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

  • Novel seM‐types of Streptococcus equi subsp. equi identified in isolates circulating in Argentina
    Equine veterinary journal, 2021
    Co-Authors: C.p. Bustos, Andrew S. Waller, A.j. Muñoz, Nora Guida, María Mesplet
    Abstract:

    BACKGROUND Strangles is a worldwide infectious disease caused by Streptococcus equi subsp. equi that affects the upper respiratory tract of horses. Streptococcus equi subsp. equi characterisation by seM-typing is internationally used for epidemiological studies and comparison of isolates. OBJECTIVES To identify and to compare the seM-types of Argentinian isolates of Streptococcus equi subsp. equi. STUDY DESIGN Investigation of bacterial isolates using molecular and phylogenetic approaches. METHODS A total of 59 Argentinian isolates of Streptococcus equi subsp. equi obtained between 2007 and 2019 were studied by seM-typing. The sequence similarity of Argentinian seM-types and the other alleles available on the seM database was determined using BLAST and phylogenetic analysis was performed using the Neighbour-Joining algorithm. The amino acid sequences were predicted and compared with the predicted amino acid sequence of the reference strain 4047 using the MEGA 7 software and PROVEAN tool. RESULTS Eight seM-types were found among the isolates. Only one of them (seM-61) has been previously reported and the other seven alleles (seM-129, seM-130, seM-131, seM-132, seM-133, seM-134 and seM-135) were novel seM sequences. High genetic similarity was observed among the Argentinian seM-types, with the exception of seM-130. No functional effects of amino acid differences were predicted. MAIN LIMITATIONS The number of related and unrelated isolates per year. CONCLUSIONS Seven novel seM-types and seM-61 that were previously reported in Brazil were circulating in Argentina which were identified as circulating in Argentinian horses between 2007 and 2019. The high genetic similarity among the Argentinian and Brazilian seM-types suggests that there is a geographical distribution of strain types. The geographical restriction of strains is likely to reflect the movement of horses between different equine disciplines and neighbouring countries.

  • Streptococcus equi: breaking its strangles-hold.
    The Veterinary record, 2018
    Co-Authors: Andrew S. Waller
    Abstract:

    Andrew Waller, head of bacteriology at the AHT, describes Streptococcus equi, the causative agent of strangles in horses, and discusses progress with the latest research aimed at improving vaccines against this global disease.

  • Localised mitogenic activity in horses following infection with Streptococcus equi
    Research in veterinary science, 2015
    Co-Authors: Rebecca K. Mclean, Andrew S. Waller, N. Rash, Carl Robinson, Romain Paillot
    Abstract:

    Streptococcus equi subspecies equi (S. equi) is the causative agent of strangles, a highly contagious upper respiratory disease of equids. Streptococcus equi produces superantigens (sAgs), which are thought to contribute to strangles pathogenicity through non-specific T-cell activation and pro-inflammatory response. Streptococcus equi infection induces abscesses in the lymph nodes of the head and neck. In some individuals, some abscess material remains into the guttural pouch and inspissates over time to form chondroids which can harbour live S. equi. The aim of this study was to determine the sites of sAg production during infection and therefore improve our understanding of their role. Abscess material, chondroids and serum collected from equidae with signs of strangles were tested in mitogenic assays. Mitogenic sAg activity was only detected in abscess material and chondroids. Our data support the localised in vivo activity of sAg during both acute and carrier phases of S. equi infection.

  • Detection of Streptococcus equi subspecies equi using a triplex qPCR assay.
    Veterinary journal (London England : 1997), 2012
    Co-Authors: K. Webb, Carl Robinson, Karen F. Steward, Colin Barker, Tihana Harrison, Zoe Heather, J. Richard Newton, Andrew S. Waller
    Abstract:

    Genome sequencing data for Streptococcus equi subspecies equi and zooepidemicus were used to develop a novel diagnostic triplex quantitative PCR (qPCR) assay targeting two genes specific to S. equi (eqbE and SEQ2190) and a unique 100 base pair control DNA sequence (SZIC) inserted into the SZO07770 pseudogene of S. zooepidemicus strain H70. This triplex strangles qPCR assay can provide results within 2 h of sample receipt, has an overall sensitivity of 93.9% and specificity of 96.6% relative to the eqbE singlex assay and detects S. equi at levels below the threshold of the culture assay, even in the presence of contaminating bacteria.

