Effect of Altering the tRNA [Formula: see text] Concentration in Human Immunodeficiency Virus Type 1 upon Its Annealing to Viral RNA, GagPol Incorporation, and Viral Infectivity

Human immunodeficiency virus type 1 (HIV-1) uses tRNA [Formula: see text] as a primer for reverse transcription and, during viral assembly, this tRNA is selectively packaged into the virus along with the other major tRNA(Lys), tRNA [Formula: see text]. Increasing the cytoplasmic concentration of tRNA [Formula: see text] through transfection of cells with a plasmid containing both HIV-1 proviral DNA and a tRNA [Formula: see text] gene results in a greater incorporation of tRNA [Formula: see text] into virions, which is accompanied by increased annealing of tRNA [Formula: see text] to the viral genome and increased infectivity of the viral population. Increased viral tRNA [Formula: see text] is accompanied by decreased viral tRNA [Formula: see text] , with the total tRNA(Lys)/virion and the GagPol/Gag ratios remaining unchanged. Viral tRNA(Lys) can be doubled, with increases in both tRNA [Formula: see text] and tRNA [Formula: see text] concentrations, by overexpressing lysyl tRNA synthetase. This also results in increased tRNA [Formula: see text] annealing to the viral RNA and increased viral infectivity but, again, no change in the GagPol/Gag ratio was observed. This result indicates that GagPol, whose interaction is required during packaging, is not a limiting factor during tRNA(Lys) incorporation into HIV-1, whereas LysRS is.