scholarly journals Introducing a Novel, Broad Host Range Temperate Phage Family Infecting Rhizobium leguminosarum and Beyond

2021 ◽  
Vol 12 ◽  
Author(s):  
Sam Ford ◽  
Sara Moeskjær ◽  
Peter Young ◽  
Rosa I. Santamaría ◽  
Ellie Harrison
Keyword(s):  
Host Range ◽  
Pathogenic Bacteria ◽  
Rhizobium Leguminosarum ◽  
Ecological Impacts ◽  
Lytic Phage ◽  
Broad Host Range ◽  
Host Genus ◽  
History Of ◽  
Active Mobilization ◽  
Genome Comparisons

Temperate phages play important roles in bacterial communities but have been largely overlooked, particularly in non-pathogenic bacteria. In rhizobia the presence of temperate phages has the potential to have significant ecological impacts but few examples have been described. Here we characterize a novel group of 5 Rhizobium leguminosarum prophages, capable of sustaining infections across a broad host range within their host genus. Genome comparisons identified further putative prophages infecting multiple Rhizobium species isolated globally, revealing a wider family of 10 temperate phages including one previously described lytic phage, RHEph01, which appears to have lost the ability to form lysogens. Phylogenetic discordance between prophage and host phylogenies suggests a history of active mobilization between Rhizobium lineages. Genome comparisons revealed conservation of gene content and order, with the notable exception of an approximately 5 kb region of hypervariability, containing almost exclusively hypothetical genes. Additionally, several horizontally acquired genes are present across the group, including a putative antirepressor present only in the RHEph01 genome, which may explain its apparent inability to form lysogens. In summary, both phenotypic and genomic comparisons between members of this group of phages reveals a clade of viruses with a long history of mobilization within and between Rhizobium species.

scholarly journals The Sinorhizobium (Ensifer) fredii HH103 Nodulation Outer Protein NopI Is a Determinant for Efficient Nodulation of Soybean and Cowpea Plants

2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Irene Jiménez-Guerrero ◽  
Francisco Pérez-Montaño ◽  
Carlos Medina ◽  
Francisco Javier Ollero ◽  
Francisco Javier López-Baena
Keyword(s):  
Adenylate Cyclase ◽  
Host Cell ◽  
Host Range ◽  
Pathogenic Bacteria ◽  
Defense Responses ◽  
Host Cells ◽  
Broad Host Range ◽  
Sinorhizobium Fredii ◽  
Symbiotic Efficiency ◽  
Content Type

ABSTRACT The type III secretion system (T3SS) is a specialized secretion apparatus that is commonly used by many plant and animal pathogenic bacteria to deliver proteins, termed effectors, to the interior of the host cells. These effectors suppress host defenses and interfere with signal transduction pathways to promote infection. Some rhizobial strains possess a functional T3SS, which is involved in the suppression of host defense responses, host range determination, and symbiotic efficiency. The analysis of the genome of the broad-host-range rhizobial strain Sinorhizobium fredii HH103 identified eight genes that code for putative T3SS effectors. Three of these effectors, NopL, NopP, and NopI, are Rhizobium specific. In this work, we demonstrate that NopI, whose amino acid sequence shows a certain similarity with NopP, is secreted through the S. fredii HH103 T3SS in response to flavonoids. We also determined that NopL can be considered an effector since it is directly secreted to the interior of the host cell as demonstrated by adenylate cyclase assays. Finally, the symbiotic phenotype of single, double, and triple nopI, nopL, and nopP mutants in soybean and cowpea was assayed, showing that NopI plays an important role in determining the number of nodules formed in both legumes and that the absence of both NopL and NopP is highly detrimental for symbiosis. IMPORTANCE The paper is focused on three Rhizobium-specific T3SS effectors of Sinorhizobium fredii HH103, NopL, NopP, and NopI. We demonstrate that S. fredii HH103 is able to secrete through the T3SS in response to flavonoids the nodulation outer protein NopI. Additionally, we determined that NopL can be considered an effector since it is secreted to the interior of the host cell as demonstrated by adenylate cyclase assays. Finally, nodulation assays of soybean and cowpea indicated that NopI is important for the determination of the number of nodules formed and that the absence of both NopL and NopP negatively affected nodulation.

