Protective effect of Lactococcus lactis NZ9000 secreting Bcl2 against Trichinella spiralis infection in mice

Trichinellosis, a globally distributed zoonosis, threatens both human health and livestock productivity. The limited efficacy of existing anthelmintics underscores the need for innovative strategies to control Trichinella spiralis infection.

A recombinant food-grade Lactococcus lactis strain (NZ-Bcl2) was engineered to secrete the anti-apoptotic protein Bcl2 by fusing the Bcl2 gene to the Usp45 signal peptide. Western blotting confirmed successful expression and secretion. NZ-Bcl2 strains exhibited stable growth, maintained plasmid inheritance over 24 generations without antibiotic pressure, and persisted in the murine intestine for at least seven days. In low-dose infections (150 larvae/mouse), oral administration of NZ-Bcl2 significantly reduced muscle larval burden, mitigated intestinal damage, and alleviated mesenteric lymph node enlargement. These protective effects were associated with downregulation of pro-inflammatory cytokines (IL-1β, TNF-α), upregulation of anti-inflammatory cytokines (IL-10, TGF-β), and increased expression of intestinal barrier markers (claudin-3, MUC-1). Under high-dose challenge (600 larvae/mouse), the protective effects were attenuated.

Recombinant L. lactis secreting Bcl2 confers partial protection against T. spiralis by enhancing mucosal barrier function and modulating host immunity. These findings highlight the potential of engineered probiotics as a novel platform for antiparasitic intervention, offering translational relevance for food safety and zoonotic disease control.