title: A double-protease-resistant variant of transmissible gastroenteritis virus and its ability to induce lactogenic immunity.
abstract: A virus resistant to 2 major intestinal proteases (trypsin and alpha-chymotrypsin) was derived from the attenuated Purdue strain of transmissible gastroenteritis virus. Its enzymatic stability was confirmed, in vitro, by exposure to proteolytic enzymes and to porcine intestinal fluids. Vaccination of 5 seronegative pregnant sows with the variant virus by a series of 2 oral and 1 IM inoculations resulted in high titers of neutralizing antibody in serum and colostrum. The mean antibody titer in milk whey decreased 44-fold within 1 week after parturition. At 3 days of age, the 40 pigs delivered by these sows were challenge exposed orally with virulent transmissible gastroenteritis virus. Pigs nursing the 5 vaccinated sows underwent a relatively mild clinical course of illness. The average mortality of these 40 pigs was 33%. Thirty-six pigs which had been raised by 4 nonvaccinated sows had a more severe illness, greater daily weight loss, and higher mortality (92%).
mesh_terms: D000818:Animals; D000833:Animals, Suckling / Q000276:immunology; D000914:Antibodies, Viral / Q000096:biosynthesis; D002918:Chymotrypsin / Q000494:pharmacology; D003126:Colostrum / Q000276:immunology*; D003332:Coronaviridae / Q000276:immunology*; D004352:Drug Resistance, Microbial; D005260:Female; D005761:Gastroenteritis, Transmissible, of Swine / Q000276:immunology* / Q000401:mortality; D014644:Genetic Variation; D008892:Milk / Q000276:immunology*; D009500:Neutralization Tests; D011247:Pregnancy; D013552:Swine / Q000276:immunology*; D005760:Transmissible gastroenteritis virus / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D014357:Trypsin / Q000494:pharmacology; D014611:Vaccination / Q000662:veterinary; D014613:Vaccines, Attenuated / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines; D002918:Chymotrypsin; D014357:Trypsin