Genomic analysis of jumbo coliphage fEgEco12

Avian pathogenic Escherichia coli (APEC) infections are associated with major economic losses, cause perihepatitis, pericarditis, septicemia and even systemic infections in the poultry industry. APEC infections have usually been controlled by antibiotics, resulting in an increased prevalence of antibiotic-resistant E. coli. Concerns have been increased that transfer of antibiotic-resistant APEC via the food chain may cause risks for extra-intestinal infection of humans related to zoonotic transfer and increased difficulties in the treatment of human infections caused APEC-related E. coli types. With the occurrence of antibiotic resistance reaching a crisis point, it is important to find alternative treatments for multidrug-resistant infections. The use of phages to control pathogens is a promising therapeutic option for antibiotic replacing, therefore, novel phages specific for APEC were isolated in this study. Phage fEgEco12 was isolated from the hospital sewage water sample during a search for candidates for phage therapy applications against APEC. The phage morphology was studied by transmission electron microscopy, and the host range was analyzed with a Bioscreen C analyser. The phage genomic DNA was isolated, sequenced and annotated. Phage stability, phage adsorption and one step growth curve experiments were carried out to characterize its biological properties. Genomic analysis revealed that fEgEco12 is a lytic jumbo phage with genome size of 374,733 bp encoding 670 predicted genes. No genes associated with lysogeny, bacterial virulence, or antibiotic resistance were identified. The phage had myovirus morphology and a narrow host range. Comparative genomic analysis revealed that fEgEco12 and phage Ecwhy_1 belong to a new species in jumbo phage genus Asteriusvirus. fEgEco12 is a novel jumbo bacteriophage that is considered safe for phage therapy.