Broadly effective and safe anti-coronavirus agent is existentially needed. Major protease (3CL) is a highly conserved enzyme of betacoronaviruses. The enzyme plays pivotal role in the virus replication cycle. Thus, it is a good target of a broadly effective anti- agent. In this study, human single-chain antibodies (HuscFvs) of the SARS-CoV-2 3CL were generated using phage display technology. The 3CL-bound phages were used to infect host for the production the 3CL-bound HuscFvs. Computerized simulation was used to guide the selection of the phage infected- clones that produced HuscFvs with the 3CL inhibitory potential. HuscFvs of three phage infected- clones were predicted to form contact interface with residue... More
Broadly effective and safe anti-coronavirus agent is existentially needed. Major protease (3CL) is a highly conserved enzyme of betacoronaviruses. The enzyme plays pivotal role in the virus replication cycle. Thus, it is a good target of a broadly effective anti- agent. In this study, human single-chain antibodies (HuscFvs) of the SARS-CoV-2 3CL were generated using phage display technology. The 3CL-bound phages were used to infect host for the production the 3CL-bound HuscFvs. Computerized simulation was used to guide the selection of the phage infected- clones that produced HuscFvs with the 3CL inhibitory potential. HuscFvs of three phage infected- clones were predicted to form contact interface with residues for 3CL catalytic activity, substrate binding, and homodimerization. These HuscFvs were linked to a cell-penetrating peptide to make them cell-penetrable, i.e., became superantibodies. The superantibodies blocked the 3CL activity in vitro, were not toxic to human cells, traversed across membrane of 3CL-expressing cells to co-localize with the intracellular 3CL and most of all, they inhibited replication of authentic SARS-CoV-2 Wuhan wild type and α, β, δ, and Omicron variants that were tested. The superantibodies should be investigated further towards clinical application as a safe and broadly effective anti- agent.
