Elucidating the lytic potential of the isolated phages, PBM-1 & PBM-2 against the Avian Pathogenic Escherichia coli (APEC-O1)

Abstract

Colibacillosis is one of the most catastrophic disease of poultry worldwide, responsible for increased mortality that leads to major economic losses. As antibiotic resistant strains are prevailing, alternative strategies are being suggested to control the infection, one of them is “phage therapy. In post-antibiotic era, phage therapy is a potential alternative treatment as bacteriophages are specific to host cells causing no harm to eukaryotic cells and commensal microflora. In this study; 2 lytic phages, PBM-1 and PBM-2 were isolated from poultry bedding material taken from different sheds of same poultry farm. The isolated phages showed clear plaques on lawn of Avian Pathogenic E. coli O1 (APEC-O1) with no attributes of lysogeny. Transmission electron microscopy revealed that both phages belong to Myoviridae with an icosahedral head and a contractile tail. Host range was examined against 40 clinical pathogenic strains and both phages showed infectivity against 10 APEC strains. PBM-1 and PBM-2 showed a high adsorption rate over 90% and 95% to host bacterium over a short period of time. Stability studies showed that both phages were stable over a wide range of temperature and pH. Bacterial cell lysis assay revealed that both phages can reduce the bacterial growth up-to 6 hours. Latent period of PBM-1 and PBM-2 is 20 and 25 mins having a burst size of 102 and 97 virions per bacterium. Our results indicate that both studied phages are potential candidates for use in phage therapy. Further genomic and proteomic analysis will help to unravel the therapeutic potential of these phages.