HIV-1 subtype C envelope (Env) region amino acid length polymorphism and glycosylation sites variation; correlations with markers of disease progression among 7 antiretroviral therapy naïve heterosexuals

Abstract

HIV env gp120 characteristics associated with disease progression have so far shown conflicting
results, yet such information may provide insight into HIV-1 vaccine design. Env C2V5 characteristics
associated with immunological and virological markers of disease progression were assessed among 7
HIV-1 subtype C infected but antiretroviral therapy naïve heterosexuals. Amino acid sequence lengths
and potential N-glycosylation sites (PNGs) were counted and regression analysis was used to assess
associations with plasma viral load and CD4 count. Each unit increase in PNGs or amino acid sequence
length within C2V5 region was associated with a 340000 or 110000 copies/ ml decrease in viral load,
p=0.001 or 0.005, respectively. Viral load suppressions of 720000 and 2 000000 copies/ml were observed
for each unit increase in PNGs within the C3 and C4 sub-regions; p=0.035 and <0.001, respectively.
Each unit increase in amino acid sequence length within the V3 region correlated with a 129 cell
increase in CD4 count. Increases in PNGs within the C3 and C4 sub-regions could be central in viral
replication whilst increase in amino acid sequence lengths within the V3 sub-region may be essential in
immunological recovery. However, bigger longitudinal studies are necessary to substantiate these
findings.