26
|
Baig A, Weinert LA, Peters SE, Howell KJ, Chaudhuri RR, Wang J, Holden MTG, Parkhill J, Langford PR, Rycroft AN, Wren BW, Tucker AW, Maskell DJ. Whole genome investigation of a divergent clade of the pathogen Streptococcus suis. Front Microbiol 2015; 6:1191. [PMID: 26583006 PMCID: PMC4631834 DOI: 10.3389/fmicb.2015.01191] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/12/2015] [Indexed: 11/23/2022] Open
Abstract
Streptococcus suis is a major porcine and zoonotic pathogen responsible for significant economic losses in the pig industry and an increasing number of human cases. Multiple isolates of S. suis show marked genomic diversity. Here, we report the analysis of whole genome sequences of nine pig isolates that caused disease typical of S. suis and had phenotypic characteristics of S. suis, but their genomes were divergent from those of many other S. suis isolates. Comparison of protein sequences predicted from divergent genomes with those from normal S. suis reduced the size of core genome from 793 to only 397 genes. Divergence was clear if phylogenetic analysis was performed on reduced core genes and MLST alleles. Phylogenies based on certain other genes (16S rRNA, sodA, recN, and cpn60) did not show divergence for all isolates, suggesting recombination between some divergent isolates with normal S. suis for these genes. Indeed, there is evidence of recent recombination between the divergent and normal S. suis genomes for 249 of 397 core genes. In addition, phylogenetic analysis based on the 16S rRNA gene and 132 genes that were conserved between the divergent isolates and representatives of the broader Streptococcus genus showed that divergent isolates were more closely related to S. suis. Six out of nine divergent isolates possessed a S. suis-like capsule region with variation in capsular gene sequences but the remaining three did not have a discrete capsule locus. The majority (40/70), of virulence-associated genes in normal S. suis were present in the divergent genomes. Overall, the divergent isolates extend the current diversity of S. suis species but the phenotypic similarities and the large amount of gene exchange with normal S. suis gives insufficient evidence to assign these isolates to a new species or subspecies. Further, sampling and whole genome analysis of more isolates is warranted to understand the diversity of the species.
Collapse
|
27
|
Bello-Ortí B, Howell KJ, Tucker AW, Maskell DJ, Aragon V. Metatranscriptomics reveals metabolic adaptation and induction of virulence factors by Haemophilus parasuis during lung infection. Vet Res 2015; 46:102. [PMID: 26395877 PMCID: PMC4580352 DOI: 10.1186/s13567-015-0225-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 07/21/2015] [Indexed: 01/08/2023] Open
Abstract
Haemophilus parasuis is a common inhabitant of the upper respiratory tract of pigs, and the causative agent of Glässer’s disease. This disease is characterized by polyserositis and arthritis, produced by the severe inflammation caused by the systemic spread of the bacterium. After an initial colonization of the upper respiratory tract, H. parasuis enters the lung during the early stages of pig infection. In order to study gene expression at this location, we sequenced the ex vivo and in vivo H. parasuis Nagasaki transcriptome in the lung using a metatranscriptomic approach. Comparison of gene expression under these conditions with that found in conventional plate culture showed generally reduced expression of genes associated with anabolic and catabolic pathways, coupled with up-regulation of membrane-related genes involved in carbon acquisition, iron binding and pathogenesis. Some of the up-regulated membrane genes, including ABC transporters, virulence-associated autotransporters (vtaAs) and several hypothetical proteins, were only present in virulent H. parasuis strains, highlighting their significance as markers of disease potential. Finally, the analysis also revealed the presence of numerous antisense transcripts with possible roles in gene regulation. In summary, this data sheds some light on the scarcely studied in vivo transcriptome of H. parasuis, revealing nutritional virulence as an adaptive strategy for host survival, besides induction of classical virulence factors.
Collapse
|
28
|
Zou G, Bello-Orti B, Aragon V, Tucker AW, Luo R, Ren P, Bi D, Zhou R, Jin H. The Cipher Code of Simple Sequence Repeats in "Vampire Pathogens". Sci Rep 2015. [PMID: 26215592 PMCID: PMC4516964 DOI: 10.1038/srep12441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Blood inside mammals is a forbidden area for the majority of prokaryotic microbes; however, red blood cells tropism microbes, like “vampire pathogens” (VP), succeed in matching scarce nutrients and surviving strong immunity reactions. Here, we found VP of Mycoplasma, Rhizobiales, and Rickettsiales showed significantly higher counts of (AG)n dimeric simple sequence repeats (Di-SSRs) in the genomes, coding and non-coding regions than non Vampire Pathogens (N_VP). Regression analysis indicated a significant correlation between GC content and the span of (AG)n-Di-SSR variation. Gene Ontology (GO) terms with abundance of (AG)3-Di-SSRs shared by the VP strains were associated with purine nucleotide metabolism (FDR < 0.01), indicating an adaptation to the limited availability of purine and nucleotide precursors in blood. Di-amino acids coded by (AG)n-Di-SSRs included all three six-fold code amino acids (Arg, Leu and Ser) and significantly higher counts of Di-amino acids coded by (AG)3, (GA)3, and (TC)3 in VP than N_VP. Furthermore, significant differences (P < 0.001) on the numbers of triplexes formed from (AG)n-Di-SSRs between VP and N_VP in Mycoplasma suggested the potential role of (AG)n-Di-SSRs in gene regulation.
