Background:  Persistent GB virus C (GBV-C) viremia is associated with slower HIV disease progression and prolonged survival. No studies have investigated the acquisition of GBV-C infection related to HIV seroconversion, or if GBV-C viremia decreases the risk of HIV acquisition in HIV-negative adults.

Methods:  A case-control study nested within the HIV Prevention Trials Network’s Uninfected Participant Cohort (UPC) was performed. Cases were subjects who acquired HIV infection; controls were subjects followed for comparable time who did not acquire HIV. In addition, we evaluated the relationship between GBV-C viremia and HIV viral load set-point. GBV-C viremia prevalence in cases and controls was compared. Among HIV seroconverters, the relationship between GBV-C viremia and median HIV viral load was compared using the two-sample Wilcoxon Rank-Sum test (significance level 0.05). GBV-C viremia was determined using a nested PCR assay.

Results:  We compared 87 HIV seroconverters to 397 randomly selected controls. Overall, 415 (85%) were men, 395 (61%) were Caucasian, and (71%) were men who have sex with men (MSM). The prevalence of GBV-C in the entire group was 13% (n = 62), and there was no association between GBV-C viremia and risk of HIV infection (OR = 1.25, 95% CI 0.59, 2.48; p = 0.5). Among the 66 cases of HIV acquisition, existing GBV-C viremia at the time of HIV acquisition was not associated with lower HIV viral load set-points (GBV-C positive n = 10; median = 4.14 log copies/mL; 25 to 75% IQR 3.9 to 4.8 log copies/mL vs GBV-C negative n = 56; median = 4.36 log copies/mL; 25 to 75% IQR 3.8 to 4.6 log copies/mL; p >0.5). The prevalence of GBV-C viremia increased from 13% pre-HIV seroconversion to 38% post-HIV seroconversion, indicating that a subtantial number of subjects were infected with GBV-C near the time of HIV seroconversion.

Conclusions:  GBV-C viremia is not associated with decreased risk of HIV acquisition among high-risk HIV-negative individuals. Furthermore, we found no association between GBV-C viremia prior to HIV acquisition and lower HIV viral load set-points soon after acquisition of HIV infection. Acquisition of GBV-C viremia at or near the time of HIV seroconversion is common. Thus, GBV-C is unlikely to hold promise with respect to protective HIV vaccine development.  

Keywords: GB Virus C; Acute HIV; Co-infections