Studies have found that the genetic divergence between HIV type 1 group O (HIV-1/O) and group M (HIV-1/M) has an impact on both virologic monitoring and drug susceptibility. However, less is known about its impact on therapeutic outcomes. The authors were interested in whether responses to antiretroviral therapy (ART) were similar between the groups despite strain divergence. They performed an open non-randomised study comparing the immunological, virological and clinical responses to two nucleoside reverse transcriptase inhibitors plus one ritonavir-boosted protease inhibitor ART, in naive and paired HIV-1/O- versus HIV-1/M-infected patients (ratio 1:2), matched on sex, age, CD4+ T cell count, haemoglobin level and HBsAg status. The primary endpoint was the proportion of patients with undetectable plasma viral load (VL, threshold 60 cp/mL) at week 48 (W48). Secondary endpoints were the proportion of patients with undetectable VL at W24 and W96, and CD4+ evolution between baseline and W24, W48 and W96. The authors recruited 47 HIV-1/O and 94 HIV-1/M patients. The mean VLs at baseline were significantly lower, by 1 log, for HIV-1/O versus HIV-1/M patients. At W48, there was no significant difference between populations with undetectable VL, at 80.9% of HIV-1/O versus 75.5% of HIV-1/M patients. Differences at W24 and W96 were also not significant. A difference in CD4+ T cell gain was seen, with more CD4+ T cells in HIV-1/M at W48 and W96, but this was not significant when adjusted by matched criteria and VL at baseline. Therefore there are similar immuno-virological and clinical responses between HIV-1/O and HIV-1/M patients, suggesting that genetic divergence does not impact therapeutic outcomes. However, there was significantly lower baseline replication occurring in HIV-1/O patients.
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