Collapse
|
29
|
Shan J, Tucker AW, Gaalaas LR, Wu G, Platin E, Mol A, Lu J, Zhou O. Stationary intraoral digital tomosynthesis using a carbon nanotube X-ray source array. Dentomaxillofac Radiol 2015; 44:20150098. [PMID: 26090933 PMCID: PMC5120569 DOI: 10.1259/dmfr.20150098] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 06/09/2015] [Accepted: 06/17/2015] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES Intraoral dental tomosynthesis and closely related tuned-aperture CT (TACT) are low-dose three-dimensional (3D) imaging modalities that have shown improved detection of multiple dental diseases. Clinical interest in implementing these technologies waned owing to their time-consuming nature. Recently developed carbon nanotube (CNT) X-ray sources allow rapid multi-image acquisition without mechanical motion, making tomosynthesis a clinically viable technique. The objective of this investigation was to evaluate the feasibility of and produce high-quality images from a digital tomosynthesis system employing CNT X-ray technology. METHODS A test-bed stationary intraoral tomosynthesis unit was constructed using a CNT X-ray source array and a digital intraoral sensor. The source-to-image distance was modified to make the system comparable in image resolution to current two-dimensional intraoral radiography imaging systems. Anthropomorphic phantoms containing teeth with simulated and real caries lesions were imaged using a dose comparable to D-speed film dose with a rectangular collimation. Images were reconstructed and analysed. RESULTS Tomosynthesis images of the phantom and teeth specimen demonstrated perceived image quality equivalent or superior to standard digital images with the added benefit of 3D information. The ability to "scroll" through slices in a buccal-lingual direction significantly improved visualization of anatomical details. In addition, the subjective visibility of dental caries was increased. CONCLUSIONS Feasibility of the stationary intraoral tomosynthesis is demonstrated. The results show clinical promise and suitability for more robust observer and clinical studies.
Collapse
MESH Headings
- Alveolar Process/diagnostic imaging
- Dental Caries/diagnostic imaging
- Dental Materials/chemistry
- Dental Restoration, Permanent
- Feasibility Studies
- Humans
- Image Processing, Computer-Assisted/methods
- Imaging, Three-Dimensional/methods
- Maxilla/diagnostic imaging
- Nanotubes, Carbon
- Phantoms, Imaging
- Radiation Dosage
- Radiographic Image Enhancement/methods
- Radiography, Dental, Digital/instrumentation
- Radiography, Dental, Digital/methods
- Tomography, X-Ray Computed/instrumentation
- Tomography, X-Ray Computed/methods
- Tooth/diagnostic imaging
- X-Ray Film
Collapse
|
30
|
Bossé JT, Li Y, Atherton TG, Walker S, Williamson SM, Rogers J, Chaudhuri RR, Weinert LA, Holden MTG, Maskell DJ, Tucker AW, Wren BW, Rycroft AN, Langford PR. Characterisation of a mobilisable plasmid conferring florfenicol and chloramphenicol resistance in Actinobacillus pleuropneumoniae. Vet Microbiol 2015; 178:279-82. [PMID: 26049592 PMCID: PMC4503812 DOI: 10.1016/j.vetmic.2015.05.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 05/22/2015] [Accepted: 05/25/2015] [Indexed: 12/02/2022]
Abstract
First complete sequence of a floR plasmid from Actinobacillus pleuropneumoniae Extended similarity to floR plasmids in other Pasteurellaceae species Conjugal transfer between between species confirmed
The complete nucleotide sequence of a 7.7 kb mobilisable plasmid (pM3446F), isolated from a florfenicol resistant isolate of Actinobacillus pleuropneumoniae, showed extended similarity to plasmids found in other members of the Pasteurellaceae containing the floR gene as well as replication and mobilisation genes. Mobilisation into other Pasteurellaceae species confirmed that this plasmid can be transferred horizontally.
