Establishment of a reverse genetics system for feline panleukopenia virus and feasibility study of a live vector vaccine.

A reverse genetics system for the feline panleukopenia virus (FPV) strain JL2280 was successfully established in this study. By optimizing the cloning strategy for the terminal hairpin structures, a full-length infectious clone, pFPV, harboring a KpnI genetic marker was constructed. The recombinant virus (rFPV) was successfully rescued in CRFK cells and exhibited replication kinetics, pathogenicity, and morphological characteristics comparable to those of the wild-type virus.To evaluate the potential of FPV as a live vector, a recombinant virus expressing enhanced green fluorescent protein (EGFP), designated rFPV-EGFP, was generated by inserting a P2A-EGFP cassette downstream of the NS1 gene. The rFPV-EGFP virus mediated efficient EGFP expression in infected cells; however, the fluorescence intensity gradually diminished with serial passages.The reverse genetics platform developed herein provides a valuable tool for investigating the genomic functions, pathogenic mechanisms, and evolution of FPV. Furthermore, the successful rescue of rFPV-EGFP demonstrates the preliminary feasibility of FPV as a live vector for foreign gene expression. Nevertheless, strategies such as optimizing insertion sites or modifying the viral backbone are required to enhance the stability of exogenous protein expression. This study lays the groundwork for the development of novel FPV-based genetically engineered vaccines and antiviral therapeutics.