基于PCV2骨架的PCV3 Cap嵌合病毒反向遗传系统构建及免疫原性评价OA

Porcine circovirus type 3(PCV3)is an emerging pathogen posing a significant threat to the swine industry.However,the isolation and cultivation of native PCV3 are extremely challenging,and obtaining the natural virus remains difficult,which severely hinders research into its pathogenic mechanisms and the development of vaccines.To address this core bottleneck,this study adopted an innova-tive approach to construct a recombinant PCV3 using reverse genetics technology.Given the well-estab-lished reverse genetics system and clear genetic background of PCV2,a chimeric viral genomic clone,pSK-PCV2-3,was successfully constructed by replacing the capsid protein(Cap)gene of a PCV2 infectious clone with the chemically synthesized PCV3 Cap gene via homologous recombination.Following transfection of this plasmid into Vero cells,an infectious chimeric virus,PCV2-3,was successfully rescued.Serial passaging and molecular characterization confirmed that the rescued virus maintained genetic stability in Vero cells and correctly expressed the PCV3 Cap protein.Purified virus particles exhibited a diameter of approximately 17 nm,a morphology consistent with the typical characteristics of circoviruses.Animal studies demonstrated that immunization of BALB/c mice with PCV2-3 induced high levels of PCV3 Cap-specific antibodies and significantly promoted splenic lymphocyte proliferation and the secretion of Th1-type cytokines(IFN-γ,TNF-α).This study reports the first successful establishment of a reverse genetics system for a PCV3 chimeric virus based on the PCV2 backbone,overcoming the technical challenge of obtaining native PCV3 and providing a critical technological platform and candidate material for research into PCV3 pathogenesis and vaccine development.