Initiation of in vitro reverse transcription from tRNA Lys3 on HIV-1 or HIV-2 RNAs by both type 1 and 2 reverse transcriptases

Abstract

HIV reverse transcription is initiated from a cellular tRNA partially associated with the retroviral genome. Here we studied homologous HIV-2 cDNA synthesis using natural or synthetic primers. With natural tRNA Lys3, synthesis of early products comprising nucleotides +5 to +7 preceded the elongation step leading to synthesis of (−) strong-stop cDNA. In the presence of a poly(A)·oligo(dT) trap, no full-length product was observed while early products were still present, showing a transition between initiation and elongation. With DNA primers only an unspecific elongation was found. Our data show a similar mechanism of reverse transcription initiation by HIV-1 and HIV-2 reverse transcriptases. Furthermore, using a heterologous system we found that HIV-1 RNA, in contrast to data reported in the literature, was an excellent template for HIV-2 reverse transcriptase.