Construction and activity of respiratory syncytial virus nanobodies
Objective To screen nanobodies(Nbs)against respiratory syncytial virus(RSV)by immunizing llama and phage library construction,and to evaluate their binding activity and neutralizing ability.Methods Two llamas were immunized with RSV recombinant F protein to construct phage library,and the FR and CDR sequences of Nbs were screened.Three strains of RSV Nbs were constructed by sequence recombination.After purification by Ni-NTA affinity chroma-tography,the binding activity of the Nbs was detected by ELISA,and the neutralizing activity was evaluated by using RSV A2 strain.Results The three Nbs BF-42,BF-46 and Fh-24 had the relative molecular mass of about 17 000,with the purity of about 95％after purification.BF-42,BF-46 at the concentration of 0.16 μg/mL and Fh-24 at the concentration of 32 ng/mL still exhibited binding activity,and the binding ability of the three was in a dose-dependent manner.At a concentration of 450 μg/mL,all the three Nbs protected 50％of Hep2 cells from virus infection,and 50％cytopathic effect(CPE)appeared,which effectively neutralized viruses.Conclusion The three Nbs constructed in this study have high binding activity and a certain neutralizing ability,which lays a foundation of the application of RSV Nbs.
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