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PubMed2000

Control of strangles outbreaks by isolation of guttural pouch carriers identified using PCR and culture of Streptococcus equi.

Previous use of repeated nasopharyngeal swabbing and culture of Streptococcus equi showed that healthy carriers developed in more than 50% of 'strangles' outbreaks. The guttural pouches were the only detectable site of S. equi colonisation on endoscopic examination of horses during one of these outbreaks and S. equi was sometimes not detected by culture of nasopharyngeal swabs from carriers for up to 2 or 3 months before nasal shedding resumed sporadically. A more sensitive way of detecting S. equi on swabs from established guttural pouch carriers was therefore required. Conveniently selected 'strangles' outbreaks were investigated in detail using endoscopy, in order to develop and assess a suitable polymerase chain reaction (PCR) test. We report here 3 protracted 'strangles' outbreaks on different kinds of establishments in which between 29 and 52% of sampled horses were infected as detected by culture and/or PCR. Of the infected horses, between 9 and 44% were identified as carrying S. equi after clinical signs had disappeared and the predominant site of carriage was the guttural pouch. Prolonged carriage of S. equi, which lasted up to 8 months, did not cease spontaneously before treatment was initiated to eliminate the infections. The detection and isolation of the carriers, in conjunction with strict hygiene measures, apparently resulted in the control of the outbreaks and allowed the premises to return to normal activity. Comparing PCR and culture, many more swabs were found to be positive using PCR (56 vs. 30% of 61 swabs). Similar results were obtained for guttural pouch samples from 12 established carriers (PCR 76% and culture 59%). These results from repeated samples from relatively few animals need confirming using more long-term carriers. PCR can also detect dead organisms and is, therefore, liable to yield false positive results. Despite this drawback, it is argued that PCR provides a potentially useful adjunct to culture of nasopharyngeal swabs in the detection of asymptomatic carriers of S. equi following outbreaks of 'strangles'.

Animals↗
PubMed2006

Se18.9, an anti-phagocytic factor H binding protein of Streptococcus equi.

Evasion of phagocytosis is an important virulence determinant of Streptococcus equi (S. equi subsp. equi), the cause of equine strangles and distinguishes it from the closely related but much less virulent S. zooepidemicus (S. equi subsp. zooepidemicus). We describe Se18.9, a novel H factor binding protein secreted by S. equi but not by S. zooepidemicus that reduces deposition of C3 on the bacterial surface and significantly reduces the bactericidal activity of equine neutrophils suspended in normal serum for both S. equi and S. zooepidemicus. Se18.9 is secreted abundantly by actively dividing cells and is also bound to the bacterial surface. Strong serum and mucosal antibody responses are elicited in S. equi infected horses. Although a gene identical to se18.9 was not detected in S. zooepidemicus, sequences encoding proteins of similar size with similar signal peptide sequences were found in 3 of 12 randomly selected strains. Since Se18.9 is unique to S. equi, and immunoreactive with convalescent sera and mucosal IgA, it has potential for immunodiagnosis and for study of mucosal antibody response to S. equi.

Animals↗
PubMed1996

Fibronectin-binding protein of Streptococcus equi subsp. zooepidemicus.

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.

Adhesins, Bacterial↗
PubMed2006

Identification and characterization of the heme-binding proteins SeShp and SeHtsA of Streptococcus equi subspecies equi.

BACKGROUND: Heme is a preferred iron source of bacterial pathogens. Streptococcus equi subspecies equi is a bacterial pathogen that causes strangles in horses. Whether S. equi has a heme acquisition transporter is unknown. RESULTS: An S. equi genome database was blasted with the heme binding proteins Shp and HtsA of Streptococcus pyogenes, and found that S. equi has the homologue of Shp (designated SeShp) and HtsA (designated SeHtsA). Tag-free recombinant SeShp and SeHtsA and 6xHis-tagged SeHtsA (SeHtsAHis) were prepared and characterized. Purified holoSeShp and holoSeHtsA bind Fe(II)-protoporphyrin IX (heme) and Fe(III)-protoporphyrin IX (hemin) in a 1:1 stoichiometry, respectively, and are designated hemoSeShp and hemiSeHtsA. HemiSeShp and hemiSeHtsAHis can be reconstituted from apoSeShp and apoSeHtsAHis and hemin. HemoSeShp is stable in air and can be oxidized to hemiSeShp by ferricyanide. HemiSeHtsA can be reduced into hemoSeHtsA, which autoxidizes readily. HemoSeShp rapidly transfers its heme to apoSeHtsAHis. In addition, hemoSeShp can also transfer its heme to apoHtsA, and hemoShp is able to donate heme to apoSeHtsAHis. CONCLUSION: The primary structures, optical properties, oxidative stability, and in vitro heme transfer reaction of SeShp and SeHtsA are very similar to those of S. pyogenes Shp and HtsA. The data suggest that the putative cell surface protein SeShp and lipoprotein SeHtsA are part of the machinery to acquire heme in S. equi. The results also imply that the structure, function, and functional mechanism of the heme acquisition machinery are conserved in S. equi and S. pyogenes.

