[Development of human antibodies against the Gn protein of severe fever with thrombocytopenia syndrome virus].

To obtain human antibodies against the Gn protein of Severe fever with thrombocytopenia syndrome virus (SFTSV) with phage display technology, this study aimed to screen anti-Gn protein antibodies from an anti-SFTSV Fab human phage display library. Antibody genes were identified by sequence analysis and the specificity of antibodies was confirmed by ELISA. The Fab antibody genes were cloned into the HL51-14 vector and expressed in a mammalian cell expression system. IgG antibodies were then purified by protein A affinity chromatography,and the results were further confirmed by ELISA,IFA,western blotting assays and micro-neutralization tests. The results showed that, after three rounds of panning, there were 390 human Fab antibodies against SFTSV particles, of which 364 were specific for nucleoprotein. Coated with the Gn protein, eight different Fab antibodies specific for Gn protein were obtained after the determination of the subtype and subclass of antibodies by gene sequencing; five of these antibodies were from the Lambda library and three were from the Kappa library. The eight IgG antibodies could specifically bind to Gn protein according to the ELISA, IFA and Western blotting assays. The micro-neutralization test showed that these eight antibodies had no neutralizing activity,but they could still provide a reference for research in human monoclonal antibodies against SFTSV.