Collapse
|
31
|
Bossé JT, Li Y, Walker S, Atherton T, Fernandez Crespo R, Williamson SM, Rogers J, Chaudhuri RR, Weinert LA, Oshota O, Holden MTG, Maskell DJ, Tucker AW, Wren BW, Rycroft AN, Langford PR. Identification of dfrA14 in two distinct plasmids conferring trimethoprim resistance in Actinobacillus pleuropneumoniae. J Antimicrob Chemother 2015; 70:2217-22. [PMID: 25957382 PMCID: PMC4500777 DOI: 10.1093/jac/dkv121] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 04/05/2015] [Indexed: 11/30/2022] Open
Abstract
Objectives The objective of this study was to determine the distribution and genetic basis of trimethoprim resistance in Actinobacillus pleuropneumoniae isolates from pigs in England. Methods Clinical isolates collected between 1998 and 2011 were tested for resistance to trimethoprim and sulphonamide. The genetic basis of trimethoprim resistance was determined by shotgun WGS analysis and the subsequent isolation and sequencing of plasmids. Results A total of 16 (out of 106) A. pleuropneumoniae isolates were resistant to both trimethoprim (MIC >32 mg/L) and sulfisoxazole (MIC ≥256 mg/L), and a further 32 were resistant only to sulfisoxazole (MIC ≥256 mg/L). Genome sequence data for the trimethoprim-resistant isolates revealed the presence of the dfrA14 dihydrofolate reductase gene. The distribution of plasmid sequences in multiple contigs suggested the presence of two distinct dfrA14-containing plasmids in different isolates, which was confirmed by plasmid isolation and sequencing. Both plasmids encoded mobilization genes, the sulphonamide resistance gene sul2, as well as dfrA14 inserted into strA, a streptomycin-resistance-associated gene, although the gene order differed between the two plasmids. One of the plasmids further encoded the strB streptomycin-resistance-associated gene. Conclusions This is the first description of mobilizable plasmids conferring trimethoprim resistance in A. pleuropneumoniae and, to our knowledge, the first report of dfrA14 in any member of the Pasteurellaceae. The identification of dfrA14 conferring trimethoprim resistance in A. pleuropneumoniae isolates will facilitate PCR screens for resistance to this important antimicrobial.
Collapse
|
32
|
Howell KJ, Weinert LA, Chaudhuri RR, Luan SL, Peters SE, Corander J, Harris D, Angen Ø, Aragon V, Bensaid A, Williamson SM, Parkhill J, Langford PR, Rycroft AN, Wren BW, Holden MTG, Tucker AW, Maskell DJ. The use of genome wide association methods to investigate pathogenicity, population structure and serovar in Haemophilus parasuis. BMC Genomics 2014; 15:1179. [PMID: 25539682 PMCID: PMC4532294 DOI: 10.1186/1471-2164-15-1179] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 12/12/2014] [Indexed: 01/06/2023] Open
Abstract
Background Haemophilus parasuis is the etiologic agent of Glässer’s disease in pigs and causes devastating losses to the farming industry. Whilst some hyper-virulent isolates have been described, the relationship between genetics and disease outcome has been only partially established. In particular, there is weak correlation between serovar and disease phenotype. We sequenced the genomes of 212 isolates of H. parasuis and have used this to describe the pan-genome and to correlate this with clinical and carrier status, as well as with serotype. Results Recombination and population structure analyses identified five groups with very high rates of recombination, separated into two clades of H. parasuis with no signs of recombination between them. We used genome-wide association methods including discriminant analysis of principal components (DAPC) and generalised linear modelling (glm) to look for genetic determinants of this population partition, serovar and pathogenicity. We were able to identify genes from the accessory genome that were significantly associated with phenotypes such as potential serovar specific genes including capsule genes, and 48 putative virulence factors that were significantly different between the clinical and non-clinical isolates. We also show that the presence of many previously suggested virulence factors is not an appropriate marker of virulence. Conclusions These genes will inform the generation of new molecular diagnostics and vaccines, and refinement of existing typing schemes and show the importance of the accessory genome of a diverse species when investigating the relationship between genotypes and phenotypes. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1179) contains supplementary material, which is available to authorized users.
Collapse
|
33
|
Bello-Ortí B, Deslandes V, Tremblay YDN, Labrie J, Howell KJ, Tucker AW, Maskell DJ, Aragon V, Jacques M. Biofilm formation by virulent and non-virulent strains of Haemophilus parasuis. Vet Res 2014; 45:104. [PMID: 25428823 PMCID: PMC4245831 DOI: 10.1186/s13567-014-0104-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 09/26/2014] [Indexed: 01/09/2023] Open
Abstract
Haemophilus parasuis is a commensal bacterium of the upper respiratory tract of healthy pigs. It is also the etiological agent of Glässer’s disease, a systemic disease characterized by polyarthritis, fibrinous polyserositis and meningitis, which causes high morbidity and mortality in piglets. The aim of this study was to evaluate biofilm formation by well-characterized virulent and non-virulent strains of H. parasuis. We observed that non-virulent strains isolated from the nasal cavities of healthy pigs formed significantly (p < 0.05) more biofilms than virulent strains isolated from lesions of pigs with Glässer’s disease. These differences were observed when biofilms were formed in microtiter plates under static conditions or formed in the presence of shear force in a drip-flow apparatus or a microfluidic system. Confocal laser scanning microscopy using different fluorescent probes on a representative subset of strains indicated that the biofilm matrix contains poly-N-acetylglucosamine, proteins and eDNA. The biofilm matrix was highly sensitive to degradation by proteinase K. Comparison of transcriptional profiles of biofilm and planktonic cells of the non-virulent H. parasuis F9 strain revealed a significant number of up-regulated membrane-related genes in biofilms, and genes previously identified in Actinobacillus pleuropneumoniae biofilms. Our data indicate that non-virulent strains of H. parasuis have the ability to form robust biofilms in contrast to virulent, systemic strains. Biofilm formation might therefore allow the non-virulent strains to colonize and persist in the upper respiratory tract of pigs. Conversely, the planktonic state of the virulent strains might allow them to disseminate within the host.
