passages.id: split_6_test_1558_passage
passages.type: progene_text
passages.text: Overall immunity was assessed by recall skin testing with peptides , gamma interferon ELISA assays of peptide specific cytolytic T cell ( CTL ) stimulated twice with peptide , IL-2 , and IL - 7 over 24 days , and peptide - specific tetramer assays performed before and after vaccination .