Profiling of Substrate Specificities of 3C-Like Proteases from Group 1, 2a, 2b, and 3 Coronaviruses

Chuck, Chi-Pang; Chow, Hak-Fun; Wan, David Chi-Cheong; Wong, Kam-Bo

A number of coronaviruses (CoVs) have been identified as causative agents of respiratory tract and gastroenteritis diseases in mammals and birds [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11] . Sequence analysis suggests that these coronaviral strains can be classified into three main groups -alphacoronavirus (group 1), betacoronavirus (group 2), and gamacoronavirus (group 3) [12] . The sequence of severe acute respiratory syndrome coronavirus (SARS-CoV), discovered in 2003, was found to be diverse from any existing groups of CoVs. The group 2 CoVs are then further divided into 2a and 2b subgroups, with the original group 2 CoVs assigned to group 2a and SARS-CoV to group 2b [13, 14] . Most of coronaviral strains are group 1 and 2a members. They include the four human coronaviruses (HCoVs) strains, NL63, 229E, OC43 and HKU1, that associate with up to 5% of total respiratory tract disease cases [15, 16] . The most infamous strain in group 3 is infectious bronchitis virus (IBV), which can cause lethal infections in birds [17, 18] .