DNA FOUND IN HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 PARTICLES MAY NOT BEREQUIRED FOR INFECTIVITY

We have studied the presence and significance of retroviral genome-der ived DNA in the core of human immunodeficiency virus (HIV) particles p roduced from transfections of HXB2 expression vectors in COS-7 cells a nd from HIV type 1 IIIB chronically infected H9 cells. Viruses purifie d by sucrose cushion centrifugation and treated with DNase I contained 1000-fold more viral RNA than DNA. However protease-defective viruses that contained only p160(gag-pol) had less than 100 times the amount of DNA in their cores than wild-type viruses suggesting that the p66/p 51 form of reverse transcriptase was responsible for DNA transcription . Viruses produced by transfections in the presence of 3'-azido-3'-deo xythymidine (AZT) contained the viral RNA genome but only DNA of prema ture length because of the chain terminating effects of AZT. However s uch viruses were as infectious for CD4(+) cells as wild-type virus. We conclude that retrovirus-derived DNA in HIV-1 particles is not requir ed for infection and does not play a significant role in this process.