Andrew Rycroft
Royal Veterinary College, Pathology and Infectious Diseases, Faculty Member
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Research Interests: Genetics, Molecular Biology, Biology, Medicine, Multidisciplinary, and 12 moreMethods, Applied, Applied Environmental Microbiology, Bacteria, Plasmids, Molecular cloning, Pasteurella Multocida, Base Sequence, Actinobacillus pleuropneumoniae, Plasmid, Haemophilus influenzae, and Molecular Sequence Data
Research Interests: Immune response, Biology, Helicobacter pylori, Biological Sciences, Histidine kinase, and 15 moreEscherichia coli, Female, Animals, Blood, Infection, Flagella, Chemotaxis, Genome sequence, Gastric Ulcer, Enzyme Linked Immunosorbent Assay, H Pylori, Gastric mucosa, Antibody Response, Gastric Adenocarcinoma, and flagellum
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Actinobacillus pleuropneumoniae causes porcine pleuropneumonia, a highly infectious and commonly lethal disease in pigs.1 It is present in porcine respiratory tract wherever pig production is industrialised, but it is not considered to be... more
Actinobacillus pleuropneumoniae causes porcine pleuropneumonia, a highly infectious and commonly lethal disease in pigs.1 It is present in porcine respiratory tract wherever pig production is industrialised, but it is not considered to be zoonotic.2 To our knowledge, no cases of infection have been reported in animals other than pigs or in humans, including abattoir and farm workers. Vaccinating pigs against pleuropneumonia is an important …
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Research Interests: Pharmacology, Microbiology, Veterinary Medicine, Biology, Pharmacokinetics, and 15 moreMedicine, Veterinary, Veterinary Science, Biological Sciences, Salmonella enteritidis, Bioavailability, Pharmacodynamics, Veterinary Sciences, Pasteurella Multocida, Broiler, Enrofloxacin, Mycoplasma gallisepticum, Pharmacology and pharmaceutical sciences, Minimum Inhibitory Concentration, and Cmax
Research Interests: Clinical Trial, Biology, Drug Discovery, Biological Sciences, Escherichia coli, and 15 moreFemale, Animals, Clinical, Integration, High Performance Liquid Chromatography, High Pressure Liquid Chromatography, Amoxicillin, Antimicrobial agents, Body Weight, Bacterial Infection, Area Under Curve, Fluoroquinolones, Escherichia Coli Infections, Enrofloxacin, and Florfenicol
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Research Interests: Microbiology, Immunology, Medical Microbiology, Biology, Aquaculture, and 15 moreMedicine, Female, Animals, Male, Microbial Pathogenesis, Cattle, Microbial Sensitivity Tests, Pasteurella Multocida, Actinobacillus pleuropneumoniae, Oxytetracycline, Mannheimia Haemolytica, Area Under Curve, Exudates and Transudates, Fluoroquinolones, and beagle
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The genetic determinants of the 120-kDa cytotoxin of Actinobacillus pleuropneumoniae serotype 2 were isolated from a lambda DNA library by a plaque immunoblot technique. Expression of the 120-kDa polypeptide was confirmed by Western... more
The genetic determinants of the 120-kDa cytotoxin of Actinobacillus pleuropneumoniae serotype 2 were isolated from a lambda DNA library by a plaque immunoblot technique. Expression of the 120-kDa polypeptide was confirmed by Western immunoblot analysis of infected Escherichia coli cell lysates, which were shown to be toxic for porcine alveolar macrophages in vitro. The genetic determinants of the toxin were subcloned into the plasmid vector pUC18. This plasmid (pPTX1) directed the synthesis and secretion of the active 120-kDa cytotoxin in E. coli. The recombinant toxin was indistinguishable from native cytotoxin from A. pleuropneumoniae serotype 2 with respect to molecular size, reaction in Western blot analysis, heat lability, cytotoxic activity, and neutralization by serum antibody. A restriction endonuclease cleavage map of pPTX1 was prepared, and deletion mutants were used to locate the minimal region of DNA required for production of intracellular toxin; this gene was termed pt...
