ACE2 and infection: While the SARS-CoV and SARS-CoV-2 viruses use ACE2 as a mediator to enter the cells, MERS-CoV uses dipeptidyl-peptidase 4 (DPP4).(7) Because they are viruses from the same family, some authors have studied whether DPP4 is also involved in the infection mechanism of the new disease.