Comparison of Viro-immunological Marker Changes Between HIV-1 and HIV-2-infected Patients in France

Background: HIV-2 is known to be less pathogenic than HIV-1, although the underlying mechanisms are still debated. We compared the changes over time in viro-immunological markers in HIV-1 and HIV-2-infected patients living in France during natural history and after initiation of the first combination antiretroviral therapy (CART).

Method: Patients were included in the ANRS CO3 HIV-1 cohort (N = 6707) or the ANRS CO5 HIV-2 cohort (N = 572). HIV-1-infected patients were matched to HIV-2 patients according to sex, age, HIV transmission group and period of treatment initiation. Changes in markers were estimated using linear mixed models.

Results: Analyses were performed for three groups of patients: those with estimated date of contamination (98 HIV-1 and 49 HIV-2-seroincident patients); untreated seroprevalent patients (320 HIV-1 and 160 HIV-2); and those initiating a first CART (59 HIV-1 and 63 HIV-2). In group 1, CD4 T-cell counts decreased less rapidly in HIV-2 than HIV-1 patients (-9 versus -49 cells/microl per year, P < 10(-4)). Results were similar in group 2. Baseline CD4 cell count at CART initiation was not different according to the type of infection. During the first 2 months of treatment, the CD4 cell count increased by +59 cells/microl per month (CI 34; 84) for HIV-1 and +24 (CI 6; 42) for HIV-2. The plasma viral load drop was threefold more important in HIV-1 patients: -1.56 log10/ml per month versus -0.62 among HIV-2 patients (P < 10(-4)).

Conclusion: Differences between the two infections during natural history are similar to those previously described in Africa. Once treatment is started, response is poorer in HIV-2 than in HIV-1 patients.