Collapse
|
34
|
Butler BJ, Bo C, Tucker AW, Jardine AP, Proud WG, Williams A, Brown KA. Mechanical and histological characterization of trachea tissue subjected to blast-type pressures. ACTA ACUST UNITED AC 2014. [DOI: 10.1088/1742-6596/500/18/182007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
35
|
Maglennon GA, Cook BS, Deeney AS, Bossé JT, Peters SE, Langford PR, Maskell DJ, Tucker AW, Wren BW, Rycroft AN. Transposon mutagenesis in Mycoplasma hyopneumoniae using a novel mariner-based system for generating random mutations. Vet Res 2013; 44:124. [PMID: 24359443 PMCID: PMC4028751 DOI: 10.1186/1297-9716-44-124] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 12/02/2013] [Indexed: 11/10/2022] Open
Abstract
Mycoplasma hyopneumoniae is the cause of enzootic pneumonia in pigs, a chronic respiratory disease associated with significant economic losses to swine producers worldwide. The molecular pathogenesis of infection is poorly understood due to the lack of genetic tools to allow manipulation of the organism and more generally for the Mycoplasma genus. The objective of this study was to develop a system for generating random transposon insertion mutants in M. hyopneumoniae that could prove a powerful tool in enabling the pathogenesis of infection to be unraveled. A novel delivery vector was constructed containing a hyperactive C9 mutant of the Himar1 transposase along with a mini transposon containing the tetracycline resistance cassette, tetM. M. hyopneumoniae strain 232 was electroporated with the construct and tetM-expressing transformants selected on agar containing tetracycline. Individual transformants contained single transposon insertions that were stable upon serial passages in broth medium. The insertion sites of 44 individual transformants were determined and confirmed disruption of several M. hyopneumoniae genes. A large pool of over 10 000 mutants was generated that should allow saturation of the M. hyopneumoniae strain 232 genome. This is the first time that transposon mutagenesis has been demonstrated in this important pathogen and could be generally applied for other Mycoplasma species that are intractable to genetic manipulation. The ability to generate random mutant libraries is a powerful tool in the further study of the pathogenesis of this important swine pathogen.
Collapse
|
36
|
Maglennon GA, Cook BS, Matthews D, Deeney AS, Bossé JT, Langford PR, Maskell DJ, Tucker AW, Wren BW, Rycroft AN. Development of a self-replicating plasmid system for Mycoplasma hyopneumoniae. Vet Res 2013; 44:63. [PMID: 23895236 PMCID: PMC3765554 DOI: 10.1186/1297-9716-44-63] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 07/10/2013] [Indexed: 11/13/2022] Open
Abstract
Mycoplasma hyopneumoniae is a prevalent swine respiratory pathogen that is a major cause of economic loss to pig producers. Control is achieved by a combination of antimicrobials, vaccination and management practices, but current vaccines offer only partial control and there is a need for improved preventative strategies. A major barrier to advances in understanding the pathogenesis of M. hyopneumoniae and in developing new vaccines is the lack of tools to genetically manipulate the organism. We describe the development and optimisation of the first successful plasmid-based system for the genetic manipulation of M. hyopneumoniae. Our artificial plasmids contain the origin of replication (oriC) of M. hyopneumoniae along with tetM, conferring resistance to tetracycline. With these plasmids, we have successfully transformed M. hyopneumoniae strain 232 by electroporation, generating tetracycline resistant organisms. The persistence of extrachromosomal plasmid and maintenance of plasmid DNA over serial passages shows that these artificial plasmids are capable of self-replication in M. hyopneumoniae. In addition to demonstrating the amenability of M. hyopneumoniae to genetic manipulation and in optimising the conditions necessary for successful transformation, we have used this system to determine the minimum functional oriC of M. hyopneumoniae. In doing so, we have developed a plasmid with a small oriC that is stably maintained over multiple passages that may be useful in generating targeted gene disruptions. In conclusion, we have generated a set of plasmids that will be valuable in studies of M. hyopneumoniae pathogenesis and provide a major step forward in the study of this important swine pathogen.
Collapse
|
37
|
Luan SL, Chaudhuri RR, Peters SE, Mayho M, Weinert LA, Crowther SA, Wang J, Langford PR, Rycroft A, Wren BW, Tucker AW, Maskell DJ. Generation of a Tn5 transposon library in Haemophilus parasuis and analysis by transposon-directed insertion-site sequencing (TraDIS). Vet Microbiol 2013; 166:558-66. [PMID: 23928120 DOI: 10.1016/j.vetmic.2013.07.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 07/11/2013] [Accepted: 07/12/2013] [Indexed: 10/26/2022]
Abstract
Haemophilus parasuis is an important respiratory tract pathogen of swine and the etiological agent of Glässer's disease. The molecular pathogenesis of H. parasuis is not well studied, mainly due to the lack of efficient tools for genetic manipulation of this bacterium. In this study we describe a Tn5-based random mutagenesis method for use in H. parasuis. A novel chloramphenicol-resistant Tn5 transposome was electroporated into the virulent H. parasuis serovar 5 strain 29755. High transposition efficiency of Tn5, up to 10(4) transformants/μg of transposon DNA, was obtained by modification of the Tn5 DNA in the H. parasuis strain HS071 and establishment of optimal electrotransformation conditions, and a library of approximately 10,500 mutants was constructed. Analysis of the library using transposon-directed insertion-site sequencing (TraDIS) revealed that the insertion of Tn5 was evenly distributed throughout the genome. 10,001 individual mutants were identified, with 1561 genes being disrupted (69.4% of the genome). This newly-developed, efficient mutagenesis approach will be a powerful tool for genetic manipulation of H. parasuis in order to study its physiology and pathogenesis.
