-
Microbial Genomics Nov 2021The human zoonotic pathogen O157:H7 is defined by its extensive prophage repertoire including those that encode Shiga toxin, the factor responsible for inducing...
The human zoonotic pathogen O157:H7 is defined by its extensive prophage repertoire including those that encode Shiga toxin, the factor responsible for inducing life-threatening pathology in humans. As well as introducing genes that can contribute to the virulence of a strain, prophage can enable the generation of large-chromosomal rearrangements (LCRs) by homologous recombination. This work examines the types and frequencies of LCRs across the major lineages of the O157:H7 serotype. We demonstrate that LCRs are a major source of genomic variation across all lineages of O157:H7 and by using both optical mapping and Oxford Nanopore long-read sequencing prove that LCRs are generated in laboratory cultures started from a single colony and that these variants can be recovered from colonized cattle. LCRs are biased towards the terminus region of the genome and are bounded by specific prophages that share large regions of sequence homology associated with the recombinational activity. RNA transcriptional profiling and phenotyping of specific structural variants indicated that important virulence phenotypes such as Shiga-toxin production, type-3 secretion and motility can be affected by LCRs. In summary, O157:H7 has acquired multiple prophage regions over time that act to continually produce structural variants of the genome. These findings raise important questions about the significance of this prophage-mediated genome contingency to enhance adaptability between environments.
Topics: Animals; Cattle; Escherichia coli O157; Genomic Structural Variation; Prophages; Shiga Toxin; Shiga Toxin 2
PubMed: 34751643
DOI: 10.1099/mgen.0.000682 -
Helicobacter Apr 2021Helicobacter pylori is a human gastric carcinogen that is highly prevalent in Latin American. The prophages of H. pylori show a structured population and contribute to...
BACKGROUND
Helicobacter pylori is a human gastric carcinogen that is highly prevalent in Latin American. The prophages of H. pylori show a structured population and contribute to the diversity of this bacterium. However, H. pylori prophages present in American strains have not been described to date. In this study, we identified, characterized, and present the phylogenetic analysis of the prophages present in Colombian H. pylori strains.
METHODS
To characterize Colombian H. pylori strains and their prophages, a Multilocus Sequences Typing (MLST) and a Prophage Sequences Typing (PST), using the integrase and holin genes, were performed. Furthermore, five Colombian H. pylori had their full genome sequenced, and six Colombian H.pylori retrieved from databases, allowing to determine the prophage complete genome and insertion site.
RESULTS
The integrase gene frequency was 12.6% (27/213), while both integrase and holin genes were present in 4.2% (9/213) of the samples analyzed. The PST analysis showed that Colombian prophages belong to different populations, including hpSWEurope, hpNEurope, hpAfrica1, and a new population, named hpColombia. The MLST analysis classified most of the Colombia strains in the hpEurope population.
CONCLUSIONS
The new H. pylori prophage population revealed that Colombian prophages follow a unique evolutionary trajectory, contributing to bacterial diversity. The global H. pylori prophage phylogeny highlighted five phylogenetic groups, one more than previously reported. After the arrival of Europeans, the Colombian H. pylori bacteria and their prophages formed an independent evolutionary line to adapt to the new environment and new human hosts.
Topics: Colombia; Genome, Bacterial; Helicobacter Infections; Helicobacter pylori; Humans; Multilocus Sequence Typing; Phylogeny; Prophages; United States
PubMed: 33400833
DOI: 10.1111/hel.12779 -
BMC Genomics Oct 2022Ralstonia solanacearum species complex (RSSC) strains are destructive plant pathogenic bacteria and the causative agents of bacterial wilt disease, infecting over 200...
BACKGROUND
Ralstonia solanacearum species complex (RSSC) strains are destructive plant pathogenic bacteria and the causative agents of bacterial wilt disease, infecting over 200 plant species worldwide. In addition to chromosomal genes, their virulence is mediated by mobile genetic elements including integrated DNA of bacteriophages, i.e., prophages, which may carry fitness-associated auxiliary genes or modulate host gene expression. Although experimental studies have characterised several prophages that shape RSSC virulence, the global diversity, distribution, and wider functional gene content of RSSC prophages are unknown. In this study, prophages were identified in a diverse collection of 192 RSSC draft genome assemblies originating from six continents.
