This study found that 25 out of 75 peptides were potential T cell epitopes in the H5 AIV NP in chickens of the four haplotypes. An analysis of previous results showed that some of those peptides have been identified as T cell epitopes in humans. There is evidence that NP 91-99 (KTGGPIYKR), NP 361-375 (RGVQIAS-NENMETME), and NP 174-184 (RRSGAAGAAVK), which are derived from the H3N2, H3N2, and H1N1, respectively, are T cell epitopes, with MHC restriction alleles of HLA-A68, H-2Db, and HLA-B27, respectively [39] . Of these peptides, NP 89-97 (PKKTGGPIY) and NP 362-369 (GVQIASNE) are completely conserved in all influenza virus strains, while NP 179-186 (AGAAVKGV) is relatively conserved. Some potential epitopes were also shared by several haplotypes. Chickens used for meat and egg production are always heterozygotes, so the identification of these shared T cell epitopes will facilitate the development of broad-spectrum protective vaccines for chickens. Furthermore, epitopes shared by birds and humans are of great importance in the design of rational vaccines for protecting humans and birds from AIV infection.