Collapse
|
38
|
Jäger HC, McKinley TJ, Wood JLN, Pearce GP, Williamson S, Strugnell B, Done S, Habernoll H, Palzer A, Tucker AW. Factors associated with pleurisy in pigs: a case-control analysis of slaughter pig data for England and Wales. PLoS One 2012; 7:e29655. [PMID: 22363407 PMCID: PMC3281815 DOI: 10.1371/journal.pone.0029655] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 12/01/2011] [Indexed: 11/18/2022] Open
Abstract
A case-control investigation was undertaken to determine management and health related factors associated with pleurisy in slaughter pigs in England and Wales. Methods The British Pig Executive Pig Health Scheme database of abattoir pathology was used to identify 121 case (>10% prevalence of pleurisy on 3 or more assessment dates in the preceding 24 months) and 121 control units (≤5% prevalence of pleurisy on 3 or more assessment dates in the preceding 24 months). Farm data were collected by postal questionnaire. Data from respondents (70 cases and 51 controls) were analysed using simple logistic regression models with Bonferroni corrections. Limited multivariate analyses were also performed to check the robustness of the overall conclusions. Results and Conclusions Management factors associated with increased odds of pleurisy included no all-in all-out pig flow (OR 9.3, 95% confidence interval [CI]: 3.3–29), rearing of pigs with an age difference of >1 month in the same airspace (OR 6.5 [2.8–17]) and repeated mixing (OR 2.2 [1.4–3.8]) or moving (OR 2.2 [1.5–3.4]) of pigs during the rearing phase. Those associated with decreased odds of pleurisy included filling wean-to-finish or grower-to-finish systems with piglets from ≤3 sources (OR 0.18 [0.07–0.41]) compared to farrow-to-finish systems, cleaning and disinfecting of grower (ORs 0.28 [0.13–0.61] and 0.29 [0.13–0.61]) and finisher (ORs 0.24 [0.11–0.51] and 0.2 [0.09–0.44]) accommodation between groups, and extended down time of grower and finisher accommodation (OR 0.84 [0.75–0.93] and 0.86 [0.77–0.94] respectively for each additional day of downtime). This study demonstrated the value of national-level abattoir pathology data collection systems for case control analyses and generated guidance for on-farm interventions to help reduce the prevalence of pleurisy in slaughter pigs.
Collapse
|
39
|
Wilkinson JM, Sargent CA, Galina-Pantoja L, Tucker AW. Gene expression profiling in the lungs of pigs with different susceptibilities to Glässer's disease. BMC Genomics 2010; 11:455. [PMID: 20670446 PMCID: PMC3017779 DOI: 10.1186/1471-2164-11-455] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Accepted: 07/29/2010] [Indexed: 01/07/2023] Open
Abstract
Background Haemophilus parasuis is the causative agent of Glässer's disease in pigs. Currently, little is known about the molecular mechanisms that contribute to disease susceptibility. This study used a porcine oligonucleotide microarray to identify genes that were differentially expressed (DE) in the lungs of colostrum-deprived animals previously characterized as being either 'Fully Resistant' (FR) or 'Susceptible' to infection by H. parasuis in a bacterial challenge experiment. Results Gene expression profiles of 'FR' and 'Susceptible' animals were obtained by the identification of genes that were differentially expressed between each of these groups and mock-inoculated 'Control' animals. At 24 hours post-inoculation, a total of 21 and 58 DE genes were identified in 'FR' and 'Susceptible' animals respectively. At 72 hours, the numbers of genes were 20 and 347 respectively. 'FR' animals at 24 hours exhibited an increased expression of genes encoding extracellular matrix and TGF-β signalling components, possibly indicative of tissue repair following the successful early resolution of infection. The gene expression profile of 'FR' animals at 72 hours supported the hypothesis that higher levels of antibacterial activity were responsible for the 'FR' phenotype, possibly due to an increase in natural immunoglobulin A and decrease in signalling by the immunoregulatory transcription factor peroxisome proliferator-activated receptor gamma (PPAR-γ). The expression profile of 'Susceptible' animals at both time-points was characterized by an imbalance in signalling between pro and anti-inflammatory cytokines and an increased expression of genes involved in biological processes associated with inflammation. These include the pro-inflammatory cytokine genes resistin (RETN) and interleukin 1-beta (IL1B). At 72 hours, a reduction in the expression of genes involved in antigen presentation by both MHC class I and II molecules was observed, which could have contributed to the inability of 'Susceptible' animals to clear infection. Conclusions This study is the first to have identified discrete sets of DE genes in pigs of differing susceptibility to H. parasuis infection. Consequently, several candidate genes and pathways for disease resistance or susceptibility phenotypes have been identified. In addition, the findings have shed light on the molecular pathology associated with Glässer's disease.
