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Ruth M Kennan - One of the best experts on this subject based on the ideXlab platform.

  • a two component regulatory system modulates twitching motility in Dichelobacter Nodosus
    Veterinary Microbiology, 2015
    Co-Authors: Dane Parker, Ruth M Kennan, Lynne Turnbull, Carrie J Lovitt, Xiaoyan Han, Cynthia B Whitchurch
    Abstract:

    Dichelobacter Nodosus is the essential causative agent of footrot in sheep and type IV fimbriae-mediated twitching motility has been shown to be essential for virulence. We have identified a two-component signal transduction system (TwmSR) that shows similarity to chemosensory systems from other bacteria. Insertional inactivation of the gene encoding the response regulator, TwmR, led to a twitching motility defect, with the mutant having a reduced rate of twitching motility when compared to the wild-type and a mutant complemented with the wild-type twmR gene. The reduced rate of twitching motility was not a consequence of a reduced growth rate or decreased production of surface located fimbriae, but video microscopy indicated that it appeared to result from an overall loss of twitching directionality. These results suggest that a chemotactic response to environmental factors may play an important role in the D. Nodosus-mediated disease process.

  • genomic evidence for a globally distributed bimodal population in the ovine footrot pathogen Dichelobacter Nodosus
    Mbio, 2014
    Co-Authors: Ruth M Kennan, Om P Dhungyel, Richard Whittington, Sara Frosth, Torsten Seemann, Marianne Gilhuus
    Abstract:

    ABSTRACT Footrot is a contagious, debilitating disease of sheep, causing major economic losses in most sheep-producing countries. The causative agent is the Gram-negative anaerobe Dichelobacter Nodosus. Depending on the virulence of the infective bacterial strain, clinical signs vary from a mild interdigital dermatitis (benign footrot) to severe underrunning of the horn of the hoof (virulent footrot). The aim of this study was to investigate the genetic relationship between D. Nodosus strains of different phenotypic virulences and between isolates from different geographic regions. Genome sequencing was performed on 103 D. Nodosus isolates from eight different countries. Comparison of these genome sequences revealed that they were highly conserved, with >95% sequence identity. However, single nucleotide polymorphism analysis of the 31,627 nucleotides that were found to differ in one or more of the 103 sequenced isolates divided them into two distinct clades. Remarkably, this division correlated with known virulent and benign phenotypes, as well as with the single amino acid difference between the AprV2 and AprB2 proteases, which are produced by virulent and benign strains, respectively. This division was irrespective of the geographic origin of the isolates. However, within one of these clades, isolates from different geographic regions generally belonged to separate clusters. In summary, we have shown that D. Nodosus has a bimodal population structure that is globally conserved and provide evidence that virulent and benign isolates represent two distinct forms of D. Nodosus strains. These data have the potential to improve the diagnosis and targeted control of this economically significant disease. IMPORTANCE The Gram-negative anaerobic bacterium Dichelobacter Nodosus is the causative agent of ovine footrot, a disease of major importance to the worldwide sheep industry. The known D. Nodosus virulence factors are its type IV fimbriae and extracellular serine proteases. D. Nodosus strains are designated virulent or benign based on the type of disease caused under optimal climatic conditions. These isolates have similar fimbriae but distinct extracellular proteases. To determine the relationship between virulent and benign isolates and the relationship of isolates from different geographical regions, a genomic study that involved the sequencing and subsequent analysis of 103 D. Nodosus isolates was undertaken. The results showed that D. Nodosus isolates are highly conserved at the genomic level but that they can be divided into two distinct clades that correlate with their disease phenotypes and with a single amino acid substitution in one of the extracellular proteases.