Research Interests: Microbiology, Molecular Biology, Biology, Medicine, Gene expression, and 11 moreBiological Sciences, Infection and immunity, Escherichia coli, Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis, Molecular cloning, Time Factors, Actinobacillus pleuropneumoniae, Recombinant Proteins, Cytotoxins, Restriction Mapping, and Medical and Health Sciences
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Actinobacillus pleuropneumoniae causes porcine pleuropneumonia, a highly infectious and commonly lethal disease in pigs.1 It is present in porcine respiratory tract wherever pig production is industrialised, but it is not considered to be... more
Actinobacillus pleuropneumoniae causes porcine pleuropneumonia, a highly infectious and commonly lethal disease in pigs.1 It is present in porcine respiratory tract wherever pig production is industrialised, but it is not considered to be zoonotic.2 To our knowledge, no cases of infection have been reported in animals other than pigs or in humans, including abattoir and farm workers. Vaccinating pigs against pleuropneumonia is an important …
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Research Interests: Microbiology, Immune response, Biology, Medicine, Gene expression, and 15 moreAnimal Production, Veterinary, Veterinary Science, Respiratory Disease, Mutation, Animals, Gene transfer techniques, Polymerase Chain Reaction, Swine, Respiratory Tract Infections, Veterinary Sciences, Actinobacillus pleuropneumoniae, Residence Time, Serotype, and alleles
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Research Interests: Genetics, Gene regulation, Biology, Medicine, Antibiotic Resistance, and 15 moreEnergy Metabolism, Biological Sciences, Lipopolysaccharide, Stress response, Nutrient Uptake, Gene, Hot Spot, Indexation, Actinobacillus pleuropneumoniae, Bacterial Infection, DNA sequence, Chronic Infection, Antibiotic treatment, Medical and Health Sciences, and Failure to Thrive
Comprehensive identification of conditionally essential genes requires efficient tools for generating high-density transposon libraries that, ideally, can be analysed using next-generation sequencing methods such as Transposon Directed... more
Comprehensive identification of conditionally essential genes requires efficient tools for generating high-density transposon libraries that, ideally, can be analysed using next-generation sequencing methods such as Transposon Directed Insertion-site Sequencing (TraDIS). The Himar1 (mariner) transposon is ideal for generating near-saturating mutant libraries, especially in AT-rich chromosomes, as the requirement for integration is a TA dinucleotide, and this transposon has been used for mutagenesis of a wide variety of bacteria. However, plasmids for mariner delivery do not necessarily work well in all bacteria. In particular, there are limited tools for functional genomic analysis of Pasteurellaceae species of major veterinary importance, such as swine and cattle pathogens, Actinobacillus pleuropneumoniae and Pasteurella multocida, respectively. Here, we developed plasmids, pTsodCPC9 and pTlacPC9 (differing only in the promoter driving expression of the transposase gene), that allo...
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We report here the complete genome sequence of the widely studied Actinobacillus pleuropneumoniae serovar 8 reference strain 405, generated using the Pacific Biosciences (PacBio) RS II platform. Furthermore, we compared draft sequences... more
We report here the complete genome sequence of the widely studied Actinobacillus pleuropneumoniae serovar 8 reference strain 405, generated using the Pacific Biosciences (PacBio) RS II platform. Furthermore, we compared draft sequences generated by Illumina sequencing of six stocks of this strain, including the same original stock used to generate the PacBio sequence, held in different countries and found little genetic variation, with only three SNPs identified, all within the degS gene. However, sequences of two small plasmids, pARD3079 and p405tetH, detected by Illumina sequencing of the draft genomes were not identified in the PacBio sequence of the reference strain.
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Glaesserella ( Haemophilus ) parasuis is a commensal bacterium of the upper respiratory tract in pigs and also the causative agent of Glässer’s disease, which causes significant morbidity and mortality in pigs worldwide. Isolates are... more
Glaesserella ( Haemophilus ) parasuis is a commensal bacterium of the upper respiratory tract in pigs and also the causative agent of Glässer’s disease, which causes significant morbidity and mortality in pigs worldwide. Isolates are characterized into 15 serovars by their capsular polysaccharide, which has shown a correlation with isolate pathogenicity. To investigate the role the capsule plays in G. parasuis virulence and host interaction, a capsule mutant of the serovar 5 strain HS069 was generated (HS069Δcap) through allelic exchange following natural transformation.
