Physiologically, host defenses against viral infections rely on mechanical barriers and innate immunity (mainly through Toll-like receptors signaling or DExD/H box RNA helicases) (51), and subsequently adaptive immunity responses activation (through the interaction of activated B cells and CD4+ T cells to initiate the process of somatic hypermutation and affinity maturation for the selection of long-lived high-affinity and antibody producing plasma cells and memory B cells) (52). The gene discussed is CD4; the disease is viral infectious disease.