The three recognized stages of HIV infection, acute infection, chronic infection, and AIDS, are defined by viral load, CD4+ T cell count, as well as clinical progression; however, prior to the appearance of acute infection symptoms, there is an initial eclipse phase (up to 10 days) in which infection is established at the exposure site, while viral load has not yet reached detectable levels in the circulation [31]. The gene discussed is CD4; the disease is infection.