  • Isolation of the Bacteriophage DinoHI from Dichelobacter Nodosus and its Interactions with other Integrated Genetic Elements
    2013
    Co-Authors: Brian F. Cheetham, Garry A. Bloomfield, Dane Parker, Ruth M Kennan, Julian I Rood, Bruce E. Shaw, Megan Sutherl, Jessica A. Hyman, Jenifer Druitt, Margaret E. Katz
    Abstract:

    Abstract: The Gram-negative anaerobic pathogen Dichelobacter Nodosus carries several genetic elements that integrate into the chromosome. These include the intA, intB, intC and intD elements, which integrate adjacent to csrA and pnpA, two putative global regulators of virulence and the virulence-related locus, vrl, which integrates into ssrA. Treatment of D. Nodosus strains with ultraviolet light resulted in the isolation of DinoHI, a member of the Siphoviridae and the first bacteriophage to be identified in D. Nodosus. Part of the DinoHI genome containing the packaging site is found in all D. Nodosus strains tested and is located at the end of the vrl, suggesting a role for DinoHI in the transfer of the vrl by transduction. Like the intB element, the DinoHI genome contains a copy of regA which has similarity to the repressors of lambdoid bacteriophages, suggesting that the maintenance of DinoHI and the intB element may be co-ordinately controlled

  • the aprv5 subtilase is required for the optimal processing of all three extracellular serine proteases from Dichelobacter Nodosus
    PLOS ONE, 2012
    Co-Authors: Ruth M Kennan, Xiaoyan Han, David Steer, Ian A Smith, James C Whisstock
    Abstract:

    Dichelobacter Nodosus is the principal causative agent of ovine footrot and its extracellular proteases are major virulence factors. Virulent isolates of D. Nodosus secrete three subtilisin-like serine proteases: AprV2, AprV5 and BprV. These enzymes are each synthesized as precursor molecules that include a signal (pre-) peptide, a pro-peptide and a C-terminal extension, which are processed to produce the mature active forms. The function of the C-terminal regions of these proteases and the mechanism of protease processing and secretion are unknown. AprV5 contributes to most of the protease activity secreted by D. Nodosus. To understand the role of the C-terminal extension of AprV5, we constructed a series of C-terminal-deletion mutants in D. Nodosus by allelic exchange. The proteases present in the resultant mutants and their complemented derivatives were examined by protease zymogram analysis, western blotting and mass spectrometry. The results showed that the C-terminal region of AprV5 is required for the normal expression of protease activity, deletion of this region led to a delay in the processing of these enzymes. D. Nodosus is an unusual bacterium in that it produces three closely related extracellular serine proteases. We have now shown that one of these enzymes, AprV5, is responsible for its own maturation, and for the optimal cleavage of AprV2 and BprV, to their mature active forms. These studies have increased our understanding of how this important pathogen processes these virulence-associated extracellular proteases and secretes them into its external environment.

  • The AprV5 subtilase is required for the optimal processing of all three extracellular serine proteases from Dichelobacter Nodosus. PLoS One 7:e47932
    2012
    Co-Authors: Xiaoyan Han, Ruth M Kennan, Ian A Smith, James C Whisstock, David L. Steer, Julian I Rood
    Abstract:

    Dichelobacter Nodosus is the principal causative agent of ovine footrot and its extracellular proteases are major virulence factors. Virulent isolates of D. Nodosus secrete three subtilisin-like serine proteases: AprV2, AprV5 and BprV. These enzymes are each synthesized as precursor molecules that include a signal (pre-) peptide, a pro-peptide and a C-terminal extension, which are processed to produce the mature active forms. The function of the C-terminal regions of these proteases and the mechanism of protease processing and secretion are unknown. AprV5 contributes to most of the protease activity secreted by D. Nodosus. To understand the role of the C-terminal extension of AprV5, we constructed a series of C-terminal-deletion mutants in D. Nodosus by allelic exchange. The proteases present in the resultant mutants and their complemented derivatives were examined by protease zymogram analysis, western blotting and mass spectrometry. The results showed that the C-terminal region of AprV5 is required for the normal expression of protease activity, deletion of this region led to a delay in the processing of these enzymes. D. Nodosus is an unusual bacterium in that it produces three closely related extracellular serine proteases. We have now shown that one of these enzymes, AprV5, is responsible for its own maturation, and for the optimal cleavage of AprV2 and BprV, to their mature active forms. These studies have increased our understanding of how this important pathogen processes these virulence-associated extracellular proteases and secrete

Sara Frosth - One of the best experts on this subject based on the ideXlab platform.

