emerson, 2001a;Schlauder & Mushahwar, 2001).The genome of HEV is a single-stranded, positive-sense RNA of approximately 7?2 kb and contains a short 59 untranslated region (59UTR), three open reading frames (ORF1, ORF2 and ORF3) and a short 39UTR terminated by a poly(A) tract (Reyes et al., 1990;Tam et al., 1991). HEV sequences have tentatively been classified into four major genetic groups (genotypes I-IV) (Schlauder & Mushahwar, 2001). The majority of HEV infections in several countries in Asia and Africa are caused by genotype I and the majority of HEV infections in Mexico and Nigeria are caused by genotype II, while only isolated cases of infection with HEV of genotype III or IV have been described in the US, European countries, Argentina, Taiwan and China (Hsieh et al., 1999;Pina et al., 2000;Schlauder et al., 1998Schlauder et al., , 1999Schlauder et al., , 2000Wang et al., 1999Wang et al., , 2000Wang et al., , 2001Worm et al., 2000;Zanetti et al., 1999). In Japan, 13 % (11/87) of the cases of acute non-A, non-B, non-C hepatitis were caused by HEV infection (Mizuo et al., 20...

The prevalence of infection with hepatitis A virus (HAV), HBV, HCV, HDV, and HEV was evaluated in 249 apparently healthy individuals, including 122 inhabitants in Ulaanbaatar, the capital city of Mongolia, and 127 age-and sex-matched members of nomadic tribes who lived around the capital city. Overall, hepatitis B surface antigen (HBsAg) was detected in 24 subjects (10%), of whom 22 (92%) had detectable HBV DNA. Surprisingly, HDV RNA was detectable in 20 (83%) of the 24 HBsAg-positive subjects. HCV-associated antibodies were detected in 41 (16%) and HCV RNA was detected in 36 (14%) subjects, none of whom was coinfected with HBV, indicating that HBV/HCV carriers account for one-fourth of this population. Antibodies to HAV and HEV were detected in 249 (100%) and 28 (11%) subjects, respectively. Of 22 HBV DNA-positive subjects, genotype D was detected in 21 subjects and genotype F was detected in 1 subject. All 20 HDV isolates recovered from HDV RNA-positive subjects segregated into genotype I, but these differed by 2.1 to 11.4% from each other in the 522-to 526-nucleotide sequence. Of 36 HCV RNA-positive samples, 35 (97%) were genotype 1b and 1 was genotype 2a. Reflecting an extremely high prevalence of hepatitis virus infections, there were no appreciable differences in the prevalence of hepatitis virus markers between the two studied populations with distinct living place and lifestyle. A nationwide epidemiological survey of hepatitis viruses should be conducted in an effort to prevent de novo infection with hepatitis viruses in Mongolia.

The full-length genomic sequences were determined of Japanese swine and human hepatitis E virus (HEV) isolates (swJ13-1 and HE-JA1, respectively) with 100 % identity in the partial sequence of open reading frame (ORF) 2 (ORF2, 412 nt). swJ13-1 was isolated from a 4-month-old farm pig born in Hokkaido, Japan, in 2002 and HE-JA1 was recovered from a 55-year-old patient who lived in Hokkaido and who had contracted sporadic acute hepatitis E in 1997. Both isolates consisted of 7240 nt, excluding the poly(A) tail, and contained three ORFs (ORFs 1-3) that encoded proteins of 1707, 674 and 114 aa. The overall nucleotide sequence identity between them was 99?0 % and the deduced amino acid sequence identities of ORFs 1-3 were 99?8, 100 and 100 %, respectively. The high degree of genomic similarity observed between swine and human HEV isolates in a restricted area of Japan further supports the finding that sporadic hepatitis E in Japan is a zoonosis.Hepatitis E virus (HEV), the causative agent of hepatitis E, is a single-stranded, positive-sense, naked RNA virus (Purcell & Emerson, 2001a). Hepatitis E is an important public concern in many developing countries in Asia, Africa and Latin America, wherein both epidemic and sporadic forms exist (Purcell & Emerson, 2001a). Recent studies have documented that HEV-associated hepatitis also occurs among individuals in industrialized countries with no history of travel to areas endemic for HEV (Harrison, 1999;Purcell & Emerson, 2001a;Schlauder & Mushahwar, 2001;Smith, 2001) and that HEV is a potential zoonotic virus, as suggested by the close genetic relationship between human and swine viruses (Erker et al., 1999; Hsieh et al., 1999;Meng et al., 1997;Pina et al., 2000;Wu et al., 2002) and experimental cross-species infection of swine HEV to a chimpanzee and rhesus monkeys (Meng et al., 1998). The genome of HEV is approximately 7?2 kb long and contains a short 59 untranslated region (UTR), three open reading frames (ORFs 1-3) and a short 39 UTR terminated by a poly(A) tract (Reyes et al., 1990;Tam et al., 1991). Based on sequence analyses, the HEV isolates identified worldwide have been classified tentatively into four major genotypes (Schlauder & Mushahwar, 2001). These include genotypes I (HEV isolates from several countries in Asia and Africa), II (HEV isolates from Mexico and Nigeria), III (HEV isolates from the United States, European countries and Argentina) and IV (HEV isolates from China and Taiwan) (Hsieh et al., 1999;Pina et al., 2000;Schlauder et al., 1998Schlauder et al., , 1999Schlauder et al., , 2000Wang et al., 1999Wang et al., , 2000Wang et al., , 2001aWorm et al., 2000;Zanetti et al., 1999). In Japan, multiple HEV strains of genotype III or IV have been isolated from patients with sporadic acute or fulminant hepatitis of non-A, non-B, non-C aetiology who had not travelled abroad Mizuo et al., 2002;Suzuki et al., 2002;Takahashi et al., 2001Takahashi et al., , 2002a and from farm pigs (Okamoto et al., 2001;Takahashi et al., 2003). In our previous study, we identifie...

