Effect of human leukocyte antigen class I and II alleles on hepatitis C viral load among chronic hepatitis C patients in Southern Taiwan

The viral load of hepatitis C virus (HCV) in chronic hepatitis C patients affects clinical outcomes and response to interferon treatment. Various factors may be involved in determining the viral load, including host genetic factors. The aim of this study was to investigate the relationship between HCV viral load and human leukocyte antigen (HLA) class I and class II alleles. One hundred and six HCV RNA positive subjects were enrolled, and viral load was measured. HLA-A, -B, -C, -DR, and -DQ loci were determined by sequence-based genotyping. Univariate analysis indicated that HLA-B^*40 and HLA-C^*07 alleles had significantly higher HCV RNA levels (P<0.05). Patients with the HLA-C^*15 allele exhibited a trend toward a lower HCV viral load (P=0.06). After controlling for confounding factors, multivariate analysis revealed that only HLA-C^*15 allele was identified as a significant determinant for HCV-RNA level (slope=-0.91, 95% CI: -1.58, -0.24; Holm's P<0.01). Patients expressing the HLA-C^*15 allele had significantly lower HCV RNA levels. HCV genotype 1 was significantly associated with high HCV RNA levels (P<0.05 by Mann-Whitney U test). In conclusion, HLA-C^*15 is an important host immunogenetic factor with an inverse association to HCV viral load in CHC patients in Taiwan. HCV genotype 1 is the viral factor that associated with high viral load.