Vpx is critical for reverse transcription of the human immunodeficiency virus type 2 genome in macrophages.

The abilities of wild-type and vpx-defective human immunodeficiency virus type 2 (HIV-2) clones to synthesize viral DNA in human monocyte-derived macrophages (MDMs) and lymphocytic cells were comparatively and quantitatively evaluated. While the vpx-defective mutant directed the synthesis of viral DNA comparably to the wild-type virus and normally in lymphocytic cells, no appreciable viral DNA was detected in MDMs infected with the mutant. To substantiate this finding and to determine whether there is some specific region(s) in Vpx crucial for viral DNA synthesis in MDMs, we generated a series of site-specific point mutants of vpx and examined their phenotypes. The resultant five mutants, with no infectivity for MDMs, showed, without exception, the same defect as the vpx-defective mutant. Our results here clearly demonstrated that the entire Vpx protein is critical for reverse transcription of the HIV-2 genome in human MDMs.