HLA-A and influenza: It is established that T cells show cross-reactivity to unrelated peptide epitopes presented by a single HLA allele—for example, cross-recognition of influenza and Epstein-Barr virus (EBV) peptides with HLA-A*02:01 (13), pathogenic cross-recognition of influenza and self-epitopes (14), and potentially beneficial cross-reactivity between viruses and tumor antigens (15).