Abstract
Amino acid substitutions at HIV-1 Gag p7/p1 and p1/p6 cleavage sites may be selected under antiretroviral pressure or represent natural polymorphisms. Whether changes are associated with specific protease(PR) mutation patterns and different clinical evolution has not been investigated. p7/p1 and p1/p6 cleavage site sequences from sera from 110 patients infected with HIV-1 were compared by regression analysis, using clinical, laboratory, and sequence variables, and the evolution of CD4+ cell counts and viral load over time. Sixteen of 35 (46%) individuals naive to PR inhibitors (PIs), and 49 of 75(65%) receiving PI-containing regimens had a p7/p1 and/or p1/p6 cleavage site polymorphism (p = 0.06). A431V and/or L449F were present exclusively among individuals failing PI treatment (17 of 75 [23%] and 3 of 75 [3%], respectively). There was a significant association between A431V and PR M46I,L (OR 13.7; 95% CI 4.2-44.3) and V82A,F,T (OR 8.8; 95% CI 2.7-27.8). Natural polymorphism P453L was strongly associated with the selection of PR I84V (OR 49.5; 95% CI 12-212) and selected against V82 mutation (OR 0.15; 95% CI 0.02-1.2). After a median followup of 15 months, no polymorphism was associated with parameters of disease progression among individuals failing treatment. Only a limited set of amino acid substitutions can be tolerated at p7/p1 and p1/p6 cleavage sites. A431V is selected in association with specific PR inhibitor mutations. Natural polymorphism P453L might direct the PR resistance pathway through I84V instead of V82 mutation. No short-term clinical impact of cleavage site substitutions was documented.
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