Cxcr3 and Klrg1 are also downregulated by TEX during chronic viral infection [41] and Cxcr3 is downregulated on T cells after multiple rounds of antigen exposure in vivo [42], suggesting that Cxcr3 loss in PDA is due to persistent TCR signaling. This evidence concerns the gene KLRG1 and Patent ductus arteriosus.