Clinical and epidemiological implications of swine hepatitis E virus infection

In nonendemic areas, most patients with acute hepatitis E were infected thr ough traveling to endemic areas. However, some patients did not have a hist ory of foreign travel before infection. Furthermore, high seroprevalence ra tes of antibody to hepatitis E virus (anti-HEV) were found in the general a dult population in some countries without any recorded outbreak of hepatiti s E. The significance of anti-HEV assay in these subjects remains obscure. To study if swine might be a source of HEV infection, HEV was tested in ser a of 235 pigs in Taiwan, and from 5 patients with acute HEV infection who e ither denied or did not provide any foreign travel history. Three (1.3%) pi gs had detectable swine HEV RNA. The swine and human HEV strains from Taiwa n formed a monophyletic group, distinct from three previously reported grou ps: the United States human and swine HEV strains, the Mexico strain, and t he largest group composed of the Asian and the African strains. The identit y of nucleotide sequences was 84-95% between swine and human HEV strains in Taiwan, and 72-79% between Taiwan strains and those from different areas. The predicted amino acid sequence of a Taiwan swine HEV strain within the p eptide 3-2 used in commercial anti-HEV assay showed a high identity (91-94% ) with those of other human and swine HEV strains. Swine may be a reservoir of HEV and subclinical swine HEV infection may occur. Cross-reactivity of current anti-HEV assay may account for the high prevalence rate of anti-HEV in the general population in nonendemic areas. J. Mad. Virol. 60:166-171, 2000. (C) 2000 Wiley-Liss, Inc.