Complete Genomic Sequence of Bacteriophage φEcoM-GJ1, a Novel Phage That Has Myovirus Morphology and a Podovirus-Like RNA Polymerase

Abstract

The complete genome of EcoM-GJ1, a lytic phage that attacks porcine enterotoxigenic Escherichia coli of serotype O149:H10:F4, was sequenced and analyzed. The morphology of the phage and the identity of the structural proteins were also determined. The genome consisted of 52,975 bp with a G؉C content of 44% and was terminally redundant and circularly permuted. Seventy-five potential open reading frames (ORFs) were identified and annotated, but only 29 possessed homologs. The proteins of five ORFs showed homology with proteins of phages of the family Myoviridae, nine with proteins of phages of the family Podoviridae, and six with proteins of phages of the family Siphoviridae. ORF 1 encoded a T7-like single-subunit RNA polymerase and was preceded by a putative E. coli 70 -like promoter. Nine putative phage promoters were detected throughout the genome. The genome included a tRNA gene of 95 bp that had a putative 18-bp intron. The phage morphology was typical of phages of the family Myoviridae, with an icosahedral head, a neck, and a long contractile tail with tail fibers. The analysis shows that EcoM-GJ1 is unique, having the morphology of the Myoviridae, a gene for RNA polymerase, which is characteristic of phages of the T7 group of the Podoviridae, and several genes that encode proteins with homology to proteins of phages of the family Siphoviridae.Postweaning diarrhea (PWD) due to enterotoxigenic Escherichia coli (ETEC) is a major problem for the swine industry (2, 17, 36). The ETEC strains that cause this disease typically produce F4 (K88) or F18 fimbriae and belong to a small number of O serogroups, with O149 being dominant worldwide (2,17,19). Strains of this serogroup were responsible for recent exceptionally severe outbreaks of disease in pigs in Ontario (2,26,38). The outbreak strains were almost all O149:H10:F4, whereas O149 strains from earlier periods were all O149: H43:F4 (38). Since multidrug resistance is common among these ETEC strains (2,32,38), and the problem persists despite traditional approaches such as vaccination, antibiotic treatment, feed additives, and management strategies, it was decided to investigate the use of bacteriophages for prophylaxis and therapy.Phage therapy has been effective in the prevention and treatment of experimentally induced diarrhea due to ETEC in neonatal pigs (46) but has never been investigated for PWD. We therefore used a mixture of 10 strains of O149:H10 ETEC from PWD as host strains in order to isolate phages by standard procedures from pig sewage (9). Six phages (EcoM-GJ1 to EcoM-GJ6) were isolated and characterized on the bases of morphology and spectrum of activity against O149:H10:F4 and O149:H43:F4 ETEC strains, strains of other serotypes of ETEC, and the 72 strains of the ECOR collection. The phages were also compared with respect to DNA fragment patterns resulting from digestion with three restriction enzymes. The six phages were similar morphologically and in their restriction enzyme digestion patterns as well as in their ability to lyse all or almost ...

Novel Virulent and Broad-Host-Range Erwinia amylovora Bacteriophages Reveal a High Degree of Mosaicism and a Relationship to Enterobacteriaceae Phages

“…The late gene cluster and the cell lysis cassette are located at the right end. Y2 shows high sequence identities only to ⌽EcoM-GJ1, a phage infecting porcine enterotoxigenic E. coli strains (25). They share a 61.0% overall nucleotide sequence identity and 43 gene products with sequence identities above 20%.…”

Development of Giant Bacteriophage ϕKZ Is Independent of the Host Transcription Apparatus

“…Most known phages do not encode their own RNAP but redirect the host transcription machinery to viral promoters by relying on very strong promoters recognized by host RNAP and/or modifying the host RNAP specificity by phageencoded factors (9,10). Some phages, like T7, N4, Xp10, and EcoM-GJ1, depend on their own single-subunit RNAPs to transcribe a subset of viral genes (11)(12)(13)(14)(15). In these phages, two basic transcriptional strategies have been described.…”

Genomic and Proteomic Characterization of the Broad-Host-Range Salmonella Phage PVP-SE1: Creation of a New Phage Genus

“…Besides ensuring that it has a broad host range and good lytic activity, it is crucial to ensure the absence of lysogeny and potential virulence determinants for therapeutic and prophylaxis purposes (52). Therefore, phage genome sequences should be determined and analyzed to evaluate the phage's safety for therapy (21,32,53). We present here the genomic sequence of PVP-SE1 and show that it is phylogenetically unique and deprived of factors which would preclude its therapeutic use.…”