ABSTRACT
The infection of the novel coronavirus SARS-CoV-2 have caused more than 150,000 deaths, but no vaccine or specific therapeutic antibody is currently available. SARS-CoV-2 relies on its spike protein, in particular the receptor binding domain (RBD), to bind human cell receptor angiotensin-converting enzyme 2 (ACE2) for viral entry, and thus targeting RBD holds the promise for preventing SARS-CoV-2 infection. In this work, a competitive biopanning strategy of a phage display antibody library was applied to screen blocking antibodies against RBD. High-affinity antibodies were enriched after the first round using a standard panning process in which RBD-His recombinant protein was immobilized as a bait. At the next two rounds, immobilized ACE2-Fc and free RBD-His proteins were mixed with the enriched phage antibodies. Antibodies binding to RBD at epitopes different from ACE2-binding site were captured by the immobilized ACE2-Fc, forming a "sandwich" complex. Only antibodies competed with ACE2 for recognizing RBD at the same or similar epitopes can bind to the free RBD-His in the supernatant and be subsequently separated by the Ni-NTA magnetic beads. Top 1 lead from the competitive biopanning of a synthetic antibody library, Lib AB1, was produced as the full-length IgG1 format. It was proved to competitively block the binding of RBD to ACE2 protein, and potently inhibit SARS-CoV-2 pseudovirus infection of ACE2-overexpressing Hela cells with IC50 values of 12nM. Nevertheless, top 1 lead from the standard biopanning of Lib AB1, can only bind to RBD in vitro but not have the blocking or neutralization activity. Our strategy can efficiently isolate the blocking antibodies of RBD, and it would speed up the discovery of neutralizing antibodies against SARS-CoV-2.
ABSTRACT
Objective To investigate the clinical efficacy of montelukast sodium and procaterol for treating the children with chronic cough and its impact on serum immunoglobulin E(IgE).Methods Eighty cases of children with chronic cough were divided into treatment group and control group by random digits table method with 40 cases each.The control group was given procaterol treatment on the basis of conventional treatment,and the treatment group was added montelukast sodium on the basis of treatment of control group.Treatment course was 1 month.Before and after treatment,the clinical symptoms and signs in the two groups were observed,the serum IgE level was detected,the clinical efficacy was evaluated,and the adverse reaction was observed.Results The total effective rate in the treatment group was 95.0％ (38/40),the control group was 67.5％ (27/40),and the difference was significant (x2 =9.928,P ＜ 0.01).The time of cough mitigation and disappearance in the treatment group was (24.41 ± 8.14) d and (41.27 ± 14.74) d,which was lower than that in the control group [(47.27 ± 15.76) d and (57.78 ±20.64) d],and the difference was significant (t =8.153,4.118,P ＜ 0.05).After treatment,the serum IgE level in the treatment group and control group significantly decreased [(295.27 ± 105.45)μg/L vs.(594.48 ± 198.16)μg/L,(427.78 ± 152.78) μ g/L vs.(567.21 ± 189.07) μ g/L,t =8.430,3.628,P ＜ 0.05],and the difference was significant between them (t =4.515,P ＜0.05).There were no serious adverse reactions in two groups.Conclusions The serum IgE may play an important role in the incidence of children with chronic cough,and montelukast sodium and procaterol for treating the children with chronic cough is safe,effective and worthy of clinical application.