Disease Resistance Against a Broad-Host-Range Pathogen

2013 ◽  
Vol 14 (1) ◽  
pp. 32
Author(s):  
Jonathan M. Jacobs ◽  
Caitilyn Allen
Keyword(s):  
Disease Resistance ◽  
Host Range ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Pathogenic Bacteria ◽  
Resistance Breeding ◽  
Wilt Disease ◽  
Family Type ◽  
Broad Host Range ◽  
Bacterial Wilt Disease

The bacterial wilt pathogen Ralstonia solanacearum causes major agricultural losses on many crop hosts worldwide. Resistance breeding is the best way to control bacterial wilt disease, but the biological basis for bacterial wilt resistance is unknown. We found that R. solanacearum uses an AvrE-family, Type III-secreted effector called PopS to overcome plant defenses and cause disease on tomato. Orthologs of PopS are widely conserved across distinct classes of plant pathogenic bacteria and could provide novel, durable targets for resistance. Accepted for publication 25 September 2013. Published 25 November 2013.

scholarly journals Broad-Host-Range Shuttle Vectors for Screening of Regulated Promoter Activity in Viridans Group Streptococci: Isolation of a pH-Regulated Promoter

2000 ◽  
Vol 66 (2) ◽  
pp. 535-542 ◽  
Author(s):  
Aldwin J. M. Vriesema ◽  
René Brinkman ◽  
Jan Kok ◽  
Jacob Dankert ◽  
Sebastian A. J. Zaat
Keyword(s):  
Gene Expression ◽  
Host Range ◽  
Pathogenic Bacteria ◽  
Genomic Library ◽  
Regulation Of Gene Expression ◽  
Broad Host Range ◽  
Oral Flora ◽  
Specific Stimulus ◽  
Bacterial Gene ◽  
Viridans Group Streptococci

ABSTRACT Viridans group streptococci are major constituents of the normal human oral flora and are also identified as the predominant pathogenic bacteria in native valve infective endocarditis. Little information is available regarding the regulation of gene expression in viridans group streptococci, either in response to changes in the oral environment or during development of endocarditis. We therefore constructed a set of broad-host-range vectors for the isolation of promoters from viridans group streptococci that are activated by specific environmental stimuli in vitro or in vivo. A genomic library of Streptococcus gordonii strain CH1 was constructed in one of the new vectors, and this library was introduced into a homologous bacterium by using an optimized electroporation protocol for viridans group streptococci. Because viridans group streptococci entering the bloodstream from the oral cavity encounter an increase in pH, we selected promoters upregulated by this specific stimulus. One of the selected promoter sequences showed homology to the promoter region of thehydA gene from Clostridium acetobutylicum, the expression of which is known to be regulated by the environmental pH. The isolation of this pH-regulated promoter shows that S. gordonii can sense an increase in the environmental pH, which serves as a signal for bacterial gene activation. Furthermore, this demonstrates the usefulness of these new selection vectors in research on adaptive gene expression of viridans group streptococci and possibly also of other gram-positive bacteria.

scholarly journals Characterization of novel bacteriophage phiC119 capable of lysing multidrug-resistant Shiga toxin-producingEscherichia coliO157:H7

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2423 ◽  
Author(s):  
Luis Amarillas ◽  
Cristóbal Chaidez ◽  
Arturo González-Robles ◽  
Yadira Lugo-Melchor ◽  
Josefina León-Félix
Keyword(s):  
Host Range ◽  
Shiga Toxin ◽  
Pathogenic Bacteria ◽  
Genetic Material ◽  
Multidrug Resistant ◽  
Broad Host Range ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Tract Infections

BackgroundShiga toxin-producingEscherichia coli(STEC) is one of the most common and widely distributed foodborne pathogens that has been frequently implicated in gastrointestinal and urinary tract infections. Moreover, high rates of multiple antibiotic-resistantE. colistrains have been reported worldwide. Due to the emergence of antibiotic-resistant strains, bacteriophages are considered an attractive alternative to biocontrol pathogenic bacteria. Characterization is a preliminary step towards designing a phage for biocontrol.MethodsIn this study, we describe the characterization of a bacteriophage designated phiC119, which can infect and lyse several multidrug-resistant STEC strains and someSalmonellastrains. The phage genome was screened to detect thestx-genes using PCR, morphological analysis, host range was determined, and genome sequencing were carried out, as well as an analysis of the cohesive ends and identification of the type of genetic material through enzymatic digestion of the genome.ResultsAnalysis of the bacteriophage particles by transmission electron microscopy showed that it had an icosahedral head and a long tail, characteristic of the familySiphoviridae. The phage exhibits broad host range against multidrug-resistant and highly virulentE. coliisolates. One-step growth experiments revealed that the phiC119 phage presented a large burst size (210 PFU/cell) and a latent period of 20 min. Based on genomic analysis, the phage contains a linear double-stranded DNA genome with a size of 47,319 bp. The phage encodes 75 putative proteins, but lysogeny and virulence genes were not found in the phiC119 genome.ConclusionThese results suggest that phage phiC119 may be a good biological control agent. However, further studies are required to ensure its control of STEC and to confirm the safety of phage use.