RESULTS
Prophages were identified bioinformatically and their diversity investigated using genetic distance measures, gene content, GC, and total length. Prophage distributions were characterised using metadata on RSSC strain geographic origin and lineage classification (phylotypes), and their functional gene content was assessed by identifying putative prophage-encoded auxiliary genes. In total, 313 intact prophages were identified, forming ten genetically distinct clusters. These included six prophage clusters with similarity to the Inoviridae, Myoviridae, and Siphoviridae phage families, and four uncharacterised clusters, possibly representing novel, previously undescribed phages. The prophages had broad geographical distributions, being present across multiple continents. However, they were generally host phylogenetic lineage-specific, and overall, prophage diversity was proportional to the genetic diversity of their hosts. The prophages contained many auxiliary genes involved in metabolism and virulence of both phage and bacteria.
CONCLUSIONS
Our results show that while RSSC prophages are highly diverse globally, they make lineage-specific contributions to the RSSC accessory genome, which could have resulted from shared coevolutionary history.
Topics: Bacteriophages; Humans; Phylogeny; Prophages; Ralstonia solanacearum; Virulence
PubMed: 36199029
DOI: 10.1186/s12864-022-08909-7 -
Viruses Sep 2022Bacterial infections of livestock threaten the sustainability of agriculture and public health through production losses and contamination of food products. While... (Review)
Review
Bacterial infections of livestock threaten the sustainability of agriculture and public health through production losses and contamination of food products. While prophylactic and therapeutic application of antibiotics has been successful in managing such infections, the evolution and spread of antibiotic-resistant strains along the food chain and in the environment necessitates the development of alternative or adjunct preventive and/or therapeutic strategies. Additionally, the growing consumer preference for "greener" antibiotic-free food products has reinforced the need for novel and safer approaches to controlling bacterial infections. The use of bacteriophages (phages), which can target and kill bacteria, are increasingly considered as a suitable measure to reduce bacterial infections and contamination in the food industry. This review primarily elaborates on the recent veterinary applications of phages and discusses their merits and limitations. Furthermore, using as a model, we describe the prevalence of prophages and the anti-viral defence arsenal in the genome of the pathogen as a means to define the genetic building blocks that are available for the (synthetic) development of phage-based treatments. The data and approach described herein may provide a framework for the development of therapeutics against an array of bacterial pathogens.
Topics: Anti-Bacterial Agents; Bacteria; Bacterial Infections; Bacteriophages; Farms; Humans; Prophages; Streptococcus suis
PubMed: 36146802
DOI: 10.3390/v14091996 -
BioEssays : News and Reviews in... Aug 2023How much bacterial evolution occurs in our intestines and which factors control it are currently burning questions. The formation of new ecotypes, some of which capable...
How much bacterial evolution occurs in our intestines and which factors control it are currently burning questions. The formation of new ecotypes, some of which capable of coexisting for long periods of time, is highly likely in our guts. Horizontal gene transfer driven by temperate phages that can perform lysogeny is also widespread in mammalian intestines. Yet, the roles of mutation and especially lysogeny as key drivers of gut bacterial adaptation remain poorly understood. The mammalian gut contains hundreds of bacterial species, each with many strains and ecotypes, whose abundance varies along the lifetime of a host. A continuous high input of mutations and horizontal gene transfer events mediated by temperate phages drives that diversity. Future experiments to study the interaction between mutations that cause adaptation in microbiomes and lysogenic events with different costs and benefits will be key to understand the dynamic microbiomes of mammals. Also see the video abstract here: https://youtu.be/Zjqsiyb5Pk0.
Topics: Animals; Prophages; Gastrointestinal Microbiome; Domestication; Ecotype; Lysogeny; Bacteriophages; Bacteria; Mammals
PubMed: 37353919
DOI: 10.1002/bies.202300063 -
Nature May 2020The gut of healthy human neonates is usually devoid of viruses at birth, but quickly becomes colonized, which-in some cases-leads to gastrointestinal disorders. Here we...
The gut of healthy human neonates is usually devoid of viruses at birth, but quickly becomes colonized, which-in some cases-leads to gastrointestinal disorders. Here we show that the assembly of the viral community in neonates takes place in distinct steps. Fluorescent staining of virus-like particles purified from infant meconium or early stool samples shows few or no particles, but by one month of life particle numbers increase to 10 per gram, and these numbers seem to persist throughout life. We investigated the origin of these viral populations using shotgun metagenomic sequencing of virus-enriched preparations and whole microbial communities, followed by targeted microbiological analyses. Results indicate that, early after birth, pioneer bacteria colonize the infant gut and by one month prophages induced from these bacteria provide the predominant population of virus-like particles. By four months of life, identifiable viruses that replicate in human cells become more prominent. Multiple human viruses were more abundant in stool samples from babies who were exclusively fed on formula milk compared with those fed partially or fully on breast milk, paralleling reports that breast milk can be protective against viral infections. Bacteriophage populations also differed depending on whether or not the infant was breastfed. We show that the colonization of the infant gut is stepwise, first mainly by temperate bacteriophages induced from pioneer bacteria, and later by viruses that replicate in human cells; this second phase is modulated by breastfeeding.
