Immunology of Transmissible Gastroenteritis

Abstract

SUMMARY Transmissible gastroenteritis ( tge ) is caused by a virus having many of the characteristics of the coronavirus group. Only 1 serologic type has been described. Antibody production by infected or vaccinated animals readily occurs and is demonstrable by neutralization tests. Immunity exists when the epithelial cells of the small intestines have increased resistance or are protected against viral infection. Active immunity against clinical signs occurs, for a variable period, after infection with virulent virus. The mechanism of active immunity is not known but it does not appear to be due to circulating antibody. Passive immunity is provided to pigs which are nursing immune sows. This immunity is probably dependent on the continual presence of neutralizing antibodies in the lumen of the alimentary tract, as obtained from ingesting colostrum or milk. Preliminary evidence suggests that tge antibodies of the immunoglobulin (Ig)A class are more important than those of the IgG class in providing passive immunity. The IgA antibodies were demonstrable in milk of sows recovered from infection with virulent tge virus, but not in those given parenteral injections of live attenuated virus. In the latter, IgG antibodies predominated.