| Summary: | <p>Abstract</p> <p>Background</p> <p>All human immunodeficiency virus (HIV-1) uses a host tRNA<sup>Lys,3 </sup>as the primer for reverse transcription. The tRNA<sup>Lys,3 </sup>is bound to a region on the HIV-1 genome, the primer-binding site (PBS), that is complementary to the 18 terminal nucleotides of tRNA<sup>Lys,3</sup>. How HIV-1 selects the tRNA from the intracellular milieu is unresolved.</p> <p>Results</p> <p>HIV-1 tRNA primer selection has been investigated using viruses in which the primer-binding site (PBS) and a sequence within U5 were altered so as to be complementary to tRNA<sup>Met</sup>, tRNA<sup>Pro </sup>or tRNA<sup>Ile</sup>. Analysis of the replication of these viruses in human peripheral blood mononuclear cells (PBMC) revealed preferences for the selection of certain tRNAs. HIV-1 with the PBS altered to be complementary to tRNA<sup>Met</sup>, with and without the additional mutation in U5 to be complementary to the anticodon of tRNA<sup>Met</sup>, stably maintains the PBS complementary to tRNA<sup>Met </sup>following extended <it>in vitro </it>culture in PBMC. In contrast, viruses with either the PBS or PBS and U5 mutated to be complementary to tRNA<sup>Ile </sup>were unstable during <it>in vitro </it>replication in PBMC and reverted to utilize tRNA<sup>Lys,3</sup>. Viruses with the PBS altered to be complementary to tRNA<sup>Pro </sup>replicated in PBMC but reverted to use tRNA<sup>Lys,3</sup>; viruses with mutations in both the U5 and PBS complementary to tRNA<sup>Pro </sup>maintained this PBS, yet replicated poorly in PBMC.</p> <p>Conclusion</p> <p>The results of these studies demonstrate that HIV-1 has preferences for selection of certain tRNAs for high-level replication in PBMC.</p>
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