Humoral and cellular responses in swine exposed to transmissible gastroenteritis virus.

Swine exposed to attenuated transmissible gastroenteritis virus had higher virus-neutralizing antibody titers than did swine exposed to virulent virus. The cellular response, measured by the direct leukocyte migration-inhibition (LMI) procedure, was greater in swine exposed to virulent virus than in swine exposed to the attenuated virus. Leukocytes from exposed swine were inhibited more in the LMI procedure in the presence of the homologeous sensitizing antigen than in the presence of the heterologous viral antigen. The humoral response measured by virus neutralizing reached a peak 21 days after exposure, and the cellular response measured by LMI reached a peak 28 days after exposure.