Evidence for a lineage of virulent bacteriophages that target Campylobacter

Abstract

BackgroundOur understanding of the dynamics of genome stability versus gene flux within bacteriophage lineages is limited. Recently, there has been a renewed interest in the use of bacteriophages as 'therapeutic' agents; a prerequisite for their use in such therapies is a thorough understanding of their genetic complement, genome stability and their ecology to avoid the dissemination or mobilisation of phage or bacterial virulence and toxin genes. Campylobacter, a food-borne pathogen, is one of the organisms for which the use of bacteriophage is being considered to reduce human exposure to this organism.ResultsSequencing and genome analysis was performed for two Campylobacter bacteriophages. The genomes were extremely similar at the nucleotide level (≥ 96%) with most differences accounted for by novel insertion sequences, DNA methylases and an approximately 10 kb contiguous region of metabolic genes that were dissimilar at the sequence level but similar in gene function between the two phages. Both bacteriophages contained a large number of radical S-adenosylmethionine (SAM) genes, presumably involved in boosting host metabolism during infection, as well as evidence that many genes had been acquired from a wide range of bacterial species. Further bacteriophages, from the UK Campylobacter typing set, were screened for the presence of bacteriophage structural genes, DNA methylases, mobile genetic elements and regulatory genes identified from the genome sequences. The results indicate that many of these bacteriophages are related, with 10 out of 15 showing some relationship to the sequenced genomes.ConclusionsTwo large virulent Campylobacter bacteriophages were found to show very high levels of sequence conservation despite separation in time and place of isolation. The bacteriophages show adaptations to their host and possess genes that may enhance Campylobacter metabolism, potentially advantaging both the bacteriophage and its host. Genetic conservation has been shown to extend to other Campylobacter bacteriophages, forming a highly conserved lineage of bacteriophages that predate upon campylobacters and indicating that highly adapted bacteriophage genomes can be stable over prolonged periods of time.

Quo vadis? — MonitoringCampylobacterin Germany

“…[31]). Hence, current research aims to understand the molecular and phenotypic variety of different types of natural bacteriophages [32][33][34][35] in order to rationally design an appropriate cocktail for efficient reduction of Campylobacter in practice.…”

Campylobacter jejuni Group III Phage CP81 Contains Many T4-Like Genes without Belonging to the T4-Type Phage Group: Implications for the Evolution of T4 Phages

“…Thus, CP220 and CPt10 have a considerably larger genome than CP81 and encode proteins not encountered in CP81. Most prominent among them are membrane proteins, transposases, and metabolic enzymes including 12 proteins with S-adenosylmethionine (SAM) domains (49). Conversely, the CP81 genome showed an expansion of one protein family, represented by nine ORFs, that is present only in a single member of group II Campylobacter phages.…”

“…No group I Campylobacter phage has yet been sequenced. Recently, the nucleotide sequences of two group II phages (CP220 and CPt10) have been published (49). These two phages share a DNA sequence identity of 96% and some protein matches with T4-type phages.…”

Phages as Therapeutic Tools to Control Major Foodborne Pathogens: Campylobacter and Salmonella

“…The DNA of most Campylobacter phages is difficult to extract, clone and sequence and is refractory to restriction enzyme digestion, which is probably due to tightly adherent and proteinase K resistant proteins Hammerl et al, 2011;Kropinski et al, 2011;Timms et al, 2010). As a consequence, the genome sequence of only five Campylobacter phages have been reported so far Hammerl et al, 2011;Kropinski et al, 2011;Timms et al, 2010).…”

“…As a consequence, the genome sequence of only five Campylobacter phages have been reported so far Hammerl et al, 2011;Kropinski et al, 2011;Timms et al, 2010). Interestingly, the phage genomes known are all related and also part of the T4 superfamily of phages (Petrov et al, 2010).…”