Arch Virol (1998) 143: 1405–1415
Experimental infection of pigs with the newly identiﬁed swine
hepatitis E virus (swine HEV), but not with human strains of HEV
, P. G. Halbur
, J. S. Haynes
, T. S. Tsareva
, J. D. Bruna
R. H. Purcell
, and S. U. Emerson
Hepatitis Viruses Section, Laboratory of Infectious Diseases, National Institute of Allergy
and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, U.S.A.
College of Veterinary Medicine, Iowa State University, Ames, Iowa, U.S.A.
Accepted February 18, 1998
Summary. A novel virus of pigs, swine hepatitis E virus (swine HEV), was re-
cently identiﬁed and shown to be antigenically and genetically related to human
HEV. In the present study, we attempted to infect speciﬁc-pathogen-free (SPF)
pigs experimentally with swine HEV or with human strains of HEV. Serum sam-
ples collected from naturally infected pigs were used as the source of swine HEV.
Pigs inoculated intravenously with serum samples containing swine HEV sero-
converted to anti-HEV 4 to 8 weeks postinoculation, and the virus spread to an
uninoculated pig. Swine HEV was detected in nasal and rectal swab materials
as early as 2 weeks postinoculation and for 4 to 8 weeks thereafter. Viremia
appeared 4 to 6 weeks postinoculation and lasted 1 to 3 weeks. The inoculated
pigs appeared clinically normal and serum liver enzymes were not signiﬁcantly
elevated. In contrast, pigs were not infected when inoculated intravenously with
monkey infectious doses of one of two human strains of HEV (Sar-55
Hepatitis E virus (HEV), one of the causative agents of enterically transmitted
non-A, non-B hepatitis, is currently classiﬁed in the family Caliciviridae [15, 24],
although this classiﬁcation has been questioned . HEV is a single-stranded
RNA virus without an envelope [24, 27, 28]. The positive sense viral genome of
about 7.5 kb contains 3 open reading frames (ORFs). ORF1 probably encodes
viral nonstructural proteins, ORF 2 the putativecapsid protein and ORF3 a protein
of unknown function [5, 22, 24, 27, 28].