  • characterisation of Dichelobacter Nodosus and detection of fusobacterium necrophorum and treponema spp in sheep with different clinical manifestations of footrot
    Veterinary Microbiology, 2015
    Co-Authors: Sara Frosth, Ulrika Konig, Annkristin Nyman, Marit Pringle, Anna Aspan
    Abstract:

    Abstract The aim of this study was to determine the proportion of Dichelobacter Nodosus , Fusobacterium necrophorum and Treponema spp. in sheep with different clinical manifestations of footrot compared to healthy sheep both at flock and individual level. The second aim was to characterise D. Nodosus with respect to virulence, presence of intA gene and the serogroups. Swab samples ( n  = 1000) from footrot-affected ( n  = 10) and healthy flocks ( n  = 10) were analysed for the presence of D. Nodosus , F. necrophorum and Treponema spp. by real-time PCR and culturing ( D. Nodosus only). Dichelobacter Nodosus isolates ( n  = 78) and positive swabs ( n  = 474) were analysed by real-time PCR for the aprV2/B2 and the intA genes and by PCR for the fimA gene (isolates only). D. Nodosus was more commonly found in flocks affected with footrot than in clinically healthy flocks. A significant association was found between feet with severe footrot lesions and the aprV2 gene and between feet with moderate or no lesions and the aprB2 gene, respectively. F. necrophorum was more commonly found in flocks with footrot lesions than in flocks without lesions. No significant association was found between sheep flocks affected with footrot and findings of Treponema spp. or the intA gene. Benign D. Nodosus of six different serogroups was detected in twelve flocks and virulent D. Nodosus of serogroup G in one. In conclusion, D. Nodosus and F. necrophorum were more commonly found in feet with footrot than in healthy feet. The majority of D. Nodosus detected was benign, while virulent D. Nodosus was only detected in a single flock.

  • genomic evidence for a globally distributed bimodal population in the ovine footrot pathogen Dichelobacter Nodosus
    Mbio, 2014
    Co-Authors: Ruth M Kennan, Om P Dhungyel, Richard Whittington, Sara Frosth, Torsten Seemann, Marianne Gilhuus
    Abstract:

    ABSTRACT Footrot is a contagious, debilitating disease of sheep, causing major economic losses in most sheep-producing countries. The causative agent is the Gram-negative anaerobe Dichelobacter Nodosus. Depending on the virulence of the infective bacterial strain, clinical signs vary from a mild interdigital dermatitis (benign footrot) to severe underrunning of the horn of the hoof (virulent footrot). The aim of this study was to investigate the genetic relationship between D. Nodosus strains of different phenotypic virulences and between isolates from different geographic regions. Genome sequencing was performed on 103 D. Nodosus isolates from eight different countries. Comparison of these genome sequences revealed that they were highly conserved, with >95% sequence identity. However, single nucleotide polymorphism analysis of the 31,627 nucleotides that were found to differ in one or more of the 103 sequenced isolates divided them into two distinct clades. Remarkably, this division correlated with known virulent and benign phenotypes, as well as with the single amino acid difference between the AprV2 and AprB2 proteases, which are produced by virulent and benign strains, respectively. This division was irrespective of the geographic origin of the isolates. However, within one of these clades, isolates from different geographic regions generally belonged to separate clusters. In summary, we have shown that D. Nodosus has a bimodal population structure that is globally conserved and provide evidence that virulent and benign isolates represent two distinct forms of D. Nodosus strains. These data have the potential to improve the diagnosis and targeted control of this economically significant disease. IMPORTANCE The Gram-negative anaerobic bacterium Dichelobacter Nodosus is the causative agent of ovine footrot, a disease of major importance to the worldwide sheep industry. The known D. Nodosus virulence factors are its type IV fimbriae and extracellular serine proteases. D. Nodosus strains are designated virulent or benign based on the type of disease caused under optimal climatic conditions. These isolates have similar fimbriae but distinct extracellular proteases. To determine the relationship between virulent and benign isolates and the relationship of isolates from different geographical regions, a genomic study that involved the sequencing and subsequent analysis of 103 D. Nodosus isolates was undertaken. The results showed that D. Nodosus isolates are highly conserved at the genomic level but that they can be divided into two distinct clades that correlate with their disease phenotypes and with a single amino acid substitution in one of the extracellular proteases.

