ABSTRACT
Initiation of human immunodeficiency virus type 1 (HIV-1) reverse transcription occurs by extension of the cellular tRNA3(Lys) which anneals to the primer-binding site (PBS) on the 5' non-translated region of the viral RNA genome. The A-rich sequence (A-loop) upstream of the PBS interacts with the anticodon loop of tRNA3(Lys) and has been proposed to be essential for conferring specificity to tRNA3(Lys) for priming the initiation of HIV-1 reverse transcription. We observed that polyamide nucleic acid targeted to the A-loop sequence (PNAAL) exhibits high binding specificity for its target sequence. The PNAAL pre-bound to the A-loop sequence prevents tRNA3(Lys) priming on the viral RNA consequently blocking in vitro initiation of reverse transcription. Further, PNAAL can efficiently disrupt the preformed [tRNA3(Lys)--viral RNA] complex thereby rendering it non-functional for reverse transcription. The endogenous reverse transcription in disrupted HIV-1 virions containing packaged tRNA3(Lys) and its replicating enzyme RT was significantly inhibited by PNAAL, thus providing direct evidence of the involvement of the A-loop region of viral RNA genome in tRNA3(Lys) priming process. These findings suggest the potential of the A-loop region as a critical target for blocking HIV-1 replication.
Subject(s)
Genome, Viral , HIV-1/drug effects , Peptide Nucleic Acids/pharmacology , RNA, Transfer, Lys/genetics , Base Sequence , Binding Sites , DNA, Antisense/chemistry , DNA, Antisense/metabolism , DNA, Antisense/pharmacology , Dose-Response Relationship, Drug , HIV-1/genetics , HIV-1/metabolism , Molecular Sequence Data , Nucleic Acid Conformation , Nylons/chemistry , Peptide Nucleic Acids/chemistry , Peptide Nucleic Acids/metabolism , RNA, Transfer, Lys/chemistry , RNA, Transfer, Lys/metabolism , RNA, Viral/chemistry , RNA, Viral/drug effects , RNA, Viral/genetics , Transcription, Genetic/drug effectsABSTRACT
OBJECTIVE: The goal of this study was to identify in human immunodeficiency virus (HIV)-infected individuals immunologic markers that correlated with transmission of HIV by heterosexual contact. METHODS: In a case-control comparison of couples, immunologic and viral parameters were evaluated in 343 HIV-positive individuals who were members of 67 HIV-seroconcordant couples (both partners HIV positive) and 211 HIV serodiscordant couples (one positive, one negative). RESULTS: The most striking immunologic finding was the increased numbers of CD3+CD8+ cells found in the index member of discordant couples as compared to the index member of the concordant couples. Differences in CD3+CD8+ levels persisted after adjustment for stage of disease and CD3+CD4+ count. This increase in the number of CD3+CD8+ cells was accompanied by a concomitant decrease in the amount of viral replication measured by both HIV culture endpoint and quantitative RNA polymerase chain reaction (PCR). CONCLUSION: Data presented here further support the role of CD3+CD8+ cells in suppressing or controlling viral activity, although a causal role based on case-control data must be advanced cautiously. This in vivo biologic function may help prevent or lower the risk of HIV transmission.