Amino Acid Sequence↗
PubMed2006

An outbreak of Streptococcus equi subspecies zooepidemicus associated with consumption of fresh goat cheese.

BACKGROUND: Streptococcus equi subspecies zooepidemicus is a rare infection in humans associated with contact with horses or consumption of unpasteurized milk products. On October 23, 2003, the National Public Health Institute was alerted that within one week three persons had been admitted to Tampere University Central Hospital (TaYS) because of S. equi subsp. zooepidemicus septicaemia. All had consumed fresh goat cheese produced in a small-scale dairy located on a farm. We conducted an investigation to determine the source and the extent of the outbreak. METHODS: Cases were identified from the National Infectious Disease Register. Cases were persons with S. equi subsp. zooepidemicus isolated from a normally sterile site who had illness onset 15.9-31.10.2003. All cases were telephone interviewed by using a standard questionnaire and clinical information was extracted from patient charts. Environmental and food specimens included throat swabs from two persons working in the dairy, milk from goats and raw milk tank, cheeses made of unpasteurized milk, vaginal samples of goats, and borehole well water. The isolates were characterized by ribotyping and pulsed-field gel electrophoresis (PFGE). RESULTS: Seven persons met the case definition; six had septicaemia and one had purulent arthritis. Five were women; the median age was 70 years (range 54-93). None of the cases were immunocompromized and none died. Six cases were identified in TaYS, and one in another university hospital in southern Finland. All had eaten goat cheese produced on the implicated farm. S. equi subsp. zooepidemicus was isolated from throat swabs, fresh goat cheese, milk tank, and vaginal samples of one goat. All human and environmental strains were indistinguishable by ribotyping and PFGE. CONCLUSION: The outbreak was caused by goat cheese produced from unpasteurized milk. Outbreaks caused by S. equi subsp. zooepidemicus may not be detected if streptococcal strains are only typed to the group level. S. equi subsp. zooepidemicus may be a re-emerging disease if unpasteurized milk is increasingly used for food production. Facilities using unpasteurized milk should be carefully monitored to prevent this type of outbreaks.

Aged↗
PubMed2005

Severe acute rhabdomyolysis associated with Streptococcus equi infection in four horses.

Four Quarter Horses (9 months to 7 years of age) with submandibular lymphadenopathy and firm muscles (palpation of which elicited signs of pain) were evaluated; in general, the horses had a stiff gait, and 3 horses became recumbent. Streptococcus equi was cultured from aspirates of lymph nodes or samples of purulent material collected from the auditory tube diverticula. Once the horses were recumbent, their condition deteriorated rapidly despite aggressive antimicrobial and antiinflammatory treatment, necessitating euthanasia within 24 to 48 hours. One horse did not become recumbent and recovered completely. Among the 4 horses, common clinicopathologic findings included neutrophilia, hyperfibrinogenemia, and high serum activities of creatine kinase and aspartate aminotransferase. Necropsies of the 3 euthanatized horses revealed large, pale areas most prominent in the semimembranosus, semitendinosus, sublumbar, and gluteal muscles that were characterized histologically by severe acute myonecrosis and macrophage infiltration of necrotic myofibers. Streptococcus equi was identified in sections of affected muscle by use of immunofluorescent stains for Lancefield group C carbohydrate and S. equi M protein. In the 4 horses of this report, acute severe rhabdomyolysis without clinical evidence of muscle atrophy or infarction was associated with S. equi infection; rhabdomyolysis was attributed to either an inflammatory cascade resembling streptococcal toxic shock or potentially direct toxic effects of S. equi within muscle tissue.

