Age-related impaired Th1 responses to PRV vaccine in vivo in aged pigs.

Murine model studies have shown that function of the immune system declines with aging, but data on aged pigs are scarce. Many physiological and pathophysiological data of pigs can be transferred to human, research in pigs is important to confirm murine data, therefore, aged pigs were chosen as an aged animal model. In this study, we demonstrated an age-related decline in Th1 responses in vivo to PRV vaccine in the pig model, and this decline in type 1 immune responses was associated with reduced PRV-specific T cell proliferation, IgG2/IgG1, and Th1 cytokines production. More importantly, these impaired Th1 responses correlated with reduced CD4(+) T cells and markedly increased CD4(+)CD8(+) T cells. Taken together, these data demonstrated that there was a decline in Th1 immune responses to PRV vaccine with aging in pigs, which may help to explain the age-related decline in vaccine efficacy and increase in morbidity and mortality of infectious diseases.