Vpx association with mature core structures of HIV-2.

Vpx is a virion-incorporated protein encoded by HIV-2 and certain strains of SIV which is necessary for efficient infection of lymphocytes and macrophages. To determine the location of Vpx within the HIV-2 particle, core structures were obtained from mature HIV-2 virions. Analysis of purified cores reveal the presence of monomeric Vpx as well as a nondenaturable and nonreducible higher order Vpx complex. Characterization of the core-associated Vpx complex suggests it to be a Vpx homodimer, indicative of high concentrations of Vpx. The incorporation and concentration of Vpx in HIV-2 cores support the hypothesis that it functions within the viral preintegration complex.