Topics: Adult; Bacteriolysis; Bacteriophages; Breast Feeding; Feces; Female; Gastrointestinal Microbiome; Gastrointestinal Tract; Humans; Infant; Infant, Newborn; Lysogeny; Male; Meconium; Prophages; Viruses
PubMed: 32461640
DOI: 10.1038/s41586-020-2192-1 -
Nature Communications Feb 2024Bacteria have evolved diverse antiviral defence mechanisms to protect themselves against phage infection. Phages integrated into bacterial chromosomes, known as...
Bacteria have evolved diverse antiviral defence mechanisms to protect themselves against phage infection. Phages integrated into bacterial chromosomes, known as prophages, also encode defences that protect the bacterial hosts in which they reside. Here, we identify a type of anti-phage defence that interferes with the virion assembly pathway of invading phages. The protein that mediates this defence, which we call Tab (for 'Tail assembly blocker'), is constitutively expressed from a Pseudomonas aeruginosa prophage. Tab allows the invading phage replication cycle to proceed, but blocks assembly of the phage tail, thus preventing formation of infectious virions. While the infected cell dies through the activity of the replicating phage lysis proteins, there is no release of infectious phage progeny, and the bacterial community is thereby protected from a phage epidemic. Prophages expressing Tab are not inhibited during their own lytic cycle because they express a counter-defence protein that interferes with Tab function. Thus, our work reveals an anti-phage defence that operates by blocking virion assembly, thereby both preventing formation of phage progeny and allowing destruction of the infected cell due to expression of phage lysis genes.
Topics: Humans; Bacteriophages; Prophages; Pseudomonas Infections; Virion
PubMed: 38388474
DOI: 10.1038/s41467-024-45892-x -
Nature Mar 2022Colibactin is a chemically unstable small-molecule genotoxin that is produced by several different bacteria, including members of the human gut microbiome. Although the...
Colibactin is a chemically unstable small-molecule genotoxin that is produced by several different bacteria, including members of the human gut microbiome. Although the biological activity of colibactin has been extensively investigated in mammalian systems, little is known about its effects on other microorganisms. Here we show that colibactin targets bacteria that contain prophages, and induces lytic development through the bacterial SOS response. DNA, added exogenously, protects bacteria from colibactin, as does expressing a colibactin resistance protein (ClbS) in non-colibactin-producing cells. The prophage-inducing effects that we observe apply broadly across different phage-bacteria systems and in complex communities. Finally, we identify bacteria that have colibactin resistance genes but lack colibactin biosynthetic genes. Many of these bacteria are infected with predicted prophages, and we show that the expression of their ClbS homologues provides immunity from colibactin-triggered induction. Our study reveals a mechanism by which colibactin production could affect microbiomes and highlights a role for microbial natural products in influencing population-level events such as phage outbreaks.
Topics: Bacteria; Bacterial Toxins; Bacteriolysis; Microbial Interactions; Peptides; Polyketides; Prophages; SOS Response, Genetics; Virus Activation
PubMed: 35197633
DOI: 10.1038/s41586-022-04444-3 -
Microbial Genomics Jan 2022The rapid emergence of multidrug-resistant is being driven largely by the spread of specific clonal groups (CGs). Of these, CG147 includes 7-gene multilocus sequence...