scholarly journals Phage Therapy for Mycobacterium Abscessus and Strategies to Improve Outcomes

2021 ◽  
Vol 9 (3) ◽  
pp. 596
Author(s):  
Abdolrazagh Hashemi Shahraki ◽  
Mehdi Mirsaeidi
Keyword(s):  
Host Range ◽  
Phage Therapy ◽  
Acquired Resistance ◽  
Severe Case ◽  
Chemotherapeutic Agents ◽  
Mycobacterium Abscessus ◽  
Resistant Bacteria ◽  
Lytic Phage ◽  
Broad Host Range ◽  
Chronic Infections

Members of Mycobacterium abscessus complex are known for causing severe, chronic infections. Members of M. abscessus are a new “antibiotic nightmare” as one of the most resistant organisms to chemotherapeutic agents. Treatment of these infections is challenging due to the either intrinsic or acquired resistance of the M. abscessus complex to the available antibiotics. Recently, successful phage therapy with a cocktail of three phages (one natural lytic phage and two engineered phages) every 12 h for at least 32 weeks has been reported against a severe case of the disseminated M. abscessus subsp. massiliense infection, which underlines the high value of phages against drug-resistant superbugs. This report also highlighted the limitations of phage therapy, such as the absence of lytic phages with a broad host-range against all strains and subspecies of the M. abscessus complex and also the risk of phage resistant bacteria over treatment. Cutting-edge genomic technologies have facilitated the development of engineered phages for therapeutic purposes by introducing new desirable properties, changing host-range and arming the phages with additional killing genes. Here, we review the available literature and suggest new potential solutions based on the progress in phage engineering that can help to overcome the present limitations of M. abscessus treatment.

scholarly journals Characterization of a Broad-Host-Range Lytic Phage SHWT1 Against Multidrug-Resistant Salmonella and Evaluation of Its Therapeutic Efficacy in vitro and in vivo

2021 ◽  
Vol 8 ◽  
Author(s):  
Chenglin Tao ◽  
Zhengfei Yi ◽  
Yaodong Zhang ◽  
Yao Wang ◽  
Hong Zhu ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Host Range ◽  
Therapeutic Efficacy ◽  
Multidrug Resistant ◽  
Lytic Activity ◽  
Resistant Bacteria ◽  
Lytic Phage ◽  
Broad Host Range

Inappropriate use of antibiotics has accelerated to the emergence of multidrug-resistant bacteria, becoming a major health threat. Moreover, bacterial biofilms contribute to antibiotic resistance and prolonged infections. Bacteriophage (phage) therapy may provide an alternative strategy for controlling multidrug-resistant bacterial infections. In this study, a broad-host-range phage, SHWT1, with lytic activity against multidrug-resistant Salmonella was isolated, characterized and evaluated for the therapeutic efficacy in vitro and in vivo. Phage SHWT1 exhibited specific lytic activity against the prevalent Salmonella serovars, such as Salmonella Pullorum, Salmonella Gallinarum, Salmonella Enteritidis, and Salmonella Typhimurium. Morphological analysis showed that phage SHWT1 was a member of the family Siphoviridae and the order Caudovirales. Phage SHWT1 had a latent period of 5 min and burst size of ~150 plaque-forming units (PFUs)/cell. The phage was stable from pH 3-12 and 4–65°C. Phage SHWT1 also showed capacity to lyse Salmonella planktonic cells and inhibit the biofilm formation at optimal multiplicity of infection (MOI) of 0.001, 0.01, 0.1, and 100, respectively. In addition, phage SHWT1 was able to lyse intracellular Salmonella within macrophages. Genome sequencing and phylogenetic analyses revealed that SHWT1 was a lytic phage without toxin genes, virulence genes, antibiotic resistance genes, or significant genomic rearrangements. We found that phage SHWT1 could successfully protect mice against S. enteritidis and S. typhimurium infection. Elucidation of the characteristics and genome sequence of phage SHWT1 demonstrates that this phage is a potential therapeutic agent against the salmonellosis caused by multidrug-resistant Salmonella.

