Dynamics of gag-pol minority viral populations in naive HIV-1-infected patients failing protease inhibitor regimen

Objective Recently, we have reported the role of baseline gag cleavage site mutations on the virological outcome of a dual-boosted protease inhibitor regimen in antiretroviral-naive patients (2IP-ANRS 127 trial). The objective of this substudy was to characterize, in patients experiencing virological failure, from the 2IP-ANRS 127 trial, the viral quasispecies present at baseline and at virological failure in gag cleavage site, in gag-pol frameshift and in protease-coding region. Methods In four patients, we analysed by clonal analysis the viral population in gag cleavage site (p17/p24, p24/p2, p2/p7, p7/p1, p1/p6(gag)), in p6(gag), in gag-pol frameshift [p1/transframe protein (TFP)/p6(pol)] and in protease-coding region. Results Clonal analysis of protease-coding region failed to detect major as well as minor protease inhibitor resistance-associated mutations in all four patients. In one patient, a I15V-mutated variant increased from 13 to 100% between baseline and week 24. Clonal analysis of gag and gag-pol cleavage site showed an increase in specific viral populations in p2/p7 cleavage site between baseline and virological failure in three patients. Among them, we described in one patient, that the predominant population at virological failure harboured in p2/p7 and TFP/p6(pol)-specific genotypic profiles associated with duplication of the P(T)APP motif in p6(gag) and the I15V protease mutation on the same individual molecular clones. Conclusion We highlighted the emergence of minority viral populations in the p2/p7 cleavage site between baseline and virological failure. In addition, we showed the association of a specific protease mutation with gag and gag-pol cleavage site substitutions, suggesting their possible role in virological outcome.