9 results on '"Langford, Paul R."'
Search Results
2. Evidence of illegitimate recombination between two Pasteurellaceae plasmids resulting in a novel multi-resistance replicon, pM3362MDR, in Actinobacillus pleuropneumoniae
- Author
-
Silva, Giarlã Cunha da, Li, Yinghui, Li, Yanwen, Rossi, Ciro C., Crespo, Roberto Fernandez, Williamson, Susanna M., Langford, Paul R., Bazzolli, Denise Mara Soares, Bossé, Janine T., Biotechnology and Biological Sciences Research Council (BBSRC), BBSRC, and NC3Rs (National Centre for the Replacement, Refinement and Reduction of Animals in Research)
- Subjects
plasmids ,Science & Technology ,GENES ,IDENTIFICATION ,SEQUENCES ,HAEMOPHILUS-PARASUIS ,Respiratory tract ,Tetracycline ,Antimicrobial resistance ,respiratory tract ,RELAXASES ,Microbiology ,MULTOCIDA ,ANTIMICROBIAL-RESISTANCE ,CONJUGATIVE ELEMENT ICE ,TRANSFER ORIGIN ,PIGS ,antimicrobial resistance ,Pasteurellaceae ,Life Sciences & Biomedicine ,Plasmids ,tetracycline - Abstract
Evidence of plasmids carrying the tetracycline resistance gene, tet(B), was found in the previously reported whole genome sequences of 14 United Kingdom, and 4 Brazilian, isolates of Actinobacillus pleuropneumoniae. Isolation and sequencing of selected plasmids, combined with comparative sequence analysis, indicated that the four Brazilian isolates all harbor plasmids that are nearly identical to pB1001, a plasmid previously found in Pasteurella multocida isolates from Spain. Of the United Kingdom isolates, 13/14 harbor plasmids that are (almost) identical to pTetHS016 from Haemophilus parasuis. The remaining United Kingdom isolate, MIDG3362, harbors a 12666 bp plasmid that shares extensive regions of similarity with pOV from P. multocida (which carries bla ROB−1 , sul2, and strAB genes), as well as with pTetHS016. The newly identified multi-resistance plasmid, pM3362MDR, appears to have arisen through illegitimate recombination of pTetHS016 into the stop codon of the truncated strB gene in a pOV-like plasmid. All of the tet(B)-carrying plasmids studied were capable of replicating in Escherichia coli, and predicted origins of replication were identified. A putative origin of transfer (oriT) sequence with similar secondary structure and a nic-site almost identical to that of RP4 was also identified in these plasmids, however, attempts to mobilize them from an RP4-encoding E. coli donor strain were not successful, indicating that specific conjugation machinery may be required.
- Published
- 2018
3. Proposal of serovars 17 and 18 of Actinobacillus pleuropneumoniae based on serological and genotypic analysis
- Author
-
Bossé, Janine T, Li, Yanwen, Sárközi, Rita, Fodor, László, Lacouture, Sonia, Gottschalk, Marcelo, Casas Amoribieta, Maria, Angen, Øystein, Nedbalcova, Katerina, Holden, Matthew TG, Maskell, Duncan J, Tucker, Alexander W, Wren, Brendan W, Rycroft, Andrew N, Langford, Paul R, BRaDP1T consortium, Biotechnology and Biological Sciences Research Council (BBSRC), Pfizer Limited (UK), Biotechnology and Biological Sciences Research Council, University of St Andrews. School of Medicine, University of St Andrews. Infection and Global Health Division, University of St Andrews. Infection Group, and University of St Andrews. Biomedical Sciences Research Complex
- Subjects
0301 basic medicine ,Serotype ,Swine ,Biovar ,animal diseases ,Denmark ,DIVERSITY ,Polymerase Chain Reaction ,Actinobacillus Infections ,Genotype ,ASSAY ,Diagnostics ,Genetics ,Swine Diseases ,biology ,Structural gene ,Actinobacillus pleuropneumoniae ,General Medicine ,3. Good health ,PCR ,Serovar 18 ,SEROTYPE-2 ,Serovar 17 ,QR355 Virology ,Life Sciences & Biomedicine ,MULTIPLEX PCR ,0605 Microbiology ,DNA, Bacterial ,Canada ,GENES ,030106 microbiology ,Locus (genetics) ,QH426 Genetics ,Serogroup ,Microbiology ,Article ,03 medical and health sciences ,BRaDP1T consortium ,Animals ,BIOSYNTHESIS ,Veterinary Sciences ,Serotyping ,CAPSULAR POLYSACCHARIDES ,Gene ,QH426 ,Bacterial Capsules ,DNA Primers ,Whole genome sequencing ,QR355 ,Science & Technology ,General Veterinary ,IDENTIFICATION ,Whole Genome Sequencing ,0707 Veterinary Sciences ,STRAINS ,DAS ,biology.organism_classification ,bacterial infections and mycoses ,Capsule genes - Abstract