Acute Disease↗
PubMed2004

Streptococcus equi subsp. ruminatorum subsp. nov., isolated from mastitis in small ruminants.

Six isolates of an unknown Gram-positive, catalase-negative, chain-forming, coccus-shaped organism isolated from ovine and caprine mastitis were characterized by phenotypic and molecular taxonomic methods. On the basis of cellular morphology and the results of biochemical tests, the organism was tentatively identified as a streptococcal species. Comparative 16S rRNA gene sequencing studies confirmed that the organism is a member of the genus Streptococcus, with Streptococcus equi as its closest phylogenetic relative (98.8 % similarity). DNA-DNA pairing studies showed that the unidentified organism displayed more than 70 % relatedness to the type strains of S. equi subsp. equi and subsp. zooepidemicus. Despite the relatively high DNA-DNA reassociation values, biotyping and ribotyping allowed clear differentiation of the unknown bacterium from the two recognized subspecies of S. equi. On the basis of phenotypic and molecular genetic evidence, it is proposed that the unknown Streptococcus isolates from ovine and caprine mastitis be classified as a novel subspecies, Streptococcus equi subsp. ruminatorum subsp. nov. The type strain is CECT 5772(T) (=CCUG 47520(T)=Mt 167(T)).

Animals↗
PubMed2006

Protective effect of vaccination with recombinant proteins from Streptococcus equi subspecies equi in a strangles model in the mouse.

A mouse model resembling Streptococcus equi subspecies equi infection in the horse, strangles, was used to assess the protective effect of vaccination with selected recombinant proteins from S. equi subsp. equi. After challenge the infection was monitored by weight loss and by nasal colonisation with S. equi subsp. equi. Vaccination with a collagen-binding protein (CNE) and a collagen-like protein (SclC) resulted in protective antibodies, whereas a novel fibronectin-binding protein (FNEB) did not. Co-administration of CNE with EAG, a poorly immunogenic alpha2-macroglobulin-, albumin- and immunoglobulin G-binding protein, resulted in a significant synergistic effect and enhanced the protective immune response against EAG.

Animals↗
PubMed2007

Characterization of the new beta-glucuronidase from Streptococcus equi subsp. zooepidemicus.

Recently, a new gene encoding beta-glucuronidase from Streptococcus equi subsp. zooepidemicus (SEZ) was identified and expressed in Escherichia coli. In this paper, the characterization of the enzyme is described. Specific enzyme activity was 120,000 U/mg purified protein at 37 degrees C and pH = 7.0. The temperature and pH value, at which the enzyme has the highest specific activity, were determined and were found to be approximately 52 degrees C and 5.6, respectively. The mutant strain SEZ glcHis was designed for the efficient isolation of beta-glucuronidase from S. equi subsp. zooepidemicus. It was observed that the specific activity of beta-glucuronidase in the cytoplasmic extract of a mutated strain was about 45% lower than in the cytoplasmic extract of a wild-type strain. The specific activity of purified beta-glucuronidase from SEZ glcHis was four times as low as beta-glucuronidase purified from E. coli. Comparing the specific activity of purified streptococcal beta-glucuronidase from E. coli with E. coli beta-glucuronidase (the enzyme with the highest specific activity was supplied by Sigma), the former is 1.8 higher than the latter.

Cloning, Molecular↗
PubMed1999

SFS, a novel fibronectin-binding protein from Streptococcus equi, inhibits the binding between fibronectin and collagen.

The obligate parasitic bacterium Streptococcus equi subsp. equi is the causative agent of strangles, a serious disease of the upper respiratory tract in horses. In this study we have, using shotgun phage display, cloned from S. equi subsp. equi and characterized a gene, called sfs, encoding a protein termed SFS, representing a new type of fibronectin (Fn)-binding protein. The sfs gene was found to be present in all 50 isolates of S. equi subsp. equi tested and in 41 of 48 S. equi subsp. zooepidemicus isolates tested. The sfs gene is down-regulated during growth in vitro compared to fnz, a previously characterized gene encoding an Fn-binding protein from S. equi subsp. zooepidemicus. Sequence comparisons revealed no similarities to previously characterized Fn-binding proteins, but high scores were obtained against collagen. Besides similarity due to the high content of glycine, serine, and proline residues present in both proteins, there was a nine-residue motif present both in collagen and in the Fn-binding domain of SFS. By searching the Oklahoma S. pyogenes database, we found that this motif is also present in a potential cell surface protein from S. pyogenes. Protein SFS was found to inhibit the binding between Fn and collagen in a concentration-dependent way.

