Data Sheet 1_Engineered Lactobacillus casei targets the IgT-pIgR axis to confer mucosal protection against Aeromonas veronii in snakehead (Channa argus).docx

IntroductionAeromonas 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.
MethodsTo 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.
ResultsAnal 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.
DiscussionThis study elucidated a novel engineered-probiotic mucosal vaccination strategy for teleosts, providing a noninvasive, mucosal targeted immunoprophylactic strategy to decrease antibiotic dependency in aquaculture.