CD4 and infection: The ‘equivalent’ genotype-1a peptide, which differs by two amino acids, is known to be a DRB1 1101 restricted CD4 T cell target.31 In contrast, in genotype-1 infection, CD4 T cells are known to target a broad range of epitopes within core.23, 24, 34 Viral sequence analysis in 4/5 patients showed no evidence of viral escape supporting previous data in humans,23 and chimpanzees,35 showing that CD4 T cells unlike CD8 T cells rarely exert selection pressure on HCV.