Abstract
Subtype C and A HIV-1 strains dominate the epidemic in Africa and Asia, while sub-subtype A2 is found at low frequency only in West Africa. To relate Gag processing in vitro with viral fitness, viral protease (PR) enzymatic activity and in vitro Gag processing were evaluated. The rate of sub-subtype A2 Gag polyprotein processing, as production of the p24 protein, was reduced compared to subtype B or C independent of PR subtype, indicating that subtype A2 Gag qualitatively differed from other subtypes. Introduction of subtype B matrix-capsid cleavage site in sub-subtype A2 Gag only partially restored the processing rate. Unique amino acid polymorphism V124S at the matrix-capsid cleavage site, together with other polymorphisms at non-cleavage sites, are differentially influencing the processing of Gag polyproteins. This genetic polymorphisms landscape defining HIV-1 sub-subtypes, subtypes and recombinant forms are determinants of viral fitness and frequency in the HIV-1 infected population.
Highlights
The polymorphism at matrix-capsid cleavage site, together with non-cleavage sites polymorphisms, direct the processing rate of the substrate, not the intrinsic activity of the enzyme.
The less prevalent and less infectious sub-subtype A2 harbors the matrix-capsid cleavage site polymorphism that we report as a limiting factor for gag processing.
Sub-subtype A2 Gag polyprotein processing rate is independent of the PR subtype.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Funding This study was supported in part by NIH R01 AI28571; Stephany W. Holloway University Chair for HIV/AIDS Research (M.M.G.); and Laura McClamma Fellowship (C.M. and R.M.C.). All authors declare no conflict of interest.
Transparency declarations: None to declare.