SARS-CoV (SARS coronavirus) is the virus that causes severe acute respiratory syndrome (SARS). Coronaviruses encode papain-like proteases (PLpro) that are often multifunctional enzymes with protease activity to process the viral replicase polyprotein and deubiquitinating (DUB)/deISGylating activity, which is hypothesized to modify the innate immune response to infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19) is the epidemic and the challenge. COVID-19 is similar to the CoV circulating in Rhinolophus, with a 98.7% nucleotide similarity to the partial RNA dependent RNA polymerase gene of the bat coronavirus strain BtCoV/4991 and 87.9% nucleotide similarity to bat coronavirus strain bat-SL-CoVZC45 and bat-SL-CoVZXC21. Remdesivir and Chloroquine are promising agents against COVID-19.