Furthermore, although both rMDV-infected groups showed increases in CD8α+ T and γδ T cells during the early phase of infection, the proportions of CD8α+ T and CD8α+ γδ T cells—likely responding to MDV-infected cells—gradually declined during the late phase in rRB-1B_Meq71/77-infected chickens, returning to levels comparable to those in the control group. This evidence concerns the gene CD8A and infection.