Prevalence of hepatitis E virus antibodies in Canadian swine herds and identification of a novel variant of swine hepatitis E virus

Swine hepatitis E virus is a newly identified potentially zoonotic virus fr om pigs of particular concern for possible direct transmission to a human x enotransplant recipient by organ transplantation. In the present study, pre valence of serum antibodies to hepatitis E virus was examined in Canadian s wine herds. A total of 998 serum samples collected from 6-month-old healthy slaughter hogs were examined by enzyme immunoassay and Western blot analys is for antibodies to the recombinant open reading frame 3 (ORF3) protein of hepatitis E virus expressed in Escherichia coli. These samples represented more than 80 different swine production units from five major swine-produc ing provinces across Canada. From this study, 594 samples (59.4%) were foun d to be positive for hepatitis E virus antibody. The seroprevalence was hig her in Quebec (88.8%) and Ontario (80.1%) than in Alberta and Saskatchewan (38.3%). By PCR using a pair of oligonucleotide primers deduced from the OR F2 sequence of human hepatitis E virus, a specific hepatitis E virus sequen ce was recovered from feces of pigs. The nucleotide sequence identity betwe en the U.S. swine hepatitis E virus and the Canadian isolate (SK3) was only 85.8%, suggesting that genotypic variations may exist in swine hepatitis E virus in North America. Among 165 serum samples collected from humans in S askatchewan, 2.4% were found to be positive for antibodies to the hepatitis E virus ORF3 protein. Our data indicate that hepatitis E virus is highly p revalent in commercial swine populations in Canada and support the suggesti on that the swine hepatitis E virus may be an important zoonotic agent for humans.