Infection dynamics of hepatitis E virus in naturally infected pigs in a Chinese farrow-to-finish farm

To analyze the changes that occur in pigs during hepatitis E virus (HEV) infection, 256 serial serum samples were obtained from 32 pigs from one pig farm at ages 0 (cord blood), 15, 30, 60, 75, 90, 120, and 150 days. All HEV markers were assayed in these samples and showed that total anti-HEV antibodies and IgG formed two peaks. The first peak occurred at 0-60 days and the second after 75 days. No markers of infection, such as HEV RNA, antigen and anti-HEV IgM, were detectable during the first peak. Most newborn piglets (<24 h of age) were negative for total anti-HEV and IgG. However, colostrum from all of the sows had evidence of these antibodies. Thus, the anti-HEV in the first peak was assumed to be acquired from maternal milk. Some infectious markers were positive at the beginning of second peak. PCR products were cloned and sequenced and the results indicated those sequences belonged to HEV genotype 4. The antibody present during the second peak may be induced by natural infection with HEV. In conclusion, pigs are susceptible to HEV infection and may remain infectious after the first peak of anti-HEV antibody. (C) 2011 Elsevier B.V. All rights reserved.