Analysis of the helicase gene of Korean swine hepatitis E virus isolates and trends in viral infection.

Hepatitis E virus (HEV) has been considered to be a zoonotic agent and an important public concern worldwide. In this study, a nested RT-PCR was developed to detect the helicase gene of swine HEV (sHEV) from sera of pigs. Using this RT-PCR, 16 out of 821 Korean isolates of sHEV were identified, with 1.9% prevalence. An age-specific prevalence was demonstrated with the highest prevalence in growing pigs (5.4%). Phylogenetic analysis of sHEV Korean isolates identified genotype 3, with 89.4-99.9% nucleotide sequence identity. The viruses were closely related to US and Japanese HEV isolates from swine and humans (89.4-93.1%). The prevalence of anti-HEV IgG in individual pigs and swine herds was 39.5 and 80%, respectively. The seroprevalence rate increased in proportion to the age of the swine. The seroprevalence of HEV was higher than previously reported. These results indicate that sHEV is widespread in Korean swine herds and further raise concerns about possible zoonosis.