  • Genetic diversity of Streptococcus equi subsp. zooepidemicus and doxycycline resistance in kennelled dogs
    Journal of clinical microbiology, 2012
    Co-Authors: Victoria J. Chalker, Andrew S. Waller, K. Webb, Emma Spearing, P. Crosse, Joe Brownlie, Kerstin Erles
    Abstract:

    The genetic diversity and antibiotic resistance profiles of 38 Streptococcus equi subsp. zooepidemicus isolates were determined from a kennelled canine population during two outbreaks of hemorrhagic pneumonia (1999 to 2002 and 2007 to 2010). Analysis of the szp gene hypervariable region and the 16S-23S rRNA intergenic spacer region and multilocus sequence typing (MLST) indicated a predominant tetO-positive, doxycycline-resistant ST-10 strain during 1999 to 2002 and a predominant tetM-positive doxycycline-resistant ST-62 strain during 2007 to 2010.

Brad Lage - One of the best experts on this subject based on the ideXlab platform.

Silvia M. Montano - One of the best experts on this subject based on the ideXlab platform.

Marcus J. Zervos - One of the best experts on this subject based on the ideXlab platform.

  • Streptococcus equi subsp. zooepidemicus meningitis
    Journal of Medical Microbiology, 2008
    Co-Authors: M. Jovanovic, G. Stevanovic, T. Tosic, B. Stošović, Marcus J. Zervos
    Abstract:

    A 72-year-old woman was hospitalized for Streptococcus equi subsp. zooepidemicus meningitis. The same organism was cultured from her two horses. She denied contact with horses, but had a practice of consuming unpasteurized milk from a cow. The cow was in the same stable as the horses, and the ill woman's son milked the cow.

Iain C. Sutcliffe - One of the best experts on this subject based on the ideXlab platform.

  • The molecular basis of Streptococcus equi infection and disease.
    Microbes and infection, 2002
    Co-Authors: Dean J. Harrington, Iain C. Sutcliffe, N. Chanter
    Abstract:

    Streptococcus equi is the aetiological agent of strangles, one of the most prevalent diseases of the horse. The animal suffering and economic burden associated with this disease necessitate effective treatment. Current antibiotic therapy is often ineffective and thus recent attention has focused on vaccine development. A systematic understanding of S. equi virulence, leading to the identification of targets to which protective immunity can be directed, is a prerequisite of the development of such a vaccine. Here, the virulence factors of S. equi are reviewed.

  • Surface immunolocalisation of HPr in the equine pathogen Streptococcus equi.
    Systematic and applied microbiology, 2001
    Co-Authors: Sarah Dixon, Dean J. Harrington, Malcolm Haswell, Iain C. Sutcliffe
    Abstract:

    Summary We have investigated the surface localisation of the phosphotransferase system protein HPr in the equine pathogen Streptococcus equi subsp. equi using immunogold localisation and transmission electron microscopy. Like the LppC acid phosphatase lipoprotein, a reference surface antigen, the S. equi HPR could be clearly detected on the surfaces of intact cells. This study is consistent with previous reports that some streptococcal HPr is cell surface associated and suggests that the extracytoplasmic mobilisation and transfer of phosphate groups by streptococci warrant further investigation.

  • Characterization of acid phosphatase activities in the equine pathogen Streptococcus equi.
    Systematic and applied microbiology, 2000
    Co-Authors: Andrea Hamilton, Dean Harrington, Iain C. Sutcliffe
    Abstract:

    Acid phosphatases hydrolyse phosphomonoesters at acidic pH in a variety of physiological contexts. The recently defined class C family of acid phosphatases includes the 32 kDa LppC lipoprotein of Streptococcus equisimilis. To define further the distribution of acid phosphatases in the genus Streptococcus we have examined the equine pathogens Streptococcus equi subsp. equi and Streptococcus equi subsp. zooepidemicus. Whole cell assays indicated that these organisms possess two acid phosphatases with activity optima at pH 5.0 and pH 6.0-6.5 and that only the former of these was, like LppC, resistant to EDTA. Western blotting with a polyclonal anti-LppC antiserum revealed the presence of a cross-reactive 32 kDa protein in both organisms. The cross-reactive protein in S. equi was shown to be a surface accessible lipoprotein as its processing was inhibited by the antibiotic globomycin and it was released from whole cells by treatment with trypsin. The presence of DNA sequences homologous to the S. equisimilis lppC gene were confirmed by PCR. These data strongly suggest that Streptococcus equi subsp. equi and Streptococcus equi subsp. zooepidemicus produce a lipoprotein acid phosphatase homologous to LppC of S. equisimilis.

  • Identification of Methionine-processed HPr in the equine Pathogen Streptococcus equi
    Systematic and applied microbiology, 2000
    Co-Authors: Iain C. Sutcliffe, Joanne Trigg, Dean Harrington
    Abstract:

    Using preparative electrophoresis, a low molecular weight protein has been partially purified from a cell extract of the equine pathogen Streptococcus equi susp. equi. N-terminal sequence analysis and Western blotting revealed the protein to be HPr, a central component of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). Interestingly, the only form of the HPr protein detected in S. equi was one with the amino-terminal methionine removed, a modification that has previously been associated with surface localization of streptococcal HPr proteins.