Collapse
|
40
|
Nunes SF, Murcia PR, Tiley LS, Brown IH, Tucker AW, Maskell DJ, Wood JLN. An ex vivo swine tracheal organ culture for the study of influenza infection. Influenza Other Respir Viruses 2010; 4:7-15. [PMID: 20021502 PMCID: PMC4941949 DOI: 10.1111/j.1750-2659.2009.00119.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Background The threat posed by swine influenza viruses with potential to transmit from pig populations to other hosts, including humans, requires the development of new experimental systems to study different aspects of influenza infection. Ex vivo organ culture (EVOC) systems have been successfully used in the study of both human and animal respiratory pathogens. Objectives We aimed to develop an air interface EVOC using pig tracheas in the study of influenza infection demonstrating that tracheal explants can be effectively maintained in organ culture and support productive influenza infection. Methods Tracheal explants were maintained in the air interface EVOC system for 7 days. Histological characteristics were analysed with different staining protocols and co‐ordinated ciliary movement on the epithelial surface was evaluated through a bead clearance assay. Explants were infected with a swine H1N1 influenza virus. Influenza infection of epithelial cells was confirmed by immunohistochemistry and viral replication was quantified by plaque assays and real‐time RT‐PCR. Results Histological analysis and bead clearance assay showed that the tissue architecture of the explants was maintained for up to 7 days, while ciliary movement exhibited a gradual decrease after 4 days. Challenge with swine H1N1 influenza virus showed that the EVOC tracheal system shows histological changes consistent with in vivo influenza infection and supported productive viral replication over multiple cycles of infection. Conclusion The air interface EVOC system using pig trachea described here constitutes a useful biological tool with a wide range of applications in the study of influenza infection.
Collapse
|
41
|
Lucianez A, Holmes MA, Tucker AW. Relationships between processing delay and microbial load of broiler neck skin samples. J Food Prot 2010; 73:26-31. [PMID: 20051200 DOI: 10.4315/0362-028x-73.1.26] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The measurable microbial load on poultry carcasses during processing is determined by a number of factors including farm or origin, processing hygiene, and external temperature. This study investigated associations between carcass microbial load and progressive delays to processing. A total of 30 carcasses were delayed immediately after defeathering and before evisceration in a commercial abattoir in groups of five, and were held at ambient temperature for 1, 2, 3, 4, 6, and 8 h. Delayed carcasses were reintroduced to the processing line, and quantitative assessment of total viable count, coliforms, Staphylococcus aureus, and Pseudomonas spp. was undertaken on neck skin flap samples collected after carcass chilling and then pooled for each group. Sampling was repeated on 5 separate days, and the data were combined. Significant increases in total viable count (P = 0.001) and coliforms (P = 0.004), but not for S. aureus or Pseudomonas loads, were observed across the 8-h period of delay. In line with previous studies, there was significant variation in microbiological data according to sampling day. In conclusion, there is a significant and measurable decline in microbiological status of uneviscerated but defeathered poultry carcasses after an 8-h delay, but the variability of sampling results, reflecting the wide range of factors that impact microbial load, means that it is not possible to determine maximum or minimum acceptable periods of processing delay based on this criterion alone.
Collapse
|
42
|
Niesalla HS, Dale A, Slater JD, Scholes SFE, Archer J, Maskell DJ, Tucker AW. Critical assessment of an in vitro bovine respiratory organ culture system: a model of bovine herpesvirus-1 infection. J Virol Methods 2009; 158:123-9. [PMID: 19428580 DOI: 10.1016/j.jviromet.2009.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 02/03/2009] [Accepted: 02/05/2009] [Indexed: 11/16/2022]
Abstract
A bovine in vitro organ culture (BIVOC) system was evaluated as a model to study host and pathogen events during the course of bovine herpesvirus-1 infection. Upper respiratory tract epithelium, from slaughtered animals, was cultured in an air-liquid interface system and integrity, viability, and TNF-alpha gene expression of tissue explants were monitored over 72h in the presence or absence of infection by bovine herpesvirus type 1 (BHV-1). Uninfected explants maintained viability and integrity over the 72h time course although histological signs of degeneration were first visible from 24h of culture. Explants were productively infected with BHV-1 and typical, dose dependent, cytopathic changes were observed in response to infection. Regulation of TNF-alpha gene expression in uninfected explants varied over time and was region-specific but there was significant down-regulation of TNF-alpha gene expression at 2h post-infection when compared to uninfected controls at the same time point. Taking caveats into consideration the BIVOC system shows promise as a tool for analysis of immediate or early events in host-pathogen interaction.
