| 1. |
- Bergmann, René, et al.
(författare)
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Prominent Binding of Human and Equine Fibrinogen to Streptococcus equi subsp. zooepidemicus Is Mediated by Specific SzM Types and Is a Distinct Phenotype of Zoonotic Isolates
- 2020
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Ingår i: Infection and Immunity. - 1098-5522. ; 88:1
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus equi subsp. zooepidemicus is an important pathogen in horses that causes severe diseases such as pneumonia and abortion. Furthermore, it is a zoonotic agent, and contact with horses is a known risk factor. In this study, we investigated the working hypothesis that the zoonotic potential varies among S. equi subsp. zooepidemicus strains in association with differences in M-like protein-mediated binding of host plasma proteins. We demonstrate via in-frame deletion mutagenesis of two different S. equi subsp. zooepidemicus strains that the M-like protein SzM is crucial for the binding of fibrinogen to the bacterial surface and for survival in equine and human blood. S. equi subsp. zooepidemicus isolates of equine and human origins were compared with regard to SzM sequences and binding of equine and human fibrinogens. The N-terminal 216 amino acids of the mature SzM were found to exhibit a high degree of diversity, but the majority of human isolates grouped in three distinct SzM clusters. Plasma protein absorption assays and flow cytometry analysis revealed that pronounced binding of human fibrinogen is a common phenotype of human S. equi subsp. zooepidemicus isolates but much less so in equine S. equi subsp. zooepidemicus isolates. Furthermore, binding of human fibrinogen is associated with specific SzM types. These results suggest that SzM-mediated binding of human fibrinogen is an important virulence mechanism of zoonotic S. equi subsp. zooepidemicus isolates.
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| 2. |
- Seele, Jana, et al.
(författare)
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The immunoglobulin M-degrading enzyme of Streptococcus suis, Ide(Ssuis), is involved in complement evasion
- 2015
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Ingår i: Veterinary research (Print). - : Springer Science and Business Media LLC. - 0928-4249 .- 1297-9716. ; 46
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus (S.) suis is one of the most important pathogens in pigs causing meningitis, arthritis, endocarditis and serositis. Furthermore, it is also an emerging zoonotic agent. In our previous work we identified a highly specific IgM protease in S. suis, designated IdeSsuis. The objective of this study was to characterize the function of IdeSsuis in the host-pathogen interaction. Edman-sequencing revealed that Ide(Ssuis) cleaves the heavy chain of the IgM molecule between constant domain 2 and 3. As the C1q binding motif is located in the C3 domain, we hypothesized that IdeSsuis is involved in complement evasion. Complement-mediated hemolysis induced by porcine hyperimmune sera containing erythrocyte-specific IgM was abrogated by treatment of these sera with recombinant IdeSsuis. Furthermore, expression of IdeSsuis reduced IgM-triggered complement deposition on the bacterial surface. An infection experiment of prime-vaccinated growing piglets suggested attenuation in the virulence of the mutant 10 Delta IdeSsuis. Bactericidal assays confirmed a positive effect of IdeSsuis expression on bacterial survival in porcine blood in the presence of high titers of specific IgM. In conclusion, this study demonstrates that IdeSsuis is a novel complement evasion factor, which is important for bacterial survival in porcine blood during the early adaptive (IgM-dominated) immune response.
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