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).