Collapse
|
43
|
Grierson SS, King DP, Tucker AW, Donadeu M, Mellencamp MA, Haverson K, Banks M, Bailey M. Ontogeny of systemic cellular immunity in the neonatal pig: Correlation with the development of post-weaning multisystemic wasting syndrome. Vet Immunol Immunopathol 2007; 119:254-68. [PMID: 17629574 DOI: 10.1016/j.vetimm.2007.06.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Revised: 04/30/2007] [Accepted: 06/04/2007] [Indexed: 11/19/2022]
Abstract
The aetiology of porcine post-weaning multisystemic wasting syndrome (PMWS) is poorly understood. Porcine circovirus type 2 (PCV-2) is an essential component of the experimental disease model for PMWS: however, evidence from experimental and field studies indicates that additional factors play a critical role in the aetiopathogenesis of PMWS. Current candidates include (1) immune stimulation (for example, via co-infection or vaccination), and (2) a novel infectious agent. A prospective, longitudinal case-control study was designed to investigate molecular triggers in leucocytes of neonatal piglets that may predispose to the development of PMWS. Blood samples were collected weekly from pigs (n=125) within five farms, from 1 week to 8 weeks of age: that is, before the appearance of clinical signs. Four colour flow cytometry was used to investigate changes in subsets of peripheral blood mononuclear cells, using monoclonal antibodies against the following cell associated markers; sIgG, CD3, MHCII dR, CD14, CD4a, CD8a, CD45RC, CD25, SWC3a, SWC8, CD163 and CD45. Sampling and laboratory analysis was supported by monitoring of clinical signs from 1 week to 20 weeks of age, or until disease supervened. At the conclusion of the study, 68 pigs (54%) were classified in Group 1 (no signs of clinical disease), 34 pigs (27%) in Group 2 (signs of clinical disease but not characteristic of PMWS), 17 pigs (14%) in Group 3 (suspect PMWS case) and 5 pigs (4%) in Group 4 (PMWS case). A single case of Porcine Dermatitis and Nephropathy syndrome (PDNS) was also diagnosed. Significant changes with age were demonstrated in clinically normal, neonatal pigs (Group 1), including an increase in B-cells and T-cells, and an increase in the proportion of total T-cells expressing MHCII. Within the T-cell subset, the proportion of CD8(+high) CD4(-) T-cells increased, in addition to the proportion of CD4(+) T-cells co-expressing CD8. Of the factors recorded, farm was found to have a highly significant effect on immune system development in the neonate. Comparison of Groups 1 and 4 cases identified significant differences between pigs which remained normal and those which subsequently developed PMWS. Pigs which went on to develop PMWS had a greater proportion of T-cells expressing MHCII in early life, higher mean intensity of expression of MHCII on T-cells, higher mean intensity of expression of MHCII on B cells and higher expression of CD25 on CD45RC(-) T-cells. These findings suggest that lymphocyte activation may be a key early event in the aetiology of PMWS.
Collapse
|
44
|
de la Fuente AJM, Tucker AW, Navas J, Blanco M, Morris SJ, Gutiérrez-Martín CB. Antimicrobial susceptibility patterns of Haemophilus parasuis from pigs in the United Kingdom and Spain. Vet Microbiol 2007; 120:184-91. [PMID: 17110059 DOI: 10.1016/j.vetmic.2006.10.014] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 10/02/2006] [Accepted: 10/10/2006] [Indexed: 11/25/2022]
Abstract
A total of 30 British and 30 Spanish Haemophilus parasuis isolates were tested for their susceptibility to 19 of the antimicrobials currently used in swine practice with a broth microdilution method in order to know the emergence of resistance against these compounds in this porcine pathogen. All the British isolates were susceptible to penicillin, ceftiofur, erythromycin, tilmicosin, enrofloxacin, and florfenicol, and most of them were susceptible to the remaining antimicrobials (the highest resistance rate found was of 20% to neomycin). In contrast, all the Spanish isolates were susceptible exclusively to florfenicol, and high proportions of resistance were encountered for penicillin, ampicillin, oxytetracycline, erythromycin, tilmicosin, tiamulin and trimethoprim+sulphamethoxazole; in addition, a bimodal or multimodal distribution, or tailing of Spanish isolates over the MIC range was observed for clindamycin, sulphonamides and tylosine tartrate, suggesting the development of acquired resistance. In addition, several multiresistance patterns were found among the Spanish isolates, 23.3% of them being resistant to at least eight antimicrobials, the same rate as that encountered for those being susceptible to all antimicrobials tested. This study showed that in general British H. parasuis isolates are susceptible to antimicrobial agents routinely used for treatment of porcine respiratory diseases; however, the Spanish isolates need a more continuous surveillance of their susceptibility patterns.
Collapse
|
45
|
|
46
|
Tucker AW, Foweraker JE, Belcher CE, Moloo B, Bell JA, Humar A, Mazzulli T, Grant D. Control of microbial contamination during surgical harvest of pig renal xenografts. Xenotransplantation 2004; 11:91-6. [PMID: 14962297 DOI: 10.1111/j.1399-3089.2004.00090.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The pig has been identified as the most likely source of xenograft material for clinical use and studies are ongoing to overcome the immunological hurdles of pig-to-human transplantation. Attention is now being focussed on identifying and reducing the potential microbiological hazards associated with this technique. Studies have primarily addressed issues surrounding the production and health monitoring of xenograft source pigs and none have so far specifically evaluated the possible risks of microbial contamination during xenograft harvest. In this report, we evaluate the possible routes for contamination of a pig kidney xenograft during organ harvest and describe approaches to the control of these hazards, including the novel use of a custom designed airtight surgical canopy. A standard procedure for microbiological monitoring during xenograft harvest was devised and evaluated. This allowed the rapid identification and anti-microbial sensitivity testing of any isolated organisms. This would enable an early and appropriate pre-emptive treatment of infection because of transmission of pig micro-organisms.
