ACE2 and viral infectious disease: Upon viral infection, there was a substantial reduction in the mRNA levels of DDC (2-fold) and dACE2 (3.5- and 7-fold, at 24 h and 48 h post-infection, respectively), as well as in the ACE2 mRNA levels (6.3- and 17.5-fold at the two time points tested) (Fig 8).