CD4 and viral infectious disease: In this study, IFN-transformed B. longum increased the expression of Th1 cytokines (IFN-γ and TNF-α) mRNA in cardiac tissue and enhanced the secretion of Th1 cytokines (IFN-γ and TNF-α) from splenocytes, which suggested that this recombinant B. longum is able to induce expression of CD4+ Th1 cells against virus infection.