Introduction: Aeromonas veronii remains a pervasive aquatic pathogen precipitating catastrophic economic depletion and threats to global food security. Conventional therapeutic modalities are constrained by inadequate stability, prohibitive costs, and biosafety risks.
Methods: To address such challenges, an engineered Lactobacillus casei strain was developed to constitutively express the A. veronii outer membrane protein OmpAI through a tandem promoter system to ensure optimized antigen delivery.
Results: Anal intubation with engineered L. casei in Channa argus stimulated compartmentalized mucosal immunity, evidenced by a six-fold elevation in hindgut IgT transcripts, significant infiltration of IgT+ B cells, and pIgR mediated transcytosis, synchronized with systemic IgM activation. The probiotic treament accelerated pathogen clearance, improved survival rates to 42.9% compared to 12.5% in control group, and reorganized the commensal microbiome through a specific enrichment of beneficial Firmicutes.
Discussion: This study elucidated a novel engineered-probiotic mucosal vaccination strategy for teleosts, providing a noninvasive, mucosal targeted immunoprophylactic strategy to decrease antibiotic dependency in aquaculture.
Keywords: Aeromonas veronii; Channa argus; Lactobacillus casei; immunoglobulin; mucosal immunity.
Copyright © 2026 Gao, Dou, Ma, Ma, Li, Qian, Shan, Sun, Zhang, Zhang, Wang and Zhang.