ABSTRACT
Picornaviruses (PV) and coronaviruses (CoV) are positive-stranded RNA viruses. Pathogens in the family can cause hand, foot and mouth disease, myocarditis, common cold, severe respiratory and intestinal diseases. 3C and 3CL proteases, belonging to cysteine proteases, are required to process polyproteins into mature proteins for viral replication, which plays an important role in viral replication because substrate binding sites are highly conservative and have similar catalytic mechanism. 3C and 3CL proteases are different from protease in the human body, which represents a promising anti-viral drug target. Using 3C and 3CL proteinase structural similarities, broad spectrum protease inhibitors have been found successfully. This review describes recent developments of broad spectrum protease inhibitors targeting on 3C and 3CL proteases, and briefly illustrates the mechanism of the inhibitors, which may benefit to the development of virus therapy.