KIR3DL1 and chronic hepatitis C virus infection: Frequency of IL28B genotype, KIR3DL1/HLA-Bw4, and KIR2DL2/HLA-C1 combinations in 56 patients with a sustained virological response (SVR) and 59 patients with a non-SVR to pegylated interferon and ribavirin therapy of chronic hepatitis C.