5.3.3 Monoclonal or polyclonal antibodies
Monoclonal or polyclonal antibodies have been recommended as tools for
preventing and treating viral infections. Considering the relatively
high RBD in SARS-CoV-2, the cross-reactivity of anti-SARS-CoV antibodies
with the COVID-19 S protein was evaluated. Tian et al. determined the
potent binding of S protein via a SARS coronavirus-specific human mAb
CR3022 (Tian et al., 2020). Unfortunately, other SARS-CoV RBD directed
mAbs (i.e., 230, m396, and 80R) cannot bind to the COVID-19 RBD (Wrapp
et al., 2020). In this respect, CR3022 may be a promising therapeutic
candidate, either alone or in combination with other neutralizing mAbs,
for the therapy of COVID-19 disease. In addition, tocilizumab is a
monoclonal antibody for the therapy of RA exacerbation. It was designed
to suppress the binding of IL-6 to its receptors, hence mitigating
cytokine release syndrome. At present, it is also being trailed for the
COVID-19 therapy (Jean et al., 2020).
Besides, most patients with severe COVID-19 suffered a lot from the
cytokine storm (Figure 5) (Xu et al., 2020). So, neutralizing antibodies
against other pro-inflammatory cytokines may be another promising
strategy to dampen the inflammatory responses, thus responding well to
treat the COVID-19. In a clinical trial conducted in Anhui, China, IL-6
receptor-targeted mAb tocilizumab was utilized to treat 21 patients with
severe COVID-19. Clinical data showed quick fever control and improved
respiratory function (Cao, 2020). Overall, the development of
COVID-19-specific antibodies takes a long time, meaning the difficulty
in applying antibodies for neoteric pathogens to clinical practice in a
brief period.