Passive Immunization:
Observing that infected individuals with SARS infection have efficient neutralizing antibodies after their recovery, it was postulated that the use of monoclonal antibodies may be efficient in controlling CoV infections after the exposure to the virus(73).
A clinical trial study involving the administration of a group of monoclonal antibodies directed against six specific epitopes in MERS S protein which are responsible for receptor binding and membrane fusion has started(88). Similarly, targeting many S protein epitopes may be a promising strategy to augment the humoral immune response against CoVs infections. The cross-reactivity of monoclonal antibodies directed against SARS RBD is significantly based on the similarity among RBDs of CoVs(89).
These cross-reacting SARS RBD-specific antibodies can be tested for effectiveness in SARS-CoV-2 patients. Hence, comparative studies are needed to compare receptor binding domains of SARS-CoV-2 with those of SARS in order to determine the appropriate antibodies to be investigated clinically(90).
The development of totally human antibodies as human single-chain antibodies or humanized-nanobodies could be possible through technology, these antibodies (transbodies) could traverse the host cell membrane to interrupt the viral replication process through binding to one or more of the viral proteins. Examples of these transbodies are those directed against influenza, hepatitis C virus(HCV), Ebola, and Dengue viruses(91).Therefore, it could be a good option in treating COVID-19 patients with transbodies directed against the SARS-CoV-2 intracellular peptides as papain-like proteases (PLpro), cysteine-like protease (3CLpro) or any other non-structural proteins to inhibit the viral replication machinery safely (92).