Identification of a novel host-specific IgM protease in Streptococcus suis

• Streptococcus (S.) suis is an important invasive, extracellular pathogen in pigs, which causes meningitis, arthritis, serositis and other diseases. Furthermore, it is also an emerging zoonotic agent. This study was initiated by the finding that IgM degradation products are released after opsonization of S. suis with porcine serum. The objective of this work was to identify and characterize the factor responsible for IgM cleavage. The results showed that a protein of S. suis with high homology to the well characterized IgG endopeptidase of S. pyogenes IdeS (or Mac1) [1, 2], designated IdeSsuis, degrades immunoglobulins (Ig) of the isotype M, but not IgG, IgA or other proteins present in porcine cerebrospinal fluid, joint fluid or serum. Western Blot analysis revealed that IdeSsuis is host-specific as it exclusively cleaves porcine IgM but not IgM from six other species. Flow cytometry and immunofluorescence microscopy demonstrated that this protein modulates binding of IgM to the bacterial surface. Furthermore the isogenic ideSsuis deletion mutant is significantly attenuated in survival in porcine blood [3]. IdeSsuis is the first prokaryotic IgM-specific protease described indicating a novel host-pathogen interaction at an early stage of the host immune response. Furthermore cleavage of porcine IgM by IdeSsuis is the first identified phenotype reflecting functional adaptation of S. suis to pigs as the main host.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Mikrobiologi inom det medicinska området (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Microbiology in the medical area (hsv//eng)

Publication and Content Type

vet (subject category)

art (subject category)