  • Development and comparison of a real-time PCR assay for detection of Dichelobacter Nodosus with culturing and conventional PCR: harmonisation between three laboratories
    Acta Veterinaria Scandinavica, 2012
    Co-Authors: Sara Frosth, Øystein Angen, Jannice S Slettemeås, Hannah J Jørgensen, Anna Aspan
    Abstract:

    Background Ovine footrot is a contagious disease with worldwide occurrence in sheep. The main causative agent is the fastidious bacterium Dichelobacter Nodosus . In Scandinavia, footrot was first diagnosed in Sweden in 2004 and later also in Norway and Denmark. Clinical examination of sheep feet is fundamental to diagnosis of footrot, but D. nodosu s should also be detected to confirm the diagnosis. PCR-based detection using conventional PCR has been used at our institutes, but the method was laborious and there was a need for a faster, easier-to-interpret method. The aim of this study was to develop a TaqMan-based real-time PCR assay for detection of D. Nodosus and to compare its performance with culturing and conventional PCR. Methods A D. Nodosus- specific TaqMan based real-time PCR assay targeting the 16S rRNA gene was designed. The inclusivity and exclusivity (specificity) of the assay was tested using 55 bacterial and two fungal strains. To evaluate the sensitivity and harmonisation of results between different laboratories, aliquots of a single DNA preparation were analysed at three Scandinavian laboratories. The developed real-time PCR assay was compared to culturing by analysing 126 samples, and to a conventional PCR method by analysing 224 samples. A selection of PCR-products was cloned and sequenced in order to verify that they had been identified correctly. Results The developed assay had a detection limit of 3.9 fg of D. Nodosus genomic DNA. This result was obtained at all three laboratories and corresponds to approximately three copies of the D. Nodosus genome per reaction. The assay showed 100% inclusivity and 100% exclusivity for the strains tested. The real-time PCR assay found 54.8% more positive samples than by culturing and 8% more than conventional PCR. Conclusions The developed real-time PCR assay has good specificity and sensitivity for detection of D. Nodosus , and the results are easy to interpret. The method is less time-consuming than either culturing or conventional PCR.

Richard Whittington - One of the best experts on this subject based on the ideXlab platform.

  • genomic evidence for a globally distributed bimodal population in the ovine footrot pathogen Dichelobacter Nodosus
    Mbio, 2014
    Co-Authors: Ruth M Kennan, Om P Dhungyel, Richard Whittington, Sara Frosth, Torsten Seemann, Marianne Gilhuus
    Abstract:

    ABSTRACT Footrot is a contagious, debilitating disease of sheep, causing major economic losses in most sheep-producing countries. The causative agent is the Gram-negative anaerobe Dichelobacter Nodosus. Depending on the virulence of the infective bacterial strain, clinical signs vary from a mild interdigital dermatitis (benign footrot) to severe underrunning of the horn of the hoof (virulent footrot). The aim of this study was to investigate the genetic relationship between D. Nodosus strains of different phenotypic virulences and between isolates from different geographic regions. Genome sequencing was performed on 103 D. Nodosus isolates from eight different countries. Comparison of these genome sequences revealed that they were highly conserved, with >95% sequence identity. However, single nucleotide polymorphism analysis of the 31,627 nucleotides that were found to differ in one or more of the 103 sequenced isolates divided them into two distinct clades. Remarkably, this division correlated with known virulent and benign phenotypes, as well as with the single amino acid difference between the AprV2 and AprB2 proteases, which are produced by virulent and benign strains, respectively. This division was irrespective of the geographic origin of the isolates. However, within one of these clades, isolates from different geographic regions generally belonged to separate clusters. In summary, we have shown that D. Nodosus has a bimodal population structure that is globally conserved and provide evidence that virulent and benign isolates represent two distinct forms of D. Nodosus strains. These data have the potential to improve the diagnosis and targeted control of this economically significant disease. IMPORTANCE The Gram-negative anaerobic bacterium Dichelobacter Nodosus is the causative agent of ovine footrot, a disease of major importance to the worldwide sheep industry. The known D. Nodosus virulence factors are its type IV fimbriae and extracellular serine proteases. D. Nodosus strains are designated virulent or benign based on the type of disease caused under optimal climatic conditions. These isolates have similar fimbriae but distinct extracellular proteases. To determine the relationship between virulent and benign isolates and the relationship of isolates from different geographical regions, a genomic study that involved the sequencing and subsequent analysis of 103 D. Nodosus isolates was undertaken. The results showed that D. Nodosus isolates are highly conserved at the genomic level but that they can be divided into two distinct clades that correlate with their disease phenotypes and with a single amino acid substitution in one of the extracellular proteases.