Adhesins, Bacterial↗
PubMed2005

Increase in hyaluronic acid production by Streptococcus equi subsp. zooepidemicus strain deficient in beta-glucuronidase in laboratory conditions.

Streptococcus equi subsp. zooepidemicus is known to produce a hyaluronic acid capsule to resist the host immune defense. As the structure of the polysaccharide is identical to the one produced by humans, the bacteria S. equi subsp. zooepidemicus is used in biotechnological production of hyaluronic acid. In our laboratory we prepared mutated strains that are beta-glucuronidase deficient. Comparing the wild-type strain, which is positive in beta-glucuronidase activity, with the mutated strains named clone1 and clone2 in laboratory conditions, we observed that beta-glucuronidase influences the production of hyaluronic acid considerably and the molecular weight of hyaluronan slightly. The production of hyaluronic acid by the mutated strains is higher by approximately 20% and the molecular weight is larger by about 2%. The significant increase in the production of hyaluronic acid and the slight increase in the molecular weight are probably caused by an absence of free beta-glucuronic acid, due to its removal from the non-reducing termini of the polysaccharide by beta-glucuronidase. The presence of free beta-glucuronic acid would likely induce the expression of the beta-glucuronic-acid-utilizing operon, which in turn would reflect into a misuse of energy in the glucose-rich media.

Chromatography, Gel↗
PubMed2006

Mutation of the maturase lipoprotein attenuates the virulence of Streptococcus equi to a greater extent than does loss of general lipoprotein lipidation.

Streptococcus equi is the causative agent of strangles, a prevalent and highly contagious disease of horses. Despite the animal suffering and economic burden associated with strangles, little is known about the molecular basis of S. equi virulence. Here we have investigated the contributions of a specific lipoprotein and the general lipoprotein processing pathway to the abilities of S. equi to colonize equine epithelial tissues in vitro and to cause disease in both a mouse model and the natural host in vivo. Colonization of air interface organ cultures after they were inoculated with a mutant strain deficient in the maturase lipoprotein (DeltaprtM(138-213), with a deletion of nucleotides 138 to 213) was significantly less than that for cultures infected with wild-type S. equi strain 4047 or a mutant strain that was unable to lipidate preprolipoproteins (Deltalgt(190-685)). Moreover, mucus production was significantly greater in both wild-type-infected and Deltalgt(190-685)-infected organ cultures. Both mutants were significantly attenuated compared with the wild-type strain in a mouse model of strangles, although 2 of 30 mice infected with the Deltalgt(190-685) mutant did still exhibit signs of disease. In contrast, only the DeltaprtM(138-213) mutant was significantly attenuated in a pony infection study, with 0 of 5 infected ponies exhibiting pathological signs of strangles compared with 4 of 4 infected with the wild-type and 3 of 5 infected with the Deltalgt(190-685) mutant. We believe that this is the first study to evaluate the contribution of lipoproteins to the virulence of a gram-positive pathogen in its natural host. These data suggest that the PrtM lipoprotein is a potential vaccine candidate, and further investigation of its activity and its substrate(s) are warranted.

Alleles↗
PubMed2000

Induction of mucosal and systemic antibody specific for SeMF3 of Streptococcus equi by intranasal vaccination using a sucrose acetate isobutyrate based delivery system.