Highlights • Identification of two new serovars of Actinobacillus pleuropneumoniae. • Serological confirmation of specific reactivity with homologous antisera. • Characterization of the capsule loci of serovars 17 and 18. • Development of PCRs for molecular diagnostics., The aim of this study was to investigate isolates of Actinobacillus pleuropneumoniae previously designated serologically either as non-typable (NT) or as ‘K2:07’, which did not produce serovar-specific amplicons in PCR assays. We used whole genome sequencing to identify the capsule (CPS) loci of six previously designated biovar 1 NT and two biovar 1 ‘K2:O7’ isolates of A. pleuropneumoniae from Denmark, as well as a recent biovar 2 NT isolate from Canada. All of the NT isolates have the same six-gene type I CPS locus, sharing common cpsABC genes with serovars 2, 3, 6, 7, 8, 9, 11 and 13. The two ‘K2:O7’ isolates contain a unique three-gene type II CPS locus, having a cpsA gene similar to that of serovars 1, 4, 12, 14 and 15. The previously NT isolates share the same O-antigen genes, found between erpA and rpsU, as serovars 3, 6, 8, and 15. Whereas the ‘K2:O7’ isolates, have the same O-antigen genes as serovar 7, which likely contributed to their previous mis-identification. All of the NT and ‘K2:O7’ isolates have only the genes required for production of ApxII (apxIICA structural genes, and apxIBD export genes). Rabbit polyclonal antisera raised against representative isolates with these new CPS loci demonstrated distinct reactivity compared to the 16 known serovars. The serological and genomic results indicate that the isolates constitute new serovars 17 (previously NT) and 18 (previously ‘K2:O7’). Primers designed for amplification of specific serovar 17 and 18 sequences for molecular diagnostics will facilitate epidemiological tracking of these two new serovars of A. pleuropneumoniae.
- Published
- 2018
4. A Rare Mutation in SPLUNC1 Affects Bacterial Adherence and Invasion in Meningococcal Disease.
- Author
-
Mashbat, Bayarchimeg, Bellos, Evangelos, Hodeib, Stephanie, Bidmos, Fadil, Thwaites, Ryan S, Lu, Yaxuan, Wright, Victoria J, Herberg, Jethro A, Klobassa, Daniela S, Zenz, Werner, Hansel, Trevor T, Nadel, Simon, Langford, Paul R, Schlapbach, Luregn J, Li, Ming-Shi, Redinbo, Matthew R, Di, Y Peter, Levin, Michael, and Sancho-Shimizu, Vanessa
- Subjects
BACTERIAL physiology ,BIOFILMS ,COMPARATIVE studies ,GENE expression ,GENES ,GENETIC polymorphisms ,GENOMES ,GENETIC mutation ,NEISSERIA meningitidis ,SEPSIS ,DESCRIPTIVE statistics ,SEQUENCE analysis ,IN vitro studies - Abstract
Background Neisseria meningitidis (Nm) is a nasopharyngeal commensal carried by healthy individuals. However, invasive infections occurs in a minority of individuals, with devastating consequences. There is evidence that common polymorphisms are associated with invasive meningococcal disease (IMD), but the contributions of rare variants other than those in the complement system have not been determined. Methods We identified familial cases of IMD in the UK meningococcal disease study and the European Union Life-Threatening Infectious Disease Study. Candidate genetic variants were identified by whole-exome sequencing of 2 patients with familial IMD. Candidate variants were further validated by in vitro assays. Results Exomes of 2 siblings with IMD identified a novel heterozygous missense mutation in BPIFA1 / SPLUNC1. Sequencing of 186 other nonfamilial cases identified another unrelated IMD patient with the same mutation. SPLUNC1 is an innate immune defense protein expressed in the nasopharyngeal epithelia; however, its role in invasive infections is unknown. In vitro assays demonstrated that recombinant SPLUNC1 protein inhibits biofilm formation by Nm, and impedes Nm adhesion and invasion of human airway cells. The dominant negative mutant recombinant SPLUNC1 (p.G22E) showed reduced antibiofilm activity, increased meningococcal adhesion, and increased invasion of cells, compared with wild-type SPLUNC1. Conclusions A mutation in SPLUNC1 affecting mucosal attachment, biofilm formation, and invasion of mucosal epithelial cells is a new genetic cause of meningococcal disease. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
5. Characterization of the Actinobacillus pleuropneumoniae SXT-related integrative and conjugative element ICEApl2 and analysis of the encoded FloR protein: hydrophobic residues in transmembrane domains contribute dynamically to florfenicol and chloramphenicol efflux.