  • modulation of inter vaccination interval to avoid antigenic competition in multivalent footrot Dichelobacter Nodosus vaccines in sheep
    Vaccine, 2009
    Co-Authors: Om P Dhungyel, Richard Whittington
    Abstract:

    Virulent footrot is a significant disease of sheep in most sheep farming countries; a strain/serogroup of the anaerobic bacterium Dichelobacter Nodosus is the essential transmitting agent. Commercial multivalent footrot vaccines containing nine fimbrial serogroups (A through I) of D. Nodosus produce relatively low and short term antibody responses due to antigenic competition, in contrast to higher and longer responses provided by monovalent or bivalent vaccines. The latter were important components of successful eradication programs for endemic footrot caused by either one or two serogroups of D. Nodosus in Nepal, Bhutan, and several flocks in Australia. However, the presence of up to six serogroups in some Australian flocks and the use of an annual bivalent vaccination regime to progressively eradicate serogroups would require a long term program. In this study we report the results of a sequential vaccination trial testing different time intervals between different bivalent vaccinations. Intervals of 12, 9, 6, 3 and 0 months were tested. The 1st vaccination was with recombinant fimbrial antigens for serogroups A and B while the 2nd vaccination was with D and E. There were no significant differences between the antibody responses for time intervals of 3, 6, 9 and 12 months whereas there was a reduced response when sheep were vaccinated with two bivalent vaccines (four antigens) concurrently, indicating antigenic competition. Therefore an inter-vaccination interval of 3 months can be applied between two different bivalent vaccines without detrimental impact on the humoral immune responses to the various fimbrial antigens of D. Nodosus. These results could have wider applications in vaccination against diseases caused by multivalent or multistrain microbes.

  • twitching motility is essential for virulence in Dichelobacter Nodosus
    Journal of Bacteriology, 2008
    Co-Authors: Xiaoyan Han, Ruth M Kennan, John K Davies, L A Reddacliff, Om P Dhungyel, Richard Whittington, Lynne Turnbull
    Abstract:

    Type IV fimbriae are essential virulence factors of Dichelobacter Nodosus, the principal causative agent of ovine foot rot. The fimA fimbrial subunit gene is required for virulence, but fimA mutants exhibit several phenotypic changes and it is not certain if the effects on virulence result from the loss of type IV fimbria-mediated twitching motility, cell adherence, or reduced protease secretion. We showed that mutation of either the pilT or pilU gene eliminated the ability to carry out twitching motility. However, the pilT mutants displayed decreased adhesion to epithelial cells and reduced protease secretion, whereas the pilU mutants had wild-type levels of extracellular protease secretion and adherence. These data provided evidence that PilT is required for the type IV fimbria-dependent protease secretion pathway in D. Nodosus. It was postulated that sufficient fimbrial retraction must occur in the pilU mutants to allow protease secretion, but not twitching motility, to take place. Although no cell movement was detected in a pilU mutant of D. Nodosus, aberrant motion was detected in an equivalent mutant of Pseudomonas aeruginosa. These observations explain how in D. Nodosus protease secretion can occur in a pilU mutant but not in a pilT mutant. In addition, virulence studies with sheep showed that both the pilT and pilU mutants were avirulent, providing evidence that mutation of the type IV fimbrial system affects virulence by eliminating twitching motility, not by altering cell adherence or protease secretion.

Rosemary Grogonothomas - One of the best experts on this subject based on the ideXlab platform.

