The kinetics of human immunodeficiency virus reverse transcription are slower in primary human macrophages than in a lymphoid cell line.

Reverse transcription is a critical event in the life of a retrovirus and a potential determinant of viral infectivity. The kinetics of "endogenous" reactions are relatively well defined but little is known about HIV reverse transcription during infection. In this report, we have estimated the rate and efficiency of HIV-1 reverse transcription in primary macrophages and H9 lymphoid cells using quantitative PCR to detect intermediate cDNA structures. DNA synthesis is completed 12-16 hr after infection of H9 cells, but requires more than 36 hr in M phi, owing to slower rates of extension and template switching. Reverse transcription was inefficient in both cell types and in H9 cells the kinetics were sufficiently well resolved to estimate that only one in three transcripts initiated were extended to full-length viral DNA. Slower DNA synthesis largely accounts for the longer replicative cycle of HIV in macrophages. The rate of reverse transcription, which may depend upon levels of deoxynucleotide triphosphate substrates, is a potential factor in modulating the permissiveness of macrophage populations in vivo.