The disease course in untreated human immunodeficiency virus (HIV) infection consists of an early acute phase characterized by extremely high viral loads and depletion of CD4+ T cells, followed by a largely asymptomatic chronic phase with more moderate viral loads and a slow loss of CD4+ T cell pool after partial recovery, and finally emergence of immunodeficiency, opportunistic infections and death. Here, CD4 is linked to Immunodeficiency.