  • multiple locus vntr analysis highlights that geographical clustering and distribution of Dichelobacter Nodosus the causal agent of footrot in sheep correlates with inter country movements
    Infection Genetics and Evolution, 2014
    Co-Authors: Claire L Russell, L E Green, Leo A Calvobado, G F Medley, Elizabeth M H Wellington, L J Moore, Edward M Smith, Rosemary Grogonothomas
    Abstract:

    Dichelobacter Nodosus is a Gram-negative, anaerobic bacterium and the causal agent of footrot in sheep. Multiple locus variable number tandem repeat (VNTR) analysis (MLVA) is a portable technique that involves the identification and enumeration of polymorphic tandem repeats across the genome. The aims of this study were to develop an MLVA scheme for D. Nodosus suitable for use as a molecular typing tool, and to apply it to a global collection of isolates. Seventy-seven isolates selected from regions with a long history of footrot (GB, Australia) and regions where footrot has recently been reported (India, Scandinavia), were characterised. From an initial 61 potential VNTR regions, four loci were identified as usable and in combination had the attributes required of a typing method for use in bacterial epidemiology: high discriminatory power (D > 0.95), typeability and reproducibility. Results from the analysis indicate that D. Nodosus appears to have evolved via recombinational exchanges and clonal diversification. This has resulted in some clonal complexes that contain isolates from multiple countries and continents; and others that contain isolates from a single geographic location (country or region). The distribution of alleles between countries matches historical accounts of sheep movements, suggesting that the MLVA technique is sufficiently specific and sensitive for an epidemiological investigation of the global distribution of D. Nodosus.

  • the occurrence of treponemes in contagious ovine digital dermatitis and the characterisation of associated Dichelobacter Nodosus
    Veterinary Microbiology, 2005
    Co-Authors: L J Moore, Martin J Woodward, Rosemary Grogonothomas
    Abstract:

    Contagious ovine digital dermatitis (CODD) is a recently recorded, apparently new infection of the ovine hoof, which differs clinically from footrot caused by Dichelobacter Nodosus and which fails to respond well to accepted treatment practices for footrot. Despite the welfare implications of such an infection, very little research has been performed on CODD to date and the aetiology remains confused. Suggestions have been made that there is a potential role for treponemes in the pathogenesis of CODD but that D. Nodosus is apparently not involved. Six farms were therefore targeted in this study to provide a more in-depth investigation into the bacterial flora of CODD lesions. Dark ground microscopy, culture and PCR techniques were used, concentrating on the presence of D. Nodosus and spirochaetes, particularly those of the genus Treponema. The results demonstrated that isolates of D. Nodosus were indeed present in a high percentage (74%) of CODD lesions compared with 31% of apparently healthy feet. The isolates were shown to be of similar virulence type to those reported previously in cases of footrot, and the range of serogroups was also found to be similar to footrot, with serogroup H being prevalent. Treponemes were present in 70% of CODD lesions and 38% of apparently healthy feet, supporting a possible association between CODD and treponemes. However, any further progress on the aetiology of CODD and the potential for novel, effective treatment will depend on an improved ability to culture these organisms routinely in the laboratory thereby enabling their complete characterisation.

  • the detection and characterisation of Dichelobacter Nodosus from cases of ovine footrot in england and wales
    Veterinary Microbiology, 2005
    Co-Authors: L J Moore, Laura E. Green, G J Wassink, Rosemary Grogonothomas
    Abstract:

    Footrot, caused by the strictly anaerobic bacterium Dichelobacter Nodosus, is the most common cause of lameness in sheep in Great Britain but problems exist in association with its diagnosis and control. The fastidious nature of D. Nodosus means that complex media and several weeks are required for characterisation. An alternative method to simplify and enhance the detection of D. Nodosus in clinical samples is therefore highly desirable. In terms of control, anecdotal evidence from the farming community suggests that the commercially available vaccine, based on Australian isolates of D. Nodosus, is not widely employed in this country due to its perceived inefficacy. Seven hundred and six isolates, collected from outbreaks in England and Wales, were therefore used to investigate these issues. A 16S rRNA PCR was adapted to detect D. Nodosus in clinical material within 1 day of sampling; a 15% increase in detection compared with culture and less than 1% false negatives were achieved. This represents a major advance in the rapid diagnosis of footrot and will be of great value to practitioners and diagnostic laboratories. Bacterial virulence was tested using protease thermostability and zymogram assays, whilst serogrouping was performed by slide agglutination. All isolates demonstrated virulence patterns previously recorded in Australia and all nine serogroups of D. Nodosus (A-I) were represented. Serogroup H was predominant. There was, therefore, no evidence for the presence of novel strains of D. Nodosus compared with Australia suggesting the need for further investigation into farmers' views on the use of the commercial vaccine in Great Britain.

