Design and characterization of a LuxS/AI-2 pathway-informed scorpion venom-derived hybrid peptide IFG-22 for selective inhibition of Gardnerella vaginalis biofilms in bacterial vaginosis

Bacterial vaginosis (BV) is a common vaginal dysbiosis characterized by Gardnerella vaginalis overgrowth, biofilm persistence, inflammation, and disruption of Lactobacillus -dominated microbiota. Conventional antibiotics such as metronidazole are limited by recurrence, incomplete biofilm clearance, and potential disturbance of beneficial commensals. Here, we designed and characterized IFG-22, a LuxS/AI-2 pathway-informed scorpion venom-derived hybrid antimicrobial peptide, to preferentially target G. vaginalis biofilms while preserving vaginal microbial homeostasis. IFG-22 was generated by integrating a LuxS-guided recognition motif with a membrane-active antimicrobial fragment and was optimized through molecular docking and physicochemical screening. IFG-22 showed potent anti- Gardnerella activity, with a minimum inhibitory concentration of 1.2 µg/mL, rapid bactericidal kinetics, and marked inhibition of biofilm formation and persistence. Mechanistic assays indicated that IFG-22 attenuated AI-2-associated signaling output, showed partially DPD/AI-2-rescuable biofilm suppression, selectively interacted with G. vaginalis biofilm lipid components, and induced bacterial membrane disruption. These findings support a combined mechanism in which membrane disruption drives rapid killing, while AI-2-associated signaling attenuation contributes to anti-biofilm activity. IFG-22 displayed weaker activity against representative vaginal commensals than against G. vaginalis and showed preliminary compatibility with vaginal epithelial cells within the effective antimicrobial concentration range. In a murine BV model, IFG-22 reduced G. vaginalis expansion, promoted restoration toward a Lactobacillus -dominated microbiota, and downregulated inflammatory mediator expression in vaginal tissues. IFG-22 also retained substantial peptide integrity and anti- Gardnerella activity under simulated vaginal microenvironmental conditions. Collectively, IFG-22 represents a promising membrane-active and microbiota-sparing peptide candidate for local BV therapy.