The overall evidence in our study showed that the more susceptible line C.B12 birds had a significantly higher number of non-conventional CD8αα αVβ1 and CD4 CD8α double-positive αVβ1 T cells, a lower threshold of activation of cytolytic degranulation in conventional CD8αβ γδ T cells and CD8αβ αVβ1 T cells and a lower expression of immune regulatory genes and a higher type II IFN response after the infection of lung macrophages with H7N1. Here, CD4 is linked to infection.