Effects of ambient temperatures on clinical and immune responses of pigs infected with transmissible gastro-enteritis virus

Shimizu, M.; Shimizu, Y.

Two- to three-months-old pigs infected with transmissible gastroenteritis (TGE) virus showed no clinical response when housed at 30°C, but comparable infected pigs exposed to temperature changes from 30°C to 4°C following infection showed typical signs of TGE. Development of TGE-specific immune responses, as measured by blastogenic response of tissue lymphocytes, occurred at 3 days post-inoculation (DPI) in pigs held at 30°C, but not until 7 DPI in infected pigs held under the adverse conditions. Immunosuppression with corticosteroids resulted in a fall in circulatory T cells, lowering of non-specific blastogenic response of circulatory lymphocytes, and clinical signs of disease when immunosuppressed pigs were infected with TGE virus and held at 30°C. It is suggested that clinical responses to TGE virus infection may be affected by the influence of ambient temperatures on the immune responses of pigs.