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Streptococcus suis is one of the most important zoonotic bacterial pathogens of pigs, causing significant economic losses to the global swine industry. S. suis is also a very successful colonizer of mucosal surfaces, and commensal strains... more
Streptococcus suis is one of the most important zoonotic bacterial pathogens of pigs, causing significant economic losses to the global swine industry. S. suis is also a very successful colonizer of mucosal surfaces, and commensal strains can be found in almost all pig populations worldwide, making detection of the S. suis species in asymptomatic carrier herds of little practical value in predicting the likelihood of future clinical relevance.
Research Interests: Microbiology, Biology, Medicine, Molecular Diagnostics, England, and 15 moreClinical Microbiology, Biological Sciences, Identification, Animals, Disease, Pathogen, Molecular Diagnostic Techniques, Asymptomatic, Bacterial Pathogens, Genetic Markers, Pathotyping, Capsular types, Carrier state, Medical and Health Sciences, and multiplex polymerase chain reaction
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Transmission of Actinobacillus pleuropneumoniae is primarily thought to be via direct transfer of mucus from pig to pig. For transfer between farms, the organism may need to persist in the wet or dried state to be carried on an inanimate... more
Transmission of Actinobacillus pleuropneumoniae is primarily thought to be via direct transfer of mucus from pig to pig. For transfer between farms, the organism may need to persist in the wet or dried state to be carried on an inanimate surface. The survival of A. pleuropneumoniae was investigated under controlled laboratory conditions. In aqueous suspension, survival was improved by the presence of NaCl and mucin; it was prolonged at lower temperature. In dry state, it survived best on a hydrophobic surface either under desiccated conditions or saturated humidity. Detectable viability was maintained for 3-4 days. When frozen, A. pleuropneumoniae survived for more than 17 weeks at -20 °C, but the viability declined to 0.01% during that time. Survival at -70 °C was effective for long term storage. Results obtained from this investigation would be applicable for sampling method, transport techniques, epidemiological study, and biosecurity implementation.
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BackgroundGlaesserella parasuis, the causative agent of Glӓsser’s disease, is widespread in swine globally resulting in significant economic losses to the swine industry. Prevention of Glӓsser’s disease in pigs has been plagued with an... more
BackgroundGlaesserella parasuis, the causative agent of Glӓsser’s disease, is widespread in swine globally resulting in significant economic losses to the swine industry. Prevention of Glӓsser’s disease in pigs has been plagued with an inability to design broadly protective vaccines, as many bacterin based platforms generate serovar or strain specific immunity. Subunit vaccines are of interest to provide protective immunity to multiple strains ofG. parasuis. Selected proteins for subunit vaccination should be widespread, highly conserved, and surface exposed.ResultsTwo candidate proteins for subunit vaccination (RlpB and VacJ) againstG. parasuiswere identified using random mutagenesis and an in vitro organ culture system. Pigs were vaccinated with recombinant RlpB and VacJ, outer membrane proteins with important contributions to cellular function and viability. Though high antibody titers to the recombinant proteins and increased interferon-γ producing cells were found in subunit va...
Research Interests: Microbiology, Biology, Virology, Medicine, Immunity, and 14 moreAnimals, Vaccination, Recombinant DNA, Antibody, Swine, Haemophilus parasuis, Veterinary Sciences, Swine Diseases, Recombinant Proteins, Sus Scrofa, Haemophilus Infections Market, Biochemistry and cell biology, Tissue culture techniques, and Serogroup
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This chapter discusses the chemical structure, biological function, biosynthesis and genetics of the surface polysaccharides found on the surface of Salmonella spp.
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This chapter describes the phylogenetics, culture and pathogenicity of Mycoplasma species in pigs.
