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.