Identification and characterization of a 3C-like protease from rabbit hemorrhagic disease virus, a calicivirus

Expression studies conducted in vitro and in Escherichia coli led to the identification of a protease from rabbit hemorrhagic disease virus (RHDV). The gene coding for this protease was found to be located in the central part of the genome preceding the putative RNA polymerase gene. It was demonstrated that the protease specifically cuts RHDV polyprotein substrates both in cis and in trans. Site-directed mutagenesis experiments revealed that the RHDV protease closely resembles the 3C proteases of picornaviruses with respect to the amino acids directly involved in the catalytic activity as well as to the role played by histidine as part of the substrate binding pocket.