title: Identification and characterization of a new cell surface protein possessing factor H-binding activity in the swine pathogen and zoonotic agent Streptococcus suis.
abstract: Streptococcus suis is a major swine pathogen and an emerging zoonotic agent. The ability of pathogenic bacteria to bind the complement regulator factor H on their cell surface may allow them to avoid complement attack and phagocytosis. The aim of this study was to characterize a new cell surface protein possessing factor H-binding activity in S. suis serotype 2. The capacity of S. suis to bind the complement regulator factor H on its surface was demonstrated by ELISA. Using a factor I-cofactor assay, it was found that the functional activity of factor H bound to S. suis was kept. Since the product of gene SSU0186 in S. suis P1/7 shared similarity with a Streptococcus pneumoniae protein (named PspC) possessing factor H-binding activity, it was proposed as a putative factor H receptor in S. suis. SSU0186 has a 1686 bp open reading frame encoding a 561 amino acid protein containing the Gram-positive cell wall anchoring motif (LPXTG) at the carboxy-terminal, an amino-terminal signal sequence, an α-helix domain, a proline-rich region and a G5 domain. The SSU0186 gene was cloned in Escherichia coli and the purified recombinant factor H-binding protein showed a molecular mass of 95 kDa, as determined by SDS-PAGE. The protein possessed the functional property of binding factor H. Sera from S. suis-infected pigs reacted with the recombinant factor H receptor, suggesting that it is produced during the course of infections. In conclusion, we identified a novel S. suis cell surface protein that binds the complement factor H. This cell surface protein may help S. suis to resist complement attack and phagocytosis and contribute to pathogenesis.
authors.affiliation: Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Katy
authors.initials: K
authors.lastname: Vaillancourt
authors.affiliation: Centre de Recherche en Infectiologie Porcine (CRIP), Fonds de Recherche du Québec - Nature et Technologies (FRQNT), Quebec City, Quebec, Canada.|Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Bonifait
authors.affiliation: Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Louis
authors.initials: L
authors.lastname: Grignon
authors.affiliation: Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Frenette
authors.affiliation: Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada.|Centre de Recherche en Infectiologie Porcine (CRIP), Fonds de Recherche du Québec - Nature et Technologies (FRQNT), Quebec City, Quebec, Canada.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Gottschalk
authors.affiliation: Centre de Recherche en Infectiologie Porcine (CRIP), Fonds de Recherche du Québec - Nature et Technologies (FRQNT), Quebec City, Quebec, Canada.|Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Grenier
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D017242:Complement Factor H / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017011:Streptococcus suis / Q000235:genetics / Q000378:metabolism*; D013552:Swine; D015047:Zoonoses / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D017242:Complement Factor H