HBV NAT screening detected HBV DNA in both early (the so-called serological window period) and late stages of acute HBV infection.

Ongoing subclinical infection of hepatitis E virus (HEV) has not been fully studied. In the present study, serum samples were collected from 6700 voluntary blood donors with an elevated alanine aminotransferase (ALT) level of 61-476 IU/l at a Japanese Red Cross Blood Center, and were tested for the presence of IgG, IgM and IgA classes of antibodies to HEV (anti-HEV) by in-house ELISA and HEV RNA by nested RT-PCR. Overall, 479 blood donors (7.1%) were positive for anti-HEV IgG, including 8 donors with anti-HEV IgM and 7 donors with anti-HEV IgA. Among the nine donors with anti-HEV IgM and/or anti-HEV IgA, six had detectable HEV RNA. The presence of HEV RNA was further tested in 10-sample minipools of sera from the remaining 6691 donors, and three donors including one without anti-HEV IgG were found to be positive for HEV RNA. When stratified by ALT level, the prevalence of HEV RNA was significantly higher among the 109 donors with ALT > or = 201 IU/l than among the 6591 donors with ALT of 61-200 IU/l (2.8% vs. 0.1%, P < 0.0001). The HEV isolates obtained from the nine viremic donors segregated into genotype 3, shared a wide range of identities of 85.6-98.5% and were 87.3-93.9% similar to the Japan-indigenous HEV strain (JRA1), in the 412-nucleotide sequence of open reading frame 2. This study suggests that approximately 3% of Japanese individuals with ALT > or = 201 IU/l have ongoing subclinical infection with various HEV strains.

One hundred fifty-four consecutive patients with sporadic acute hepatitis, who were seen at a city hospital in the Kathmandu valley of Nepal in 1997, were studied. IgM antibodies to hepatitis A virus were detected in four patients (3%), IgM antibodies to hepatitis B core in four patients (3%), hepatitis B surface antigen in 20 (13%), and hepatitis C virus RNA in four patients (3%). IgM antibodies to hepatitis E virus (HEV) (anti-HEV IgM) and HEV RNA were detected in 77 (50%) and 48 (31%), respectively. Consequently, 86 patients (56%) including nine HEV-viremic patients without anti-HEV IgM, were diagnosed with hepatitis E. The cause of hepatitis was not known in 53 patients (34%). All 48 HEV RNA-positive samples were genotyped as 1, and subtyped further as 1a in 17 (35%), 1c in 29 (60%), and mixed infection of 1a and 1c in 2 (4%). A seasonal difference in the prevalence of HEV subtypes was recognized. Before the rainy season (January to July), both 1a and 1c isolates were found: the intrasubtypic difference was up to 9.0% and 1.7%, respectively, in the 412-nucleotide sequence of open reading frame 2. During the rainy season (August), only 1c isolates (n = 17) with 99.5-100% identity were found; 13 of 17 isolates had the same sequence, being identical to the 3 isolates that emerged at the end of July. These results suggest that a particular HEV 1c strain spread widely during the rainy season and was implicated in a small epidemic in the Kathmandu valley in August 1997.