Following initial transmission, the virus infects CD4+ cells, probably T lymphocytes, monocytes, or bone marrow-derived dendritic cells. Both during this initial stage and later in infection, the lymphoid system is a major site for the establishment and propagation of HIV infection. The gut-associated lymphoid tissue (GALT) plays a role in the establishment of infection and in the early depletion of memory CD4+ T cells.

Essentially all pts undergo a viremic stage during primary infection; in some pts this is associated with the “acute retroviral syndrome,” a mononucleosis-like illness (see below). This phase is important in disseminating virus to lymphoid and other organs throughout the body, and it is ultimately contained only partially by the development of an HIV-specific immune response.