Prevalence of IgG antibodies to hepatitis E virus (IgG-anti-HEV) was determined among different animal species from India. Seropositivity varied from 4.4% to 6.9% in cattle, 54.6-74.4% in pigs and 2.1-21.5% in rodents. Of the 44 dogs screened, 10 were positive (22.7%). None of the 250 goat sera tested were found to be anti-HEV positive. Among rodents, over 50% serum samples collected in 1985 from Bandicota bengalensis were positive for anti-HEV antibodies. No evidence of HEV infection was obtained following experimental inoculation of an Indian strain (AKL-90) of HEV into anti-HEV negative pigs and goats. The results document varied prevalence of anti-HEV antibodies in different animal species from India and of inability of Indian pigs and goats to support replication of at least one human strain of HEV.

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The results suggest that, in countries where HEV is endemic, the transmission of hepatitis E may be associated with blood transfusion.

Of 200 voluntary blood donors screened for hepatitis E virus (HEV) RNA, employing the reverse transcription-polymerase chain reaction (RT-PCR), three were found to be positive (1.5%). None of the HEV RNA-positive blood donors had any symptoms at the time of blood donation or during subsequent follow-up. One donor was positive for immunoglobulin M (IgM) antibodies to HEV, with a raised serum alanine aminotransferase (ALT) level, whereas the other two donors were negative for both immunoglobulin G (IgG) and IgM antibodies to HEV. Follow-up blood samples collected 2-5 months later from HEV RNA-positive blood donors demonstrated the presence of IgG anti-HEV antibodies. Overall seroprevalence of IgG anti-HEV was 18.6%. Retrospective studies on samples collected from commercial blood donors and haemophiliacs revealed IgG anti-HEV positivity to be 24. 6% (46/191) and 24.4% (22/90) and statistically not different (P>0. 1) from the prevalence among voluntary blood donors and an age-matched normal population, respectively. However, a highly significant proportion of the paid plasma donors, with a high prevalence of IgG antibodies to human immunodeficiency virus and hepatitis C virus, were positive for IgG antibodies to HEV (54/71, 76%, P<0.001), indicating a possible role of blood-derived HEV in the transmission of the virus among plasma donors. These results demonstrate the possible risk of transfusion-associated hepatitis E in hyperendemic areas.

Open reading frame 2 proteins (ORF2) from swine (genotype 4, S-ORF2) and human (genotype 1, H-ORF2) hepatitis E virus (HEV) having 91.4% identity at amino acid level were expressed using baculovirus expression system. Comparison of ELISAs based on the two proteins yielded identical results when sequential serum samples from monkeys and pigs experimentally infected with genotypes 1 and 4 HEV, respectively, were tested. Samples from patients (n = 258) suffering from non-A, non-B hepatitis during outbreaks of the disease and 180 sera from apparently healthy children were screened by H-ORF2-, S-ORF2-based ELISAs and Genelabs ELISA, a widely used commercial test for HEV diagnosis. Specificity of all three tests in detecting IgM and IgG antibodies in healthy children was comparable. Excellent correlation was noted in detecting both IgM (98.7% concordance) and IgG (97.7% concordance) anti-HEV antibodies when H-ORF2 and S-ORF2 ELISAs were compared. When compared with Genelabs ELISA, both H-ORF2 and S-ORF2 ELISAs identified 34 and 18 additional positives, respectively, in IgM and IgG anti-HEV tests showing comparatively less sensitivity of the commercial assay. The concordance of Genelabs ELISA in IgM detection was 86.4% and 85.6%, respectively, with H-ORF2 and S-ORF2 ELISAs. The concordance between Genelabs ELISA and H-ORF2 decreased further to 73.6% when 129 human samples from recent HEV epidemics (2002-2004) were tested for IgM. Similar results were obtained when sequential samples from 11 hepatitis E patients were examined. Screening of serum samples from 137 sporadic non-A, non-B hepatitis cases further confirmed the superiority of the H-ORF2 and S-ORF2 ELISAs. All 36/137 HEV-RNA-positive samples from sporadic cases belonged to genotype 1 confirming absence/rarity of type 4 human infections. H-ORF2 and S-ORF2 antigens were swappable in ELISAs for detecting both genotypes 1 and 4 HEV infections.