HIV-2 Vpx-mediated enhancement of virus infection of macrophages. (A) Macrophages were transduced with the VSV-G pseudotyped wild-type HIV-1 NL4-3 and SIVmac239 IRES-eGFP virions (panels 1 and 2) or a VSV-G pseudotyped vpx-defective SIVmac239 IRES-eGFP construct produced in the presence of pCGCG vectors expressing eGFP alone (panel 3) or together with the indicated Vpx proteins (panels 4–10). Virus stocks were produced by transient transfection of 293T cells. High infection rates were associated with increased rates of apoptosis and thus reduced numbers of cells analyzed in some experiments. (B) Average percentages and SDs of virally infected GFP+ cell levels detected in macrophages derived from four different donors quantified by flow cytometric analysis at four days post-transduction. Virus infectivity was normalized to infection of TZM-bl indicator cells. (C) Enhancement of macrophages infection by vpx alleles derived from HIV-2-infected individuals grouped based on their viral loads and the infecting viruses. See legend to figure 3 for further detail.