Cellular compartments of human immunodeficiency virus type 1 replication in vivo: determination by presence of virion-associated host proteins and impact of opportunistic infection.

Antigens derived from host cells are detectable in the envelope of human immunodeficiency virus type 1 (HIV-1) and result in a distinctive viral phenotype reflecting that of the host cell. An immunomagnetic capture assay targeting discriminatory host proteins was developed to differentiate between HIV-1 derived from macrophages and lymphocytes. HIV-1 propagated in macrophages or lymphocytes in vitro was selectively captured by monoclonal antibodies directed against the virally incorporated cell-type-specific host markers CD36 (macrophages) and CD26 (lymphocytes). Furthermore, by targeting these markers, virus of defined cellular origin was selectively captured from a mixed pool of in vitro-propagated viruses. This technique was further refined in order to determine the impact of opportunistic infection on HIV-1 expression from these cellular compartments in vivo. Analysis of cell-free virus purified from plasma of patients with HIV-1 infection suggested that in those with an opportunistic infection, viral replication occurred in activated lymphocytes. Interestingly, there was also significant replication in activated macrophages in those patients with untreated pulmonary tuberculosis. Thus, in addition to lymphocytes, the macrophage cellular pool may serve as an important source of cell-free HIV-1 in patients with opportunistic infections that lead to marked macrophage activation. This novel viral capture technique may allow researchers to address a wide range of important questions regarding virus-host dynamics.