The rapid emergence of multidrug-resistant is being driven largely by the spread of specific clonal groups (CGs). Of these, CG147 includes 7-gene multilocus sequence typing (MLST) sequence types (STs) ST147, ST273 and ST392. CG147 has caused nosocomial outbreaks across the world, but its global population dynamics remain unknown. Here, we report a pandrug-resistant ST147 clinical isolate from India (strain DJ) and define the evolution and global emergence of CG147. Antimicrobial-susceptibility testing following European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines and genome sequencing (Illumina and Oxford Nanopore Technologies, Unicycler assembly) were performed on strain DJ. Additionally, we collated 217 publicly available CG147 genomes [National Center for Biotechnology Information (NCBI), May 2019]. CG147 evolution was inferred within a temporal phylogenetic framework (beast) based on a recombination-free sequence alignment (Roary/Gubbins). Comparative genomic analyses focused on resistance and virulence genes and other genetic elements (BIGSdb, Kleborate, PlasmidFinder, phaster, ICEfinder and CRISPRCasFinder). Strain DJ had a pandrug-resistance phenotype. Its genome comprised the chromosome, seven plasmids and one linear phage-plasmid. Four carbapenemase genes were detected: and two copies of in the chromosome, and a second copy of on an 84 kb IncFII plasmid. CG147 genomes carried a mean of 13 acquired resistance genes or mutations; 63 % carried a carbapenemase gene and 83 % harboured . All CG147 genomes presented GyrA and ParC mutations and a common subtype I-E CRISPR-Cas system. ST392 and ST273 emerged in 2005 and 1995, respectively. ST147, the most represented phylogenetic branch, was itself divided into two main clades with distinct capsular loci: KL64 (74 %, DJ included, emerged in 1994 and disseminated worldwide, with carbapenemases varying among world regions) and KL10 (20 %, emerged in 2002, predominantly found in Asian countries, associated with carbapenemases NDM and OXA-48-like). Furthermore, subclades within ST147-KL64 differed at the yersiniabactin locus, OmpK35/K36 mutations, plasmid replicons and prophages. The absence of IncF plasmids in some subclades was associated with a possible activity of a CRISPR-Cas system. CG147 comprises pandrug-resistant or extensively resistant isolates, and carries multiple and diverse resistance genes and mobile genetic elements, including chromosomal . Its emergence is being driven by the spread of several phylogenetic clades marked by their own genomic features and specific temporo-spatial dynamics. These findings highlight the need for precision surveillance strategies to limit the spread of particularly concerning CG147 subsets.
Topics: Drug Resistance, Multiple, Bacterial; Evolution, Molecular; Genome, Bacterial; Genomics; India; Interspersed Repetitive Sequences; Klebsiella pneumoniae; Microbial Sensitivity Tests; Multigene Family; Phylogeny; Plasmids; Prophages; Virulence Factors; Whole Genome Sequencing
PubMed: 35019836
DOI: 10.1099/mgen.0.000737 -
MBio Feb 2024Bacteriophages are large and diverse components of the biosphere, and many phages are temperate. Upon infection, temperate phages can establish lysogeny in which a...
Bacteriophages are large and diverse components of the biosphere, and many phages are temperate. Upon infection, temperate phages can establish lysogeny in which a prophage is typically integrated into the bacterial chromosome. Here, we describe the phenomenon of tRNA-dependent lysogeny, a previously unrecognized behavior of some temperate phages. tRNA-dependent lysogeny is characterized by two unusual features. First, a phage-encoded tyrosine family integrase mediates site-specific recombination between a phage site and a bacterial site overlapping a host tRNA gene. However, and share only a short (~10 bp) common core such that a functional tRNA is not reconstructed upon integration. Second, the phage encodes a tRNA of the same isotype as the disrupted but essential host tRNA, complementing its loss, and consequently is required for the survival of lysogenic progeny. As expected, an integrase-defective phage mutant forms turbid plaques, and bacterial progeny are immune to superinfection, but they lack stability, and the prophage is rapidly lost. In contrast, a tRNA-defective phage mutant forms clear plaques and more closely resembles a repressor mutant, and lysogens are recovered only at very low frequency through the use of secondary attachment sites elsewhere in the host genome. Integration-proficient plasmids derived from these phages must also carry a cognate phage tRNA gene for efficient integration, and these may be useful tools for mycobacterial genetics. We show that tRNA-dependent lysogeny is used by phages within multiple different groups of related viruses and may be prevalent elsewhere in the broader phage community.IMPORTANCEBacteriophages are the most numerous biological entities in the biosphere, and a substantial proportion of phages are temperate, forming stable lysogens in which a prophage copy of the genome integrates into the bacterial chromosome. Many phages encode a variety of tRNA genes whose roles are poorly understood, although it has been proposed that they enhance translational efficiencies in lytic growth or that they counteract host defenses that degrade host tRNAs. Here, we show that phage-encoded tRNAs play key roles in the establishment of lysogeny of some temperate phages. They do so by compensating for the loss of tRNA function when phages integrate at an site overlapping a tRNA gene but fail to reconstruct the tRNA at the attachment junction. In this system of tRNA-dependent lysogeny, the phage-encoded tRNA is required for lysogeny, and deletion of the phage tRNA gives rise to a clear plaque phenotype and obligate lytic growth.
Topics: Lysogeny; Bacteriophages; Prophages; Integrases; Plasmids
PubMed: 38236026
DOI: 10.1128/mbio.03260-23