The immunoglobulin M-degrading enzyme of Streptococcus suis, IdeSsuis, is involved in complement evasion.
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 Ide(Ssuis) . The objective of this study was to characterize the function of Ide(Ssuis) 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 Ide(Ssuis) 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 Ide(Ssuis) . Furthermore, expression of Ide(Ssuis) 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 10Δide(Ssuis). Bactericidal assays confirmed a positive effect of Ide(Ssuis) expression on bacterial survival in porcine blood in the presence of high titers of specific IgM. In conclusion, this study demonstrates that Ide(Ssuis) is a novel complement evasion factor, which is important for bacterial survival in porcine blood during the early adaptive (IgM-dominated) immune response.
Institute for Microbiology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, 30173, Hannover, Germany. jana_seele@gmx.de.
Jana
J
Seele
Department of Pathology, University of Veterinary Medicine Hannover, 30559, Hannover, Germany. andreas.beineke@tiho-hannover.de.
Andreas
A
Beineke
Institute for Microbiology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, 30173, Hannover, Germany. lena.hillermann@web.de.
Lena-Maria
LM
Hillermann
Department of Structure and Function of Proteins, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany. beate.jaschok-kentner@helmholtz-hzi.de.
Beate
B
Jaschok-Kentner
Department of Molecular Biology and Umeå Centre for Microbial Research, Umeå University, 90187, Umeå, Sweden. Ulrich.von-Pawel@molbiol.umu.se.
Ulrich
U
von Pawel-Rammingen
Institute for Microbiology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, 30173, Hannover, Germany. Peter.Valentin@tiho-hannover.de.
Peter
P
Valentin-Weigand
Institute for Bacteriology and Mycology, Centre of Infectious Diseases, College of Veterinary Medicine, University Leipzig, An den Tierkliniken 29, 04103, Leipzig, Germany. christoph.baums@vetmed.uni-leipzig.de.
Christoph Georg
CG
Baums
D000818:Animals; D016667:Bacterial Capsules / Q000502:physiology; D001426:Bacterial Proteins / Q000502:physiology*; D003165:Complement System Proteins / Q000502:physiology*; D006460:Hemolysin Proteins / Q000502:physiology*; D054884:Host-Pathogen Interactions; D007113:Immunity, Innate; D007075:Immunoglobulin M / Q000502:physiology*; D013290:Streptococcal Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D017011:Streptococcus suis / Q000502:physiology*; D013552:Swine; D013553:Swine Diseases / Q000276:immunology* / Q000382:microbiology
D001426:Bacterial Proteins; D006460:Hemolysin Proteins; D007075:Immunoglobulin M; D003165:Complement System Proteins