The observations that antibodies are predominantly class-switched IgG, that there is evidence of somatic mutation from germ-line Ig genes, that titers and affinity increase over time, and that there are numerous germinal centers within lymph nodes, all point to a significant T follicular helper (Tfh) CD4 cells-dependent antibody response to HIV-1 infection (Crotty, 2011). Here, CD4 is linked to HIV-1 infection.