INCOMPLETELY REVERSE-TRANSCRIBED HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 GENOMES IN QUIESCENT CELLS CAN FUNCTION AS INTERMEDIATES IN THE RETROVIRAL LIFE-CYCLE

Using a quantitative polymerase chain reaction (PCR) method, we have previously shown that a molecularly cloned isolate of human immunodeficiency virus type 1 (HIV-1) can efficiently enter quiescent primary lymphocytes; however, the reverse transcription process is not completed in these cells. In this study, we further characterized the reverse transcription of HIV-1 in quiescent cells, and our results indicate that while initiation of reverse transcription occurs simultaneously in both activated and quiescent lymphocytes, it not only ends prematurely but also proceeds more slowly in quiescent cells. We also performed experiments to address the role of partial reverse transcripts as intermediates in the viral life cycle. We used azidothymidine either before or after infection with HIV-1 to prevent formation of and further DNA synthesis by partial reverse transcripts, respectively. Decreases in virus production from these cells following mitogenic stimulation indicated that partial reverse transcripts can contribute significantly to virus rescue from infected quiescent cells stimulated subsequent to infection. Furthermore, we established that mitogenic stimulation of infected quiescent cells induces reinitiation of DNA synthesis from partial reverse transcripts. However, the virus rescue is inefficient relative to the initial multiplicity of infection, and this is explained by inefficient completion of DNA synthesis from the partial reverse transcript. Thus, the arrest of reverse transcription in quiescent cells may play an important role in HIV-1 pathogenesis by contributing to the inefficient infection of potential target cells in the peripheral blood of HIV-1-infected individuals.