Influence of Gag-Protease-Mediated Replication Capacity on Disease Progression in Individuals Recently Infected with HIV-1 Subtype C
- Jaclyn K. Wright ,
- Vladimir Novitsky ,
- Mark A. Brockman ,
- Zabrina L. Brumme ,
- Chanson J. Brumme ,
- Jonathan M. Carlson ,
- David Heckerman ,
- Bingxia Wang ,
- Elena Losina ,
- Mopo Leshwedi ,
- Mary van der Stok ,
- Lungile Maphumulo ,
- Nompumelelo Mkhwanazi ,
- Fundisiwe Chonco ,
- Philip J. R. Goulder ,
- Max Essex ,
- Bruce D. Walker ,
- Thumbi Ndung'u
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HLA class I-mediated selection of immune escape mutations in functionally important Gag epitopes may partly explain slower disease progression in HIV-1-infected individuals with protective HLA alleles. To investigate the impact of Gag function on disease progression, the replication capacities of viruses encoding Gag-protease from 60 individuals in early HIV-1 subtype C infection were assayed in an HIV-1-inducible green fluorescent protein reporter cell line and were correlated with subsequent disease progression. Replication capacities did not correlate with viral load set points (p=0.37) but were significantly lower in individuals with below median viral load set points (p=0.03), and there was a trend of correlation between lower replication capacities and slower rates of CD4 decline (p=0.09). Overall, the proportion of host HLA-specific Gag polymorphisms in or adjacent to epitopes was negatively associated with replication capacities (p=0.04) but host HLA-B-specific polymorphisms were associated with higher viral load set points (p=0.01). Further, polymorphisms associated with host-specific protective HLA alleles were linked with higher viral load set points (p=0.03). These data suggest that transmission or early HLA-driven selection of Gag polymorphisms results in reduced early cytotoxic T-lymphocyte (CTL) responses and higher viral load set points. In support of the former, 46 percent of individuals with non-protective alleles harboured a Gag polymorphism exclusively associated with a protective HLA allele, indicating a high rate of their transmission in sub-Saharan Africa. Overall, HIV disease progression is likely to be affected by the ability to mount effective Gag CTL responses as well as the replication capacity of the transmitted virus.