Mice of the resistant H-2b haplotype mount broad CD4+ T cell responses against 9 distinct Friend virus epitopes

To date, only a single Friend virus (FV) peptide recognized by CD4+ T cells in FV-infected mice of the resistant H-2b haplotype has been described. To more thoroughly examine the repertoire of CD4+ T cell responses in H-2b mice infected with this retrovirus, 18mer peptides spanning the FV gag, pol, and env coding regions with 11mer overlaps were synthesized. The peptides were then used to stimulate whole splenocytes and purified CD4+ T cells from FV-infected mice in an IFNγ ELISPOT assay. Nine new CD4+ T cell epitopes were identified, 3 encoded by gag, 1 by pol, and 5 by env. The high resistance of H-2b mice could be related to this very broad CD4+ T cell response against multiple peptides during FV infection.