scholarly journals Complete Genome Sequence of the Broad Host Range Single-Stranded RNA Phage PRR1 Places It in the Levivirus Genus with Characteristics Shared with Alloleviviruses

2006 ◽  
Vol 80 (18) ◽  
pp. 9326-9330 ◽  
Author(s):  
Tanja M. Ruokoranta ◽  
A. Marika Grahn ◽  
Janne J. Ravantti ◽  
Minna M. Poranen ◽  
Dennis H. Bamford
Keyword(s):  
Host Range ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Broad Host Range ◽  
Host Genus ◽  
Replicase Proteins ◽  
The Family ◽  
Single Host ◽  
Rna Phage

ABSTRACT Single-stranded RNA (ssRNA) bacteriophages of the family Leviviridae infect gram-negative bacteria. They are restricted to a single host genus. Phage PRR1 is an exception, having a broad host range due to the promiscuity of the receptor encoded by the IncP plasmid. Here we report the complete genome sequence of PRR1. Three proteins homologous with those of other ssRNA phages, i.e., maturation, coat, and replicase proteins, were identified. A fourth protein has a lysis function. Comparison of PRR1 with other members of the Leviviridae family places PRR1 in the genus Levivirus with some characteristics more similar to those of members of the genus Allolevivirus.

scholarly journals Characterisation of Bacteriophage-Encoded Depolymerases Selective for Key Klebsiella pneumoniae Capsular Exopolysaccharides

2021 ◽  
Vol 11 ◽  
Author(s):  
George Blundell-Hunter ◽  
Mark C. Enright ◽  
David Negus ◽  
Matthew J. Dorman ◽  
Gemma E. Beecham ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Host Range ◽  
Multiple Drug Resistance ◽  
Sewage Water ◽  
Multiple Drug ◽  
Lytic Phage ◽  
Broad Host Range ◽  
Capsular Polysaccharides ◽  
Protein Database ◽  
Rolling Ball

Capsular polysaccharides enable clinically important clones of Klebsiella pneumoniae to cause severe systemic infections in susceptible hosts. Phage-encoded capsule depolymerases have the potential to provide an alternative treatment paradigm in patients when multiple drug resistance has eroded the efficacy of conventional antibiotic chemotherapy. An investigation of 164 K. pneumoniae from intensive care patients in Thailand revealed a large number of distinct K types in low abundance but four (K2, K51, K1, K10) with a frequency of at least 5%. To identify depolymerases with the capacity to degrade capsules associated with these common K-types, 62 lytic phage were isolated from Thai hospital sewage water using K1, K2 and K51 isolates as hosts; phage plaques, without exception, displayed halos indicative of the presence of capsule-degrading enzymes. Phage genomes ranged in size from 41–348 kb with between 50 and 535 predicted coding sequences (CDSs). Using a custom phage protein database we were successful in applying annotation to 30 - 70% (mean = 58%) of these CDSs. The largest genomes, of so-called jumbo phage, carried multiple tRNAs as well as CRISPR repeat and spacer sequences. One of the smaller phage genomes was found to contain a putative Cas type 1E gene, indicating a history of host DNA acquisition in these obligate lytic phage. Whole-genome sequencing (WGS) indicated that some phage displayed an extended host range due to the presence of multiple depolymerase genes; in total, 42 candidate depolymerase genes were identified with up to eight in a single genome. Seven distinct virions were selected for further investigation on the basis of host range, phage morphology and WGS. Candidate genes for K1, K2 and K51 depolymerases were expressed and purified as his6-tagged soluble protein and enzymatic activity demonstrated against K. pneumoniae capsular polysaccharides by gel electrophoresis and Anton-Paar rolling ball viscometry. Depolymerases completely removed the capsule in K-type-specific fashion from K. pneumoniae cells. We conclude that broad-host range phage carry multiple enzymes, each with the capacity to degrade a single K-type, and any future use of these enzymes as therapeutic agents will require enzyme cocktails for utility against a range of K. pneumoniae infections.

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