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word count 225 (Max 250) 34 Haemophilus parasuis is a diverse bacterial species found in the upper respiratory 35 tract of pigs that can also cause Glässer’s disease and pneumonia. A previous pan36 genome study of H. parasuis identified... more
word count 225 (Max 250) 34 Haemophilus parasuis is a diverse bacterial species found in the upper respiratory 35 tract of pigs that can also cause Glässer’s disease and pneumonia. A previous pan36 genome study of H. parasuis identified 48 genes that were associated with clinical 37 disease. Here we describe the development of a generalised linear model (termed a 38 pathotyping model) to predict the potential virulence of isolates of H. parasuis, based 39 on a subset of 10 genes from the pan-genome. A multiplex PCR (mPCR) was 40 constructed based on these genes, the results of which were entered into the 41 pathotyping model to yield a prediction of virulence. This new diagnostic mPCR was 42 tested on 143 field isolates of H. parasuis that had previously been whole-genome 43 sequenced and a further 84 isolates from the UK from cases of H. parasuis-related 44 disease in pigs collected between 2013 and 2014. The combination of the mPCR and 45 on A uust 2, 2017 by gest ht://jcm .sm .rg...
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30 Haemophilus parasuis causes Glässer’s disease and pneumonia in pigs. Indirect haemagglutination (IHA) is 31 used to serotype this bacterium, distinguishing fifteen serovars with some non-typeable isolates. The capsule 32 loci of the... more
30 Haemophilus parasuis causes Glässer’s disease and pneumonia in pigs. Indirect haemagglutination (IHA) is 31 used to serotype this bacterium, distinguishing fifteen serovars with some non-typeable isolates. The capsule 32 loci of the fifteen reference strains were annotated and significant genetic variation was identified between 33 serovars, with the exception of serovars 5 and 12. A capsule locus and in silico serovar was identified for all 34 but two non-typeable isolates in our collection of over 200 isolates. Here we describe the development of a 35 multiplex PCR, based on variation within the capsule loci of the fifteen serovars of H. parasuis, for rapid 36 molecular serotyping. The mPCR distinguished between all previously described serovars except 5 and 12, 37 which were detected by the same pair of primers. The detection limit of the mPCR was 4.29x10 ng/μl 38 bacterial genomic DNA and high specificity was indicated by the absence of reactivity against closely 39 related c...
Mycoplasma hyopneumoniae is the etiologic agent of porcine enzootic pneumonia, responsible for major production losses worldwide. The bacteria have a limited metabolism and need to obtain molecules from the growth environment, which... more
Mycoplasma hyopneumoniae is the etiologic agent of porcine enzootic pneumonia, responsible for major production losses worldwide. The bacteria have a limited metabolism and need to obtain molecules from the growth environment, which causes multiple difficulties for in vitro culture. These limitations have a negative influence on the ability to carry out research for the development of the rational use of antimicrobials and vaccines. The objective of this investigation was to evaluate the genetic profile and in vitro susceptibility of field isolates of M. hyopneumoniae to different antimicrobials. All 16 isolates obtained from the samples presented 100% of identity in the partial sequence of 16S rRNA gene when compared to M. hyopneumoniae. A dendrogram was created using the PCR results of the genes related to pathogenicity, and the isolates were distributed into four clusters, suggesting genetic variability among four different isolates circulating on the same farm. The minimum inhibitory concentration of the isolates was higher for the antimicrobials tylosin (< 0.001-16 mg/L) and spiramycin (< 0.001-16 mg/L) than for enrofloxacin (< 0.001-0.125 mg/L) and tiamulin (< 0.001-0.125 mg/L). Our results demonstrate the genetic variability among M. hyopneumoniae isolates from pigs of the same farm, with differences in their susceptibility to antimicrobial agents.
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The prevalence of Salmonella in chelonians is not known in the UK and it is not clear whether such Salmonella strains would be pathogenic for human beings. Some strains, such as members of the Arizonae subgroup, may be unable to cause... more
The prevalence of Salmonella in chelonians is not known in the UK and it is not clear whether such Salmonella strains would be pathogenic for human beings. Some strains, such as members of the Arizonae subgroup, may be unable to cause anything more than very mild disease. To determine the carriage of Salmonella in pet tortoises, cloacal swabs were taken for culture. Salmonella enterica Group D was isolated from 5 of the 89 samples. All five were from the same household of seven tortoises. Salmonella isolates were shown by PCR to carry the invA and spiC genes associated with pathogenicity islands 1 and 2. Each isolate carried both genes indicating they had the genetic basis for disease and enterocyte invasion in human beings. The study indicates a low rate of asymptomatic carriage among the general population of pet tortoises. However, it does suggest that those Salmonella strains colonising the tortoise can carry Salmonellapathogenicity island (SPI)-1 and SPI-2 conferring the potent...