Enterotoxigenic Escherichia coli (ETEC) is a global primary pathogenic bacterium causing diarrhoea in human and a wide variety of neonatal animals. Lactococcus lactis as non-pathogenic and food-grade lactic acid bacteria has already been explored as a vector for mucosal vaccine. Here, the current study was undertaken to evaluate the live recombinant L. lactis (rL. lactis) vaccine expressing the trivalent enterotoxin protein STa-LTB-STb and the F5 fimbrial antigen (SLS-F5) with OmpH of Yersinia enterocolitica in protection against ETEC. Western blot confirmed the expression of fusion protein SLS-F5-OmpH in nisin-controlled expression (NICE) system. Mice orally immunized with rL. lactis-SLS-F5-OmpH were observed to produce high levels of mucosal SIgA and serum IgG antibodies, while also inducing increases in the production of CD4⁺ and CD8⁺ T cells, lymphocyte proliferation, and secretion of cytokines. Moreover, orally immunized mice produced complete protection after ETEC challenge. The above results suggested that rL. lactis-SLS-F5-OmpH has the potential as a candidate for oral vaccine against ETEC.

肠毒素性大肠杆菌（ETEC）是导致人类和多种新生动物腹泻的全球主要致病菌。乳酸乳球菌是一种非致病性和食品级乳酸菌，已被用作粘膜疫苗的载体。在这里，目前的研究进行了评估活的重组乳酸乳球菌（R乳酸乳球菌）疫苗与表达的OmpH三价肠毒素蛋白STA-LTB-STB与F5菌毛抗原（SLS-F5）小肠结肠炎耶尔森菌的防范ETEC。Western blot证实融合蛋白SLS-F5-OmpH在乳链菌肽控制表达（NICE）系统中的表达。乳酸乳球菌口服免疫的小鼠观察到-SLS-F5-OmpH产生高水平的粘膜SIgA和血清IgG抗体，同时还诱导CD4 ⁺和CD8 ⁺ T细胞的产生，淋巴细胞增殖和细胞因子分泌增加。此外，口服免疫的小鼠在ETEC攻击后产生了完全的保护。上述结果表明，乳酸乳球菌-SLS-F5-OmpH具有作为针对ETEC的口服疫苗的候选物的潜力。