Higher dN/dS ratios in the HCV core gene, but not in the E1/HVR1 gene, are associated with human immunodeficiency virus-associated immunosuppression

Coinfection with HCV and HIV is prevalent among former commercial blood donors in some rural areas in China. Genetic variability of the HCV core and E1/HVR1 was investigated in 23 patients chronically infected with HCV-1b, with or without concomitant HIV infection. Genetic variability in the core sequence was higher under HIV-associated immunocompromised conditions. Both the Shannon entropy values at each nucleotide position and the dN/dS values at each codon were statistically higher in HIV/HCV-coinfected patients with lower CD4+ T cell counts (p-values were <0.0001 and equal to 0.0372, respectively). The more significant difference of dN/dS value occurred in a specific subregion of the core gene that is enriched in CTL/Th epitopes (p = 0.0083). The dN/dS values of full-length core antigen were found to be negatively correlated with the S/CO ratio of plasma anti-HCV antibodies. By contrast, no significant difference in genetic diversity/complexity and dN/dS values in the E1/HVR1 region was found between those two groups. These results suggest that the dN/dS ratio in the core gene, but not in the E1/HVR1 gene, is influenced more by host CD4+ T cell–mediated cellular immunity.