To the best of our knowledge, this is the first study to report overlapping between humans and pig genes (CD4, CD8A, CD8B, KLRC2, RMND5A and VPS24) associated with the variation of T-cell populations, further supporting the use of pig as a very reliable biomodel for human infectious diseases, vaccine development and T-cell research (51–53). The gene discussed is CD4; the disease is infectious disease.