Streptococcus equi causes equine strangles, a highly contagious disease of the upper respiratory tract. The antiphagocytic surface protein SeM is strongly immunogenic and evokes mucosal and systemic antibodies during convalescence. The present study investigated the potential of sucrose acetate isobutyrate (SAIB); a high viscosity excipient that provides controlled release of biologically active substances, to enhance antibody responses following intranasal immunization of horses with a 108 a.a. peptide of SeM (SeMF3). SeMF3-SAIB was administered intranasally to each of the 11 adult horses on days 0 and 28. A second group of seven horses was vaccinated with SeMF3 alone. SAIB enhanced the mucosal and systemic immunogenicity of SeMF3, whereas SeMF3 by itself stimulated only a shortlived mucosal IgA and no systemic response. Moreover, nasal mucosal responses of horses immunized with SeMF3-SAIB were qualitatively and quantitatively similar to those observed in convalescent horses and involved similar linear epitopes of SeM. Epitope analysis also suggested that the nasal response was different from that observed in serum. A booster response was obtained after the second vaccination. These results suggest that SAIB has potential as a vehicle for intranasal immunization of horses with antigenic peptides.

Administration, Intranasal↗
PubMed1977

Bacteriophages of Streptococcus equi.

Bacteriophages were isolated from twelve lysogenic strains of Streptococcus equi. Based on sensitivity data and antiserum neutralization tests, the phage isolates were divided into two distinct but related groups. All twelve phage change the colonial morphology of S. equi from mucoid to matt. Possible phage-mediated effects on S. equi virulence are discussed.

Bacteriophage Typing↗
PubMed2001

Comparison of the fibronectin-binding protein FNE from Streptococcus equi subspecies equi with FNZ from S. equi subspecies zooepidemicus reveals a major and conserved difference.

The gene fnz from Streptococcus equi subspecies zooepidemicus encodes a cell surface protein that binds fibronectin (Fn). Fifty tested isolates of S. equi subspecies equi all contain DNA sequences with similarity to fnz. This work describes the cloning and sequencing of a gene, designated fne, with similarity to fnz from two S. equi subspecies equi isolates. The DNA sequences were found to be identical in the two strains, and sequence comparison of the fne and fnz genes revealed only minor differences. However, one base deletion was found in the middle of the fne gene and eight base pairs downstream of the altered reading frame there is a stop codon. An Fn-binding protein was purified from the growth medium of a subspecies equi culture. Determination of the NH(2)-terminal amino acid sequence and molecular mass, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, revealed that the purified protein is the gene product of the 5'-terminal half of fne. Fn-binding activity has earlier only been found in the COOH-terminal half of FNZ. By the use of a purified recombinant protein containing the NH(2) half of FNZ, we provide here evidence that this half of the protein also harbors an Fn-binding domain.

Adhesins, Bacterial↗
PubMed1997

Serum and mucosal antibody isotype responses to M-like protein (SeM) of Streptococcus equi in convalescent and vaccinated horses.

Equine strangles, caused by the clonal pathogen Streptococcus equi, is a source of serious economic loss despite the widespread use of commercial vaccines. The anti-phagocytic 58 kDa M-like protein (SeM) is an important protective antigen. The objective of this study was to define differences, if any, between SeM-specific convalescent serum and mucosal IgA and IgG subisotypes and those induced by vaccination with commercial strangles vaccine. SeM-specific opsonophagocytic IgGb was the predominant serum antibody in horses intramuscularly vaccinated or recently recovered from infection. Infection also induced high levels of specific opsonophagocytic serum IgGa during and shortly after S. equi infection whereas vaccination stimulated only low levels of serum IgGa. Specific serum IgGc and opsonophagocytic IgA were present at very low levels following infection or vaccination. A strong specific mucosal antibody response occurred during the acute and convalescent phases of infection whereas vaccinated horses made no mucosal response. Specific IgGb was generally predominant in nasopharyngeal washings during the acute phase but was replaced by specific IgA during convalescence. SeM-specific mucosal IgGa and IgG(T) but not IgGc were detected only during the acute and early convalescent phase. The results therefore indicate that vaccination, although inducing SeM-specific serum isotype responses qualitatively and quantitatively similar to those seen in convalescence, did not induce mucosal responses. This suggests that mucosal immunity may be important in acquired resistance to strangles.

Animals↗
PubMed1975

The cell surface antigens of Streptococcus equi.

An analysis of the cell surface antigens of Streptococcus equi is presented. Following extraction from cell walls, whole cells and hyaluronidase treated cells the immunoprecipitation patterns of the intact and protease treated components were developed with rabbit anti serum against S. equi. It was determined by mouse protection tests that the specificity of protective antibodies was directed toward a trypsin labile antigen. The presence of antigens similar to those designated M and R in Group A streptococci were found in S. equi.

Absorption↗