Project description:Streptococcus equi subsp. equi (SEE) is a host-restricted bacterium that causes the common infectious upper respiratory disease known as strangles in horses. Perpetuation of SEE infection appears attributable to inapparent carrier horses because it does not persist long-term in the environment, infect other host mammals or vectors, and result in short-lived immunity. Whether pathogen factors enable SEE to remain in horses without causing clinical signs remains poorly understood. Thus, our objective was to use next-generation sequencing technologies to characterize the transcriptome of isolates of SEE from horses with acute clinical strangles and inapparent carrier horses to assess pathogen-associated changes that might reflect adaptions of SEE to the host contributing to inapparent carriage. RNA sequencing of SEE isolates from Pennsylvania demonstrated no genes that were differentially expressed between acute clinical and inapparent carrier isolates of SEE.
Project description:By screening a genomic lambda library of Streptococcus equi subsp. zooepidemicus, we have cloned and sequenced a gene, termed fnz, encoding a fibronectin (Fn)-binding protein called FNZ. On the basis of the deduced amino acid sequence of FNZ, the mature protein has a molecular mass of approximately 61 kDa. Analysis of FNZ reveals a structural organization similar to that of other cell surface proteins from streptococci and staphylococci. The Fn-binding activity is localized to two domains in the C-terminal part of FNZ. One domain is composed of five repeats, which contain a motif similar to what has earlier been found in other Fn-binding proteins in streptococci and staphylococci. The first and second repeats are separated by a short stretch of amino acids, including the motif LAGESGET, which is an important part of the second Fn-binding domain. This motif is also present in an Fn-binding domain (UR) in protein F of Streptococcus pyogenes. A fusion protein covering the Fn-binding domain of FNZ inhibits the binding of the 29-kDa N-terminal fragment of Fn to cells of various streptococcal species as well as to Staphylococcus aureus.
Project description:Streptococcus equi subsp. zooepidemicus is a known zoonotic pathogen. In this public health investigation conducted in Virginia, USA, in 2013, we identified a probable family cluster of S. zooepidemicus cases linked epidemiologically and genetically to infected guinea pigs. S. zooepidemicus infections should be considered in patients who have severe clinical illness and report guinea pig exposure.
Project description:We describe a case of an infant with recurrent bacteremia caused by Streptococcus equi subsp. zooepidemicus, likely transmitted from mother to infant. Our case highlights the importance of an epidemiological history and molecular diagnostics in ascertaining insights into transmission, pathogenesis, and optimal management.
Project description:BackgroundStreptococcus equi subspecies equi (S equi) is the cause of Strangles, one of the most prevalent diseases of horses worldwide. Variation within the immunodominant SeM protein has been documented, but a new eight-component fusion protein vaccine, Strangvac, does not contain live S equi or SeM and conservation of the antigens it contains have not been reported.ObjectiveTo define the diversity of the eight Strangvac antigens across a diverse S equi population.Study designGenomic description.MethodsAntigen sequences from the genomes of 759 S equi isolates from 19 countries, recovered between 1955 and 2018, were analysed. Predicted amino acid sequences in the antigen fragments of SEQ0256(Eq5), SEQ0402(Eq8), SEQ0721(EAG), SEQ0855(SclF), SEQ0935(CNE), SEQ0999(IdeE), SEQ1817(SclI) and SEQ2101(SclC) in Strangvac and SeM were extracted from the 759 assembled genomes and compared.ResultsThe predicted amino acid sequences of SclC, SclI and IdeE were identical across all 759 genomes. CNE was truncated in the genome of five (0.7%) isolates. SclF was absent from one genome and another encoded a single amino acid substitution. EAG was truncated in two genomes. Eq5 was truncated in four genomes and 123 genomes encoded a single amino acid substitution. Eq8 was truncated in three genomes, one genome encoded four amino acid substitutions and 398 genomes encoded a single amino acid substitution at the final amino acid of the Eq8 antigen fragment. Therefore, at least 1579 (99.9%) of 1580 amino acids in Strangvac were identical in 743 (97.9%) genomes, and all genomes encoded identical amino acid sequences for at least six of the eight Strangvac antigens.Main limitationsThree hundred and seven (40.4%) isolates in this study were recovered from horses in the UK.ConclusionsThe predicted amino acid sequences of antigens in Strangvac were highly conserved across this collection of S equi.
Project description:In 2019, Streptococcus equi subsp. zooepidemicus was recognized as an emerging pathogen of swine, associated with sudden deaths, increased abortion rates and septicaemia. Limited data are available regarding this disease in pigs. The objectives of this study were to clarify clinical progression, pathogen shedding, transmission, gross and microscopic lesions following infection in pigs. Six weeks old pigs were inoculated with either S. zooepidemicus sequence type 194 (inoculated, n = 6) or sham inoculated with sterile culture broth (sentinels, n = 4). Animals were housed in the same room, in two pens 2 m apart. Pigs were monitored twice daily for clinical signs, and rectal, nasal and oral swabs were collected once daily. A full necropsy was performed if welfare was a concern or at 5 days post-inoculation (dpi). All sentinels remained disease free and their samples tested negative for the pathogen of interest. All inoculated pigs developed fever within 8 h of inoculation, and severe disease was observed after 2 dpi. A total of 4/6 inoculated pigs developed clinical signs that compromised animal welfare and were euthanized. Nasal swabs (15/23), followed by rectal swabs (9/23) yield the highest number of positive ante-mortem samples. Clinically healthy, inoculated pigs had detectable levels of S. zooepidemicus in rectal and nasal swabs. Reactive submandibular lymph nodes, kidney petechiae and splenomegaly were found in six of six inoculated pigs. These data suggest that subclinically infected pigs may spread the pathogen through nasal secretions and faeces. Direct contact seems to be required for transmission.