Collapse
|
47
|
Tucker AW, McNeilly F, Meehan B, Galbraith D, McArdle PD, Allan G, Patience C. Methods for the exclusion of circoviruses and gammaherpesviruses from pigs. Xenotransplantation 2003; 10:343-8. [PMID: 12795683 DOI: 10.1034/j.1399-3089.2003.02048.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The use of porcine tissues is being developed as a means to alleviate the shortage of allogeneic tissues and organs available for transplantation. To reduce the possibility of a microorganism of pigs being inadvertently transferred to the recipient of the xenograft, recommendations have been published on the microbiological specifications for organ source pigs. The porcine circoviruses (PCV1 and PCV2) and porcine lymphotropic herpesviruses (PLHV1 and PLHV2) are two infectious agents of pigs which are considered to be of significance for the microbiological safety of xenotransplantation. To ensure the exclusion of these microorganisms from animals destined for use under clinical conditions, reliable breeding methodologies are required. We investigated the efficiency of established derivation procedures for the removal of PCV and PLHV. In comparison with conventionally reared pigs, caesarian and barrier derived animals showed a markedly reduced prevalence of PCVs and PLHVs. Our results indicate that the derivation of animals free of both of these microorganisms is achievable and will enhance the microbiological safety of xenotransplantation.
Collapse
|
48
|
Clark DA, Fryer JFL, Tucker AW, McArdle PD, Hughes AE, Emery VC, Griffiths PD. Porcine cytomegalovirus in pigs being bred for xenograft organs: progress towards control. Xenotransplantation 2003; 10:142-8. [PMID: 12588647 DOI: 10.1034/j.1399-3089.2003.01128.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In human medicine, human cytomegalovirus (HCMV) is readily transmitted by organ transplant causing end-organ disease and triggering graft rejection in recipients. Because of a chronic shortage of human organs, pigs transgenic for human complement control proteins are being considered as potential donors. Such xenotransplantation raises concerns about the potential zoonotic transmission of viruses including porcine cytomegalovirus (PCMV), an endemic infection of pigs. Similar to HCMV and PCMV transmission is thought to occur in utero and perinatally. We used quantitative polymerase chain reaction to examine the prevalence, organ distribution and viral load of PCMV in human decay accelerating factor (CD55) transgenic pigs. In animals reared under conventional farm conditions, virus was identified in a wide range of organs including potential xenografts (liver, kidney and heart). The spleen was PCMV DNA positive in all infected pigs. Examination of foetal spleens failed to identify evidence of transplacental infection and prospective monitoring of two litters showed that infection occurred in the postnatal period. This transmission was prevented by hysterotomy derivation and barrier rearing. Our findings demonstrate that PCMV could be eradicated from pig herds being bred for xenotransplantation and argue that the spleen from donor animals should be examined as part of quality control procedures if clinical trials proceed.
Collapse
|
49
|
Tucker AW, Isaacs D, Burgess M. Cost-effectiveness analysis of changing from live oral poliovirus vaccine to inactivated poliovirus vaccine in Australia. Aust N Z J Public Health 2001; 25:411-6. [PMID: 11688618 DOI: 10.1111/j.1467-842x.2001.tb00648.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
OBJECTIVE Estimate the economic impact of introducing inactivated poliovirus vaccine (IPV) into the Australian childhood immunisation schedule to eliminate vaccine-associated paralytic poliomyelitis (VAPP). METHODS Cost-effectiveness of two different four-dose IPV schedules (monovalent vaccine and IPV-containing combination vaccine) compared with the current four-dose oral poliovirus vaccine (OPV) schedule for Australian children through age six years. Model used estimates of VAPP incidence, costs, and vaccine utilisation and price obtained from published and unpublished sources. Main outcome measures were total costs, outcomes prevented, and incremental cost-effectiveness, expressed as net cost per case of VAPP prevented. RESULTS Changing to an IPV-based schedule would prevent 0.395 VAPP cases annually. At $20 per dose for monovalent vaccine and $14 per dose for the IPV component in a combination vaccine, the change would incur incremental, annual costs of $19.5 million ($49.3 million per VAPP case prevented) and $6.7 million ($17.0 million per VAPP case prevented), respectively. Threshold analysis identified break-even prices per dose of $1 for monovalent and $7 for combination vaccines. CONCLUSIONS Introducing IPV into the Australian childhood immunisation schedule is not likely to be cost-effective unless it comes in a combined vaccine with the IPV-component price below $10. IMPLICATIONS More precise estimates of VAPP incidence in Australia and IPV price are needed. However, poor cost-effectiveness will make the decision about switching from OPV to IPV in the childhood schedule difficult.
Collapse
|
50
|
Tucker AW, Maillet JO, Linial GT. Graduate education in clinical systems: distance learning in an emerging field. AMERICAN CLINICAL LABORATORY 1999; 18:4. [PMID: 10848430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
|