Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 2, 2000
Publication Date: July 3, 2000
Technical Abstract: A bovine viral diarrhea virus isolate (BVDV-Woods) pathogenic for neonatal pigs was serendipitously discovered in our laboratory. BVDV-Woods was inadvertently introduced, via contaminated fetal bovine serum, into a transmissible gastroenteritis virus (TGEV-Miller 3) culture propagated on McClurkin swine testicular (ST) cells and maintained for 50 serial passages, as determined retrospectively. The BVDV-Woods and TGEV-Miller 3 were subsequently co-purified by limiting dilution and purity was assessed by immunocytochemistry and RT-PCR. Analysis of the 5' untranslated region of BVDV-Woods revealed 97.3% sequence identity with BVDV-NY1. Caesarian- derived colostrum-derived (CDCD) piglets were inoculated with 1) BVDV- Woods, or 2) BVDV-NY1, or 3) TGEV-Miller 3, or 4) BVDV-Woods and TGEV- Miller 3, or 5) BVDV-NY1 and TGEV-Miller 3, or 6) non-infected ST culture. Piglets inoculated with BVDV-Woods alone or in combination with TGEV-Miller r3 developed severe diarrhea and histopathologic lesions consisting of atrophy and fusion of small intestine villi, and subtotal lymphocyte depletion of Peyer's patches, spleen, and thymus. Pigs inoculated with TGEV-Miller 3 developed similar intestinal lesions, but did not have lymphocyte depletion of primary and secondary lymphoid organs. Pigs inoculated with BVDV- NY1 did not develop diarrhea or lesions, but those inoculated with TGEV + BVDV-NY1 had generalized lymphoid depletion of variable severity in addition to lesions consistent with viral enteritis. The results indicate that BVDV-Woods can be highly pathogenic in pigs and that nonpathogenic BVDV strains may act synergistically with TGEV to deplete lymphoid organs.