L. plantarum was shown to increase the frequency of regulatory T cells while decreasing responsiveness of Th2 cells and increasing responsiveness of CD8+ T cells in the spleen and/or mesenteric lymph nodes, suggesting a role for this species in modulating Th2-mediated allergic disease and host response to viral infections that require activation of CD8+ T cells. The gene discussed is CD8A; the disease is viral infectious disease.