Serological evidence for swine hepatitis E virus infection in Australian pig herds

Hepatitis E virus (HEV) is an enterically transmitted human pathogen, with some similarities to caliciviruses. A variant of HEV was recently identified in pigs in the USA, infecting almost 100% of animals in commercial herds. Phylogenetic analysis suggests that this is a true 'swine HEV' distinct from the human virus, but the swine virus may also infect man. Using an in-house ELISA based on a highly conserved, recombinant HEV protein, we have examined collections of sera from Australian pigs for evidence of HEV infection in local pig herds. Sera from one research herd (n = 32) were uniformly non-reactive, and this was used to establish an assay cut-off (= mean + 3 SD of reference pig serum reactivities). Screening of sera from other herds demonstrates that swine HEV is I,resent in Australia, with reactivity observed in 30% (12/40) of random samples from two piggeries, 92-95% of pigs by the age of 16 weeks in two other piggeries (n = 45), and 17% (15/59) of wild-caught pigs. Further studies are required to examine whether HEV causes disease in pigs and to determine the risk of swine HEV transmission to man. (C) 1999 Elsevier Science B.V. All rights reserved.