GB virus C coinfection and HIV-1 disease progression: The Amsterdam Cohort Study.

BACKGROUND The effect that GB virus C (GBV-C) coinfection has on human immunodeficiency virus type 1 (HIV-1) disease progression is controversial and therefore was studied in 326 homosexual men from the prospective Amsterdam Cohort Studies who had an accurately estimated date of HIV-1 seroconversion and were followed up for a median period of 8 years. METHODS A first plasma sample, obtained shortly after HIV-1 seroconversion, and a last plasma sample, obtained before 1996, were tested for GBV-C RNA and envelope protein-2 antibodies. The effect that GBV-C has on HIV-1 disease progression was studied by use of time-dependent Cox proportional-hazards models with adjustment for baseline variables and time-updated HIV-1 RNA and CD4(+) cell count. RESULTS Men who lost GBV-C RNA between collection of the first sample and collection of the last sample had a nearly 3-fold-higher risk of HIV-1 disease progression than did men who had never had GBV-C RNA. This effect became much smaller after adjustment for time-updated CD4(+) cell count. CONCLUSION Rather than a positive effect of GBV-C RNA presence, a negative effect of GBV-C RNA loss on HIV-1 disease progression was found, which disappeared after adjustment for time-updated CD4(+) cell count. We therefore hypothesize that GBV-C RNA persistence depends on the presence of a sufficient number of CD4(+) cells--and that the CD4(+) cell decrease associated with HIV-1 disease progression is a cause, not a consequence, of GBV-C RNA loss.