IDENTIFICATION AND CHARACTERIZATION OF A PORCINE TOROVIRUS

A porcine torovirus (PoTV) was identified and characterized; it is a n ovel member of the genus Torovirus (family Coronaviridae, order Nidovi rales), closely related to but clearly distinct from the already recog nized equine torovirus (ETV) and bovine torovirus (BoTV) representativ es. Immunoelectron microscopy of feces from piglets revealed elongated , 120- by 55-nm particles which were recognized by a torovirus-specifi c antiserum. Amplification by reverse transcriptase (RT) PCR with prim ers designed to detect conserved regions (on the basis of the genomes of BoTV strain Breda and ETV strain Berne) resulted in the identificat ion of the 489-bp nucleocapsid gene, encoding a 18.7-kDa protein, The sequence identity in this region between PoTV and both ETV and BoTV wa s only about 68%, whereas the latter two show 81% identity. Neutralizi ng antibodies directed against ETV were found in sera of adult and you ng pigs, In all 10 herds sampled, seropositive animals were present, a nd 81% of randomly selected adult sows possessed antibodies. A longitu dinal study with RT PCR showed that piglets shed virus in the feces fo r 1 or more days, starting 4 to 14 days after weaning.