Strong lymphoproliferative responses to recombinant HCV antigens are detectable in patient C35 despite high GT2b viremia. Lymphocyte proliferation assays (LPAs) with recombinant HCV antigens based on GT1 sequence: core (c22.3), NS4 (c100.3), NS3 + NS4 (c200), NS5, and tetanus toxoid (TT) and PHA as control were performed on fresh PBMCs of patient C35 (“Patients, materials, and methods”) and demonstrate (A) strong responses to multiple antigens despite high untreated viremia. These responses stayed stable over time (data not shown), and did not change (B) after successful antiviral treatment (sustained virologic response) with Peg-interferon and ribavirin for 24 weeks. Patient C35 showed serologic evidence of prior exposure to GT1 virus. Serotyping was performed with the Murex HCV serotyping 1-6 assay (Abbott; “Patients, materials, and methods”).