Tötemeyer S. - One of the best experts on this subject based on the ideXlab platform.

  • Genomic heterogeneity of Dichelobacter Nodosus within and between UK sheep flocks and between age groups within a flock
    'Springer Science and Business Media LLC', 2020
    Co-Authors: Davies P. L., Blanchard A. M., Staley C. E., Bollard N. J., Coffey T. J., Tötemeyer S.
    Abstract:

    BackgroundFootrot and interdigital dermatitis are endemic infectious diseases in all sheep farming regions, impairing welfare and production. The development of efficacious vaccines against the primary causative pathogen has been hampered by the extensive antigenic diversity of Dichelobacter Nodosus. Understanding the heterogeneity of the pathogen within and between flocks is essential if the feasibility of bespoke vaccine production is to be assessed for use in the U.K.ResultsIn this study 56 ewe and lamb isolates from 9 flocks were compared by D. Nodosus serogroup and Multi Locus Sequence Type which provides significantly enhanced discriminatory power for molecular epidemiology. Serogroup heterogeneity between flocks ranged from two to five unique serogroups per flock. Three flocks contained isolates of two serogroups, two flocks contained isolates of three serogroups and one flock included isolates of five serogroups. Analysis of 25 isolates from one flock with high prevalence of lameness, identified that serogroup and sequence type was significantly correlated with age. Significantly higher proportion of lambs were infected with serogroup B (principally ST85) as opposed to serogroup H (principally ST86), which predominated amongst adult sheep.ConclusionsGenomic heterogeneity of the pathogen was significantly lower within flock compared to heterogenicity observed between flocks. Furthermore, this study indicates that within a flock, the host-pathogen dynamics and susceptibility to particular D. Nodosus strains may be age dependent

  • Novel inflammatory cell infiltration scoring system to investigate healthy and footrot affected ovine interdigital skin
    'PeerJ', 2018
    Co-Authors: Agbaje M, Maboni G, Blanchard A, Stewart C, Cs Rutland, Bexon M, Tötemeyer S.
    Abstract:

    Ovine footrot is a degenerative disease of sheep feet leading to the separation of hoof-horn from the underlying skin and lameness. This study quantitatively examined histological features of the ovine interdigital skin as well as their relationship with pro-inflammatory cytokine (IL-1β) and virulent Dichelobacter Nodosus in footrot. From 55 healthy and 30 footrot ovine feet, parallel biopsies (one fixed for histology) were collected post-slaughter and analysed for lesions and histopathological analysis using haematoxylin and eosin and Periodic Acid-Schiff. Histological lesions were similar in both conditions while inflammatory scores mirror IL-1β expression levels. Increased inflammatory score corresponded with high virulent D. Nodosus load and was significant (p < 0.0001) in footrot feet with an inflammatory score of 3 compared to scores 1 and 2. In addition, in contrast to healthy tissues, localisation of eubacterial load extended beyond follicular depths in footrot samples. The novel inflammatory cell infiltration scoring system in this study may be used to grade inflammatory response in the ovine feet and demonstrated an association between severity of inflammatory response and increased virulent D. Nodosus load

  • A distinct bacterial dysbiosis associated skin inflammation in ovine footrot
    'Springer Science and Business Media LLC', 2017
    Co-Authors: Maboni G, Frosth S, Blanchard A, Stewart C, Emes R, Tötemeyer S.
    Abstract:

    Ovine footrot is a highly prevalent bacterial disease caused by Dichelobacter Nodosus and characterised by the separation of the hoof horn from the underlying skin. The role of innate immune molecules and other bacterial communities in the development of footrot lesions remains unclear. This study shows a significant association between the high expression of IL1β and high D. Nodosus load in footrot samples. Investigation of the microbial population identified distinct bacterial populations in the different disease stages and also depending on the level of inflammation. Treponema (34%), Mycoplasma (29%) and Porphyromonas (15%) were the most abundant genera associated with high levels of inflammation in footrot. In contrast, Acinetobacter (25%), Corynebacteria (17%) and Flavobacterium (17%) were the most abundant genera associated with high levels of inflammation in healthy feet. This demonstrates for the first time there is a distinct microbial community associated with footrot and high cytokine expression