CD4+ IL-17-producing cells, designated as Th17 cells, can enhance the Th1 response and aid in promoting cytotoxic T-cell activity during viral infections [46], and a similar increase in the frequency of IL-17-producing CD4+ T cells was identified in the splenocytes of mice vaccinated with CC-OMV-M2e. The gene discussed is CD4; the disease is viral infectious disease.