Abstract Description

Bacillus thuringiensis (Bt) bacterium is a widely distributed bacterium with natural entomo-pesticidal properties, attributed to its production of crystalline and soluble proteins across different growth phases. In addition to Cry and Cyt proteins, Bt synthesizes Vegetative insecticidal protein (Vip) during its vegetative growth phase. Vip3A has demonstrated strong insecticidal activity against a broad spectrum of lepidopteran pests and represents a valuable candidate for bioinsecticide development due to its distinct sequence homology and receptor-binding sites compared to Cry proteins. In this study, an M13 phage display library was employed to identify high-affinity binders against Vip3A protein for potential application in novel biopesticides. Three rounds of biopanning were conducted, followed by ELISA screening and functional bioassays to evaluate the effect of phage-displayed scFv on Spodoptera frugiperda larvae. Progressive enrichment of high-affinity clones was observed, with approximately 90% of third round colonies exhibiting strong binding. Bioassay results indicated that larvae treated with phage-displayed scFv exhibited ~50% body weight compared to controls, while treatment with Vip3A in combination with scFv (1:1 ratio) reduced larval body weight by over 90%. These preliminary findings highlight the potential of phage-displayed antibodies in enhancing Vip3A activity and provide a promising foundation for the development of effective and environmentally safe bioinsecticides