ABSTRACT
Objective@#To study the construction and humoral immunogenicity of the recombinant plasmids encoding nonstructural proteins(NSs) of severe fever with thrombocytopenia syndrome(SFTS) virus(SFTSV).@*Methods@#Recombinant plasmids encoding NSs gene and optimized NSs gene of SFTSV were constructed by polymerase chain reaction(PCR) and cloned into eukaryotic expression vector pJW4303, which were named pJW4303-NSs and pJW4303-NSs-opt, respectively. Then, the plasmid pJW4303-NSs was tagged with Flag, named pJW4303-NSs-Flag. Meanwhile, Nhe I restrict site and tissue plasminogen activator(tPA) signal sequence were inserted to construct bi-optimized recombinant plasmid named pJW4303-tPA-NSs-opt. All plasmids were identified by sequencing. The transient expression of NSs was confirmed by Western blotting in human embryonic kidney 293T cells. The NSs-specific IgG antibodies in BALB/c mice which were immunized by intramuscular injection with electroporation were examined by enzyme-linked immunosorbent assay(ELISA).@*Results@#The recombinant plasmids pJW4303-NSs, pJW4303-NSs-opt, pJW4303-tPA-NSs-opt and pJW4303-NSs-Flag were successfully constructed. The expression of NSs was confirmed in lysates and supernatants of 293T cells. The NSs-specific IgG responses of all three recombinant plasmids were detected by ELISA in BALB/c mice. It was found that optimized recombinant plasmid pJW4303-NSs-opt elicited higher levels of the NSs-specific IgG than that of pJW4303-NSs in week 6, 8 which induced stronger immune response.@*Conclusions@#The recombinant plasmids encoding SFTSV NSs possess the satisfied immunogenicity. In addition, the plasmid pJW4303-NSs-opt could induce the strongest humoral immune response.