No association between GB virus-C viremia and virological or immunological failure after starting initial antiretroviral therapy.
BACKGROUND
Co-infection with GBV-C ('Hepatitis G' virus) appears to be associated with slower disease progression in HIV-infected, untreated individuals. We wished to determine whether detection of GBV-C RNA was associated with differential response to HIV therapy in a population-based cohort of 461 individuals initiating antiretroviral therapy between June 1996 and August 1998, in British Columbia, Canada.


METHODS
The presence of GBV-C RNA in plasma was identified by nested RT-PCR, using detection of HIV RNA as a positive control. Time to virological success [achieving HIV plasma viral load (pVL) < or = 500 copies/ml], virological failure (subsequent confirmed pVL > 500 copies/ml) and immunological failure (confirmed CD4 cell count below baseline) were assessed by Kaplan-Meier methods and Cox proportional hazard regression.


RESULTS
Of the 441 individuals for whom results were available, 90 (20.4%) had detectable plasma GBV-C RNA. GBV-C RNA was significantly associated with a lower HIV pVL at baseline (P = 0.004). In univariate and multivariate Cox models, GBV-C RNA positive and negative individuals did not differ with respect to time to virological success [risk ratio (RR), 0.98; 95% confidence interval (CI), 0.75-1.27], time to virological failure (RR, 1.10; 95% CI, 0.74-1.65), or time to immunological failure (RR, 1.09; 95% CI, 0.73-1.63). There was no correlation between detection of GBV-C RNA and mutations in the human chemokine receptors CCR5 and CX CR1, or HIV viral tropism as predicted by the HIV envelope sequence (P > 0.1).


CONCLUSIONS
GBV-C viremia is relatively common in individuals seeking treatment for HIV infection; however, it does not appear to have any effect on initial antiretroviral therapy response.
D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use; D023241:Antiretroviral Therapy, Highly Active; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D005260:Female; D018178:Flaviviridae Infections / Q000150:complications* / Q000821:virology; D029407:GB virus C; D006678:HIV / Q000254:growth & development / Q000302:isolation & purification; D015658:HIV Infections / Q000150:complications / Q000188:drug therapy* / Q000276:immunology / Q000821:virology*; D006525:Hepatitis, Viral, Human / Q000150:complications*; D006801:Humans; D008297:Male; D010949:Plasma; D016016:Proportional Hazards Models; D012367:RNA, Viral / Q000097:blood / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019562:Viral Load; D014766:Viremia / Q000150:complications* / Q000821:virology
D019380:Anti-HIV Agents; D012367:RNA, Viral