Journal Article

A novel broad-spectrum lytic phage vB_EcoM_P3322: isolation, characterization, and therapeutic potential against avian pathogenic Escherichia coli

Chen, Mingshuai, Zhang, Wei, Zhang, Mengfei, Xie, Jinxin, Bai, Yixin, Tian, Yuan, Zang, Qirui, Aishan, Gulina, Jin, Wanjing, Huang, Ying, Tong, Panpan, Lan, Xueqin, Su, Zhanqiang, Geng, Mingyang

2025

Overview

The widespread misuse of antibiotics has accelerated the emergence of multidrug-resistant bacterial strains, presenting a major threat to global public health. Bacteriophages (phages), owing to their host-specific lytic activity and self-replicating nature, have emerged as promising alternatives or adjuncts to conventional antibiotic therapies. In this study, a lytic phage targeting avian pathogenic Escherichia coli (APEC) was isolated from farm wastewater. The phage's morphological characteristics, host range, optimal multiplicity of infection (MOI), one-step growth curve, pH stability, thermal stability, chloroform sensitivity, and in vitro antibacterial activity were determined. Subsequently, the therapeutic efficacy of the phage was evaluated in a pigeon model. In this study, we isolated and characterized a lytic phage, designated vB_EcoM_P3322, from farm wastewater targeting APEC. Transmission electron microscopy classified vB_EcoM_P3322 within the Myoviridae family. The phage exhibited broad lytic activity against five Escherichia coliserotypes (O8:H10, O15:H18, O51:H20, O149:H20, and O166:H6). Optimal biological parameters included a multiplicity of infection (MOI) of 1, a latent period of 10 minutes, an 80-minute burst period, and a burst size of 252 PFUs/cell. vB_EcoM_P3322 maintained stable lytic activity across a pH range of 5-9 and temperatures from 4°C to 50°C, although it was sensitive to chloroform. In vitro, the phage effectively suppressed bacterial growth within 6 hours at MOIs of 0.1, 1, and 10. Whole-genome sequencing revealed a 151,674 bp double-stranded DNA genome encoding 279 predicted open reading frames. No virulence factors, toxin genes, antibiotic resistance genes, or lysogeny-related elements were identified, affirming its safety for therapeutic application. Phylogenetic analysis indicated 98.44% nucleotide identity (97% coverage) with phage vB_EcoM_Ro121c4YLVW (GenBank: NC_052654), suggesting a close evolutionary relationship. In a pigeon infection model, vB_EcoM_P3322 treatment significantly improved survival and reduced histopathological damage in the liver and spleen. Metagenomic analysis of duodenal contents revealed a marked reduction (P < 0.01) in E. coli abundance in the treatment group, indicating selective pathogen clearance and modulation of gut microbiota. In summary, vB_EcoM_P3322 displays broad-spectrum lytic activity, robust environmental stability, potent antibacterial efficacy both in vitro and in vivo, and a safe genomic profile. These attributes support its potential as a novel biocontrol agent for managing APEC infections in poultry farming.

• Publisher: Frontiers Media SA,Frontiers Media S.A
• Subject: Animals / Antibacterial activity / Antibiotic resistance / Antibiotics / avian pathogenic Escherichia coli / bacteriophage / Biological control / broad-spectrum / Burst size / Cell size / characteristics / Chloroform / Coliphages - classification / Coliphages - genetics / Coliphages - isolation & purification / Coliphages - physiology / Coliphages - ultrastructure / Columbidae - microbiology / Diarrhea / Drug resistance / E coli / Escherichia coli / Escherichia coli - pathogenicity / Escherichia coli - virology / Escherichia coli Infections - microbiology / Escherichia coli Infections - therapy / Escherichia coli Infections - veterinary / Experiments / Genome, Viral / Genomes / Genomics / Host range / Host Specificity / Hydrogen-Ion Concentration / Infections / Intestinal microflora / Latent period / Lysogeny / Metagenomics / Morphology / Multidrug resistance / multidrug-resistant / Multiplicity of infection / Myoviridae - classification / Myoviridae - genetics / Myoviridae - isolation & purification / Myoviridae - physiology / Myoviridae - ultrastructure / Open reading frames / Phage Therapy - methods / Phages / Phylogenetics / Phylogeny / Physical characteristics / Poultry / Poultry Diseases - microbiology / Poultry Diseases - therapy / Poultry farming / Public health / Thermal stability / Transmission electron microscopy / Virulence / Virulence factors / Wastewater / Wastewater - virology / Whole genome sequencing