Lactic acid bacteria that activate immune gene expression in the Caenorhabditis elegans can antagonize the Campylobacter jejuni infection in nematodes, chickens and mice

Abstract Background Campylobacter jejuni is the major microbacillary pathogen responsible for human coloenteritis. Lactic acid bacteria have been shown to protect against Campylobacter infection. But LAB that showed a good ability to inhibit the growth of C. jejuni in vitro are less effective in antagonising C. jejuni in animals and animal models have the disadvantages of high cost, a long cycle, cumbersome operation and insignificant immune response indicators. Caenorhabditis elegans is increasingly used to screen probiotics for anti-pathogenic property. However, no research on the use of C. elegans to screen for probiotic candidates antagonistic to C. jejuni has been conducted to date. Results This study established a Caenorhabditis elegans life-span model enabling preselection of lactic acid bacteria to counter Campylobacter jejuni infection. A potential protective mechanism of the LAB was identified. 9 strains of distinct LAB species offered the high level of protection for Caenorhabditis elegans. Many of the LAB strains with a high protection rate reduced Campylobacter jejuni load in nematodes. The transcription of antibacterial peptide genes, MAPK and Daf-16 signalling pathway related genes was elevated by the LAB isolates with a high protection rate. The reliability of the life-span model of Caenorhabditis elegans was verified using Campylobacter jejuni -infected mice and chicken model respectively. Conclusions These results showed that LAB vary in their ability to protect Caenorhabditis elegans against Campylobacter jejuni, and Caenorhabditis elegans provides a reliable model enabling researchers to screen for LAB antagonistic to Campylobacter jejuni on a large scale.