HLA-DRB1 and hepatitis C virus infection: Interestingly, one HLA-DRB1-restricted hepatitis C ICS (identified initially during screening, but not included in the vaccine construct described herein) exhibited extensive human homology and the ability to elicit the response of regulatory T cells within the PBMC population derived from HCV infected, but not non-infected, individuals (Losikoff et al., manuscript submitted).