- Author
-
Yinghui Li, Yanwen Li, Fernandez Crespo, Roberto, Leanse, Leon G., Langford, Paul R., Bossé, Janine T., Li, Yinghui, and Li, Yanwen
- Subjects
ACTINOBACILLUS pleuropneumoniae ,MEMBRANE proteins ,HYDROPHOBIC interactions ,CHLORAMPHENICOL ,SITE-specific mutagenesis ,DRUG resistance in bacteria ,TRIMETHOPRIM ,THERAPEUTICS - Abstract
Objectives: To characterize ICEApl2, an SXT-related integrative and conjugative element (ICE) found in a clinical isolate of the porcine pathogen Actinobacillus pleuropneumoniae, and analyse the functional nature of the encoded FloR.Methods: ICEApl2 was identified in the genome of A. pleuropneumoniae MIDG3553. Functional analysis was done using conjugal transfer experiments. MIDG3553 was tested for susceptibility to the antimicrobials for which resistance genes are present in ICEApl2. Lack of florfenicol/chloramphenicol resistance conferred by the encoded FloR protein was investigated by cloning and site-directed mutagenesis experiments in Escherichia coli.Results: ICEApl2 is 92660 bp and contains 89 genes. Comparative sequence analysis indicated that ICEApl2 is a member of the SXT/R391 ICE family. Conjugation experiments showed that, although ICEApl2 is capable of excision from the chromosome, it is not self-transmissible. ICEApl2 encodes the antimicrobial resistance genes floR, strAB, sul2 and dfrA1, and MIDG3553 is resistant to streptomycin, sulfisoxazole and trimethoprim, but not florfenicol or chloramphenicol. Cloning and site-directed mutagenesis of the floR gene revealed the importance of the nature of the hydrophobic amino acid residues at positions 160 and 228 in FloR for determining resistance to florfenicol and chloramphenicol.Conclusions: Our results indicate that the nature of hydrophobic residues at positions 160 and 228 of FloR contribute dynamically to specific efflux of florfenicol and chloramphenicol, although some differences in resistance levels may depend on the bacterial host species. This is also, to our knowledge, the first description of an SXT/R391 ICE in A. pleuropneumoniae or any member of the Pasteurellaceae. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
6. Transcriptional Profiling of Serogroup B Neisseria meningitidis Growing in Human Blood: An Approach to Vaccine Antigen Discovery.
- Author
-
Hedman, Asa K., Ming-Shi Li, Langford, Paul R., and Kroll, J. Simon
- Subjects
NEISSERIA meningitidis ,SEPSIS ,BLOOD ,GENES ,ENERGY metabolism ,MOLECULAR chaperones - Abstract
Neisseria meningitidis is a nasopharyngeal commensal of humans which occasionally invades the blood to cause septicaemia. The transcriptome of N. meningitidis strain MC58 grown in human blood for up to 4 hours was determined and around 10% of the genome was found to be differentially regulated. The nuo, pet and atp operons, involved in energy metabolism, were up-regulated, while many house-keeping genes were down-regulated. Genes encoding protein chaperones and proteases, involved in the stress response; complement resistant genes encoding enzymes for LOS sialylation and biosynthesis; and fHbp (NMB1870) and nspA (NMB0663), encoding vaccine candidates, were all up-regulated. Genes for glutamate uptake and metabolism, and biosynthesis of purine and pyrimidine were also up-regulated. Blood grown meningococci are under stress and undergo a metabolic adaptation and energy conservation strategy. The localisation of four putative outer membrane proteins encoded by genes found to be up-regulated in blood was assessed by FACS using polyclonal mouse antisera, and one (NMB0390) showed evidence of surface expression, supporting its vaccine candidacy. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
