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 identifie d in pigs in the USA, infecting almost 100% of animals in commercial herds. Phylogenetic analysis suggests that this is a true 'swine HEV' distinct fr om the human virus, but the swine virus may also infect man. Using an in-ho use ELISA based on a highly conserved, recombinant HEV protein, we have exa mined collections of sera from Australian pigs for evidence of HEV infectio n in local pig herds. Sera from one research herd (n = 32) were uniformly n on-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 d emonstrates that swine HEV is I,resent in Australia, with reactivity observ ed in 30% (12/40) of random samples from two piggeries, 92-95% of pigs by t he 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 di sease in pigs and to determine the risk of swine HEV transmission to man. ( C) 1999 Elsevier Science B.V. All rights reserved.