Project description:Cefquinome is administered in horses for the treatment of respiratory infection caused by Streptococcus equi subsp. zooepidemicus, and septicemia caused by Escherichia coli. However, there have been no attempts to use cefquinome against Streptococcus equi subsp. equi (S. equi), the causative agent of strangles. Hence the objective of this study was to calculate an optimal dosage of cefquinome against S. equi based on pharmacokinetics and pharmacodynamics integration. Cefquinome (1.0 mg/kg) was administered by intravenous and intramuscular routes to six healthy thoroughbred foals. Serum cefquinome concentrations were determined by high-performance liquid chromatography. The in vitro and ex vivo antibacterial activity were determined from minimum inhibitory concentrations (MIC) and bacterial killing curves. The optimal dosage was calculated from the integration of pharmacokinetic parameters and area under the curve (AUC24h/MIC) values. Total body clearance and volume of distribution of cefquinome after intravenous administration were 0.06 L/h/kg and 0.09 L/kg, respectively. Following intramuscular administration, a maximum concentration of 0.73 ?g/mL at 1.52 h (Tmax) and a systemic bioavailability of 37.45% were observed. The MIC of cefquinome against S. equi was 0.016 ?g/mL. The ex vivo AUC24h/MIC values representing bacteriostatic, and bactericidal activity were 113.11, and 143.14 h, respectively. Whereas the %T?>?MIC for bactericidal activity was 153.34%. In conclusion, based on AUC24h/MIC values and pharmacokinetic parameters, cefquinome when administered by intramuscularly at a dosage of 0.53 mg/kg every 24 h, would be effective against infection caused by S. equi in foals. Further studies may be necessary to confirm its therapeutic efficacy in a clinical environment.
Project description:Streptococcus equi subsp. equi (SEE) is a host-restricted equine pathogen considered to have evolved from Streptococcus equi subsp. zooepidemicus (SEZ). SEZ is promiscuous in host range and is commonly recovered from horses as a commensal. Comparison of a single strain each of SEE and SEZ using whole-genome sequencing, supplemented by PCR of selected genes in additional SEE and SEZ strains, was used to characterize the evolution of SEE. But the known genetic variability of SEZ warrants comparison of the whole genomes of multiple SEE and SEZ strains. To fill this knowledge gap, we utilized whole-genome sequencing to characterize the accessory genome elements (AGEs; i.e., elements present in some SEE strains but absent in SEZ or vice versa) and methylomes of 50 SEE and 50 SEZ isolates from Texas. Consistent with previous findings, AGEs consistently found in all SEE isolates were primarily from mobile genetic elements that might contribute to host restriction or pathogenesis of SEE. Fewer AGEs were identified in SEZ because of the greater genomic variability among these isolates. The global methylation patterns of SEE isolates were more consistent than those of the SEZ isolates. Among homologous genes of SEE and SEZ, differential methylation was identified only in genes of SEE encoding proteins with functions of quorum sensing, exopeptidase activity, and transitional metal ion binding. Our results indicate that effects of genetic mobile elements in SEE and differential methylation of genes shared by SEE and SEZ might contribute to the host specificity of SEE. IMPORTANCE Strangles, caused by the host-specific bacterium Streptococcus equi subsp. equi (SEE), is the most commonly diagnosed infectious disease of horses worldwide. Its ancestor, Streptococcus equi subsp. zooepidemicus (SEZ), is frequently isolated from a wide array of hosts, including horses and humans. A comparison of the genomes of a single strain of SEE and SEZ has been reported, but sequencing of further isolates has revealed variability among SEZ strains. Thus, the importance of this study is that it characterizes genomic and methylomic differences of multiple SEE and SEZ isolates from a common geographic region (viz., Texas). Our results affirm many of the previously described differences between the genomes of SEE and SEZ, including the role of mobile genetic elements in contributing to host restriction. We also provide the first characterization of the global methylome of Streptococcus equi and evidence that differential methylation might contribute to the host restriction of SEE.
Project description:Streptococcus equi subsp. zooepidemicus is an opportunistic pathogen. It has caused a very large economic loss in the swine industry of China and has become a threat to human health. We announce the complete genome sequence of S. equi subsp. zooepidemicus strain ATCC 35246, which provides opportunities to understand its pathogenesis mechanism and genetic basis.
Project description:Strangles is a globally widespread, commonly diagnosed and important infectious disease of equids caused by Streptococcus equi subsp. equi. We performed whole genome sequencing of 19 S. equi isolates collected from imported horses at the Japanese border. Of these isolates, 15 isolates were obtained from clinical cases and 4 were from subclinical cases. The 19 isolates were grouped into 3 Bayesian analysis of population structure (BAPS) groups by the core genome single nucleotide polymorphism analysis corresponding to exporting country, SeM typing, or exporter of the horses. The 19 isolates possessed same pathogenic genes regardless of clinical status in imported horses and no antimicrobial resistance genes. The disease status of the horses may rather reflect the prior exposure of animals with sub-clinical infection to S. equi.