Effect of GB virus C on response to antiretroviral therapy in HIV‐infected Brazilians*

Abstract

ObjectivesGB virus C (GBV‐C) infection is associated with delayed mortality in HIV‐infected people in most, but not all, studies. Previous investigations of the effect of GBV‐C viraemia on response to antiretroviral therapy (ART) were inconclusive. To determine the effect of GBV‐C on ART, we retrospectively analysed plasma samples taken from patients in a prospective randomized clinical trial of ART in HIV‐positive Brazilians.MethodsGBV‐C viraemia was characterized by testing stored serum samples from 175 participants by reverse transcriptase–polymerase chain reaction (RT‐PCR). Subjects were randomized to receive indinavir (n=59), zidovudine and lamivudine (n=58), or zidovudine, lamivudine and indinavir (n=58). The effect of GBV‐C viraemia on the average change in HIV viral load and CD4 count following initiation of therapy was evaluated in a multiple regression analysis.ResultsThe prevalence of GBV‐C viraemia was similar to that observed in previous studies (24%). HIV viral load decreased following ART to a significantly greater extent in patients with GBV‐C viraemia (by 0.48 log10 HIV‐1 RNA copies/mL, P=0.009, adjusting for age, ART group, and baseline CD4 count). Although there was no significant difference in change in CD4 count between individuals with and without GBV‐C viraemia overall, CD4 counts were higher following 48 weeks of therapy in GBV‐C viraemic individuals receiving the least potent ART regimen (zidovudine and lamivudine) compared with those without GBV‐C infection.ConclusionsGBV‐C viraemia is associated with an enhanced reduction of HIV viral load in response to ART. In this study of treatment‐naive individuals during 48 weeks of follow up, patients with GBV‐C viraemia had reductions in HIV viral load that were approximately 0.5 log copies/mL greater than those found in patients without GBV‐C viraemia. This is similar to reductions observed with nucleoside reverse transcriptase inhibitors.