Background. Human immunodeficiency virus type 1 (HIV-1) subtype may
influence disease progression. We compared CD4 lymphocyte cell count
levels at seroconversion, decline rates and viral load set point in
individuals infected with different HIV-1 subtypes.
Methods. We used data from the Concerted Action on SeroConversion to
AIDS and Death in Europe (CASCADE) collaboration, restricted to those
infected since 1996, aged >= 15 years, and applied mixed effects models
for CD4 cell count decline and median regression for viral load set
point (mean level 6-24 months from seroconversion).
Results. The analysis included 3364 seroconverters with known HIV-1
subtypes. Compared with subtype B, CD4 at seroconversion was
significantly higher for subtype CRF01 and lower for subtype C.
Subsequent CD4 decline was significantly slower for subtypes A and CRF02
and marginally slower for subtype C compared with B. Mean CD4 loss at 2
years of seroconversion for white men exposed through sex between men,
aged 30-39 years, having seroconverted since 2006, enrolled within 6
months of seroconversion, and without acute infection was 88, 142, 100,
130, 103, and 167 cells/mu L for subtypes A, B, C, CRF01_AE, CRF02_AG,
and G, respectively. In adjusted analysis, median viral load set point
and time to clinical AIDS/death did not differ significantly by subtype,
although all subtypes, except C, tended to have lower levels compared
with B.
Conclusions. HIV-1 subtype significantly influences seroconversion CD4
cell levels and decline rates but not viral load set point. These
findings may be helpful to HIV-positive individuals and their attending
physicians in understanding disease progression
