Besides, the infection impairs LC functions by reducing the antigen-presenting ability and density of LCs; alter T-cell subsets, resulting in fewer CD4 + and CD8 + T cells and more infiltrating Tregs; decreases the CD4+/CD8 + T cell ratio to below 1; and induces greater T lymphocytes’ apoptosis, hence impairing cell-mediated immunity and accelerating the progression of CIN [33]. This evidence concerns the gene CD4 and infection.