Prevalence of GB virus type C viraemia in MSM with or without HIV-1 infection in Beijing, China

Abstract

GB virus C (GBV-C) is frequently identified in patients co-infected with human immunodeficiency virus type 1 (HIV-1) due to the similar transmission routes. However, it remains unclear how these two viruses interact with each other and how one virus affects the replication of the other in the human body. In this study, we performed a case-control study to determine whether GBV-C viraemia could prevent the acquisition of HIV-1 infection, and a cohort study to determine the prevalence, genotypic characteristics and incidence of GBV-C infection in men who have sex with men (MSM) populations in Beijing, China. The prevalence of GBV-C infection in HIV-1-negative subjects was similar to that in HIV-1-positive subjects. Before HIV-1 acquisition, the prevalence of GBV-C was 17·7%, which increased to 27·2% at the acute stage and to 34% at the chronic stage. Genotype 3 was the major genotype of GBV-C in both groups. A significantly positive correlation was observed between the CD4+ T-cell counts and GBV-C viral loads at the acute stage of HIV infection. At the chronic stage (12 months later), this correlation was no longer significant, although it was still positive. Overall, this study demonstrated that pre-existing GBV-C viraemia could not prevent the acquisition of HIV-1 infection and transmission of HIV-1 significantly increased the prevalence of GBV-C viraemia.

Fig. 1.

The occurrence of GBV-C viraemia in subjects at different stages of HIV infection (n = 99) and HIV-negative subjects (n = 175). The x-axis represents the time during which the samples were collected. The y-axis represents the percentage of GBV-C viraemia. P values represent the statistical analysis between each comparison as shown in the figure. Compared by Pearson's χ² test, the significance level was set at 0·05. Visit 1: before HIV infection; visit 2: near HIV infection; visit 3: 12 months post-HIV infection.

Fig. 2.

Phylogenetic tree of 34 GBV-C strains from 34 HIV-infected Chinese MSM subjects (indicated by pt. prefix) based on the sequences of the 5′-UTR gene (300 bp). The phylogenetic tree was constructed by the neighbour-joining method and the evolutionary distances were computed using the maximum composite likelihood method of Mega software (version 5.0). Reference strains of genotypes 1 (U36380), 2 (U44402 and AF081782 from China), 3 (D90601) and 5 (AY949711) were obtained from GenBank. The scale bar represents 0·5% genetic distance (0·005 substitution per site).

Fig. 3.

Phylogenetic tree of 22 GBV-C strains from 22 HIV-1-negative MSM subjects (indicated by NG prefix) based on the sequences of the 5′-UTR gene (300 bp). The phylogenetic tree was constructed by the neighbour-joining method and the evolutionary distances were computed using the maximum composite likelihood method of Mega software (version 5.0). Reference strains of genotypes 1 (U36380), 2 (U44402 and AF081782 from China), 3 (D90601) and 5 (AY949711) were obtained from GenBank. The scale bar represents 0·5% genetic distance (0·005 substitution per site).

Fig. 4.

Comparison of the GBV-C viral loads at the acute and chronic stages of HIV infection in HIV-1-positive subjects (n = 26, one case started ART 3 months after acquiring HIV-1 and was excluded from the analysis.). The x-axis represents the stage of HIV infection, ‘Early’ indicates the acute stage of HIV infection and ‘Late’ indicates the chronic stage of HIV infection. The y-axis represents the GBV-C viral loads (log copies/ml). Evaluated by paired Student's t test; significance level was set at 0·05.

Fig. 5.

Correlation between GBV-C viral loads and CD4⁺ T-cell counts at the acute stage of HIV-1 infection in ART-naive Chinese MSM subjects (n = 27). The x-axis represents the GBV-C viral loads (log copies/ml). The y-axis represents the CD4 cell counts (cells/mm³). The GBV-C viral loads showed a significant positive correlation (r = 0·42, P = 0·03) with the CD4⁺ T-cell counts. The significance level was set at 0·05 in the linear regression analysis.

Fig. 6.

Correlation between GBV-C viral loads and the CD4⁺ T-cell counts at the chronic stage (12 months post-HIV-1 acquisition) of HIV-1 infection in Chinese MSM subjects (n = 26, one case started ART 3 months after acquiring HIV-1 and was excluded from the analysis). The correlation was still positive but no longer significant (r = 0·09, P = 0·67). The x-axis represents the GBV-C viral loads (log copies/ml). The y-axis represents the CD4 cell counts (cells/mm³). The significance level was set at 0·05 in the linear regression analysis.