Local and systemic cell-mediated immunity against transmissible gastroenteritis, an intestinal viral infection of swine.

The occurrence of local and systemic cell-mediated immunity (CMI) in swine against transmissible gastroenteritis (TGE) virus, a coronavirus that infects the epithelial cells of the small intestine of swine, has been investigated. Leukocyte suspensions prepared from intestinal lamina propria (LP) and spleen were each incubated with and without inactivated TGE virus. The supernatants from these cultures were tested for the presence of macrophage migration inhibition factor (MIF) by the indirect MIF test using guinea pig peritoneal exudate cells as the source of macrophages. All swine serologically negative for TGE antibodies (i.e., unexposed to TGE virus) were also negative for MIF production by lymphocytes from both sources. In 10 of 10 animals given TGE virus subcutaneously, MIF production by splenic lymphocytes was significantly greater (p less than or equal to 0.01) than by LP lymphocytes, and in 9 of 10 of these animals MIF production by LP lymphocytes was negligible (percentage of inhibition of migration less than 3%).