Abstract

Enterotoxigenic Escherichia coli (ETEC) proliferation in the intestine of piglets after weaning has a great cost to the swine industry. The implementation of restrictions on the use of antibiotics to mitigate bacterial resistance demands new strategies to tackle this pathogen. As bacterial predators, bacteriophages (phages) are being widely explored and its use in veterinary medicine is a step forward. In this work, the efficacy of the T4-like Myoviridae phage vB_EcoM_FJ1 on reducing an ETEC O9:H9 (Sta, F5/F41) load was assessed on an intestinal epithelial cell line (IPEC-1) culture of neonatal pigs.  The cultured cells were infected 2 h prior phage treatment. Preliminary assays on 96-well plates indicated encouraging results 6 h after vB_EcoM_FJ1 action, being the average cell reduction of 2.9 CFU.cm-2. This tendency was still observed 24 h after treatment (less 1.7 CFU.cm-2 comparatively to the non-treated group). The subsequent culture and infection in 12-well plates also provided bacterial reduction after 6h. The impact on the use of phage in epithelial cells was also investigated using the lactate dehydrogenase assay, and suggested vB_EcoM_FJ1 to have a protective effect on IPEC-1 cells by targeting the pathogenic ETEC. The behavior of the pigs’ serum complement system towards the emerging bacteriophage-insensitive mutant isolated after treatment was similar to their wild type pair. Overall, vB_EcoM_FJ1 is presented here as a potential tool to fight against ETEC infections in piglets. Yet, additional assays on transwells culture models will more closely mimic in vivo conditions, providing solid data to support   phages relevance in ETEC control.

Keywords

Neonatal pigs; Epithelial cells