7. The role of the Shigella flexneri yihE gene in LPS synthesis and virulence.
- Author
-
Edwards-Jones, Bryn, Langford, Paul R., Kroll, J. Simon, and Jun Yu
- Subjects
- *
SHIGELLA flexneri , *GENES , *MICROBIAL virulence , *GENE expression , *ACTIN , *GLUCOSE - Abstract
Previously, the authors have shown that inactivation of Shigella flexneri yihE, a gene of unknown function upstream of dsbA, which encodes a periplasmic disulphide catalyst, results in a global change of gene expression. Among the severely down-regulated genes are galETKM, suggesting that the yihE mutant, Sh54, may inefficiently produce the UDP-glucose and UDP-galactose required for LPS synthesis. This paper demonstrates that LPS synthesis in Sh54 is impaired. As a result, Sh54 is unable to polymerize host cell actin, due to aberrant localization of IcsA, or to cause keratoconjunctivitis in guinea pigs. Furthermore, Sh54 is more sensitive to some antimicrobial agents, and exhibits epithelial cytotoxicity characteristic of neither wild-type nor dsbA mutants. Supplying galETK in trans restores LPS synthesis and corrects all the defects. Hence, it is clear that the Shigella yihE gene is important not only in regulating global gene expression, as shown previously, but also in virulence through LPS synthesis via regulating the expression of the galETK operon. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
8. Differential contribution of sodC1 and sodC2 to intracellular survival and pathogenicity of Salmonella enterica serovar Choleraesuis
- Author
-
Ammendola, Serena, Ajello, Maria, Pasquali, Paolo, Kroll, J. Simon, Langford, Paul R., Rotilio, Giuseppe, Valenti, Piera, and Battistoni, Andrea
- Subjects
- *
GENES , *ENTEROBACTERIACEAE , *SALMONELLA , *SUPEROXIDES - Abstract
Abstract: Several of the most virulent Salmonella enterica strains possess two genes encoding periplasmic Cu,Zn superoxide dismutase, sodC1 and sodC2, located on a lambdoid prophage and on the chromosome, respectively. These genes contribute to Salmonella virulence by protecting bacteria from superoxide generated by the host''s phagocytes. To investigate the respective contributions of sodC1 and sodC2 to the virulence of a clinical isolate of Salmonella enterica serovar Choleraesuis (S. choleraesuis), we have analyzed both the intracellular survival of wild type and sodC mutant strains within J774 macrophages and Caco-2 cells, and their ability to proliferate in intraperitoneally-infected mice in competition assays. In agreement with previous studies, mutant strains lacking one or both sodC genes were equally impaired in their ability to survive within activated macrophages. However, when macrophage killing experiments were carried out with non-opsonized bacteria, sodC2 contributed to intracellular survival more than sodC1, indicating that changes in the pathways of bacterial uptake can modify the relative role of the two sodC genes. More unexpectedly, we have found that the ability of S. choleraesuis to survive within Caco-2 cells was severely affected by inactivation of sodC genes, sodC2 being more important than sodC1. As Caco-2 cells actively produce superoxide, this suggests that oxygen radical production by colonic cells has a role in controlling proliferation of facultative intracellular bacteria. Mouse infection studies confirmed that, in the S. choleraesuis strain under investigation, both sodC genes are required to confer full virulence, sodC2 contributing slightly more than sodC1 to Salmonella pathogenesis. Our findings contrast with the results of other studies carried out in S. enterica serovar Typhimurium and suggest that the relative contributions of sodC1 and sodC2 to host-pathogen interactive biology may vary depending on the Salmonella serovar or strain. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
9. Proposal of Actinobacillus pleuropneumoniae serovar 19, and reformulation of previous multiplex PCRs for capsule-specific typing of all known serovars.
- Author
-
Stringer, Oliver W., Bossé, Janine T., Lacouture, Sonia, Gottschalk, Marcelo, Fodor, László, Angen, Øystein, Velazquez, Eduardo, Penny, Paul, Lei, Liancheng, Langford, Paul R., and Li, Yanwen
- Subjects
- *
ACTINOBACILLUS pleuropneumoniae , *GENES , *POLYMERASE chain reaction , *GENOTYPES - Abstract
[Display omitted] • Identification of A. pleuropneumoniae serovar 19 type II capsule locus. • Serovar 19 isolates are biovar 1, encode ApxII and ApxIV toxins, and have either a serogroup 3/6/8/15 or 4/7 O-Ag locus. • Reformulation of two mPCRs for unequivocal capsule typing of all known A. pleuropneumoniae serovars. Two serologically and molecularly non-typeable isolates of the porcine lung pathogen Actinobacillus pleuropneumoniae have been identified from diseased swine in two different continents. Genome sequencing was carried out to identify their diagnostically relevant genotypes. Both isolates are biovar 1 and encode genes for production of ApxIV and ApxII (apxIICA structural genes, and apxIBD export genes). They both possess the same novel type II capsule locus (most similar to serovar 1, but with two capsule genes not previously found in A. pleuropneumoniae) but differ in their O-Ag loci. Strain 7213384-1 from Denmark, which we propose as the reference strain for serovar 19, has a serogroup 3/6/8/15 O-Ag locus; the Canadian isolate A08-013 has a serogroup 4/7 O-Ag locus. We have expanded the second of our two previously described A. pleuropneumoniae mPCRs to include capsule gene-specific primers for definitive detection of serovars 13–14 and 16–19. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.