ENTPD1 and cytomegalovirus infection: The results revealed that the transcript levels of ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD1; related to purinergic metabolism) were up-regulated at week 3 (p < 0.05) and week 4 (p < 0.01) after CMV infection and then declined to the level comparable to the control rats at week 6.