title: Fhb, a novel factor H-binding surface protein, contributes to the antiphagocytic ability and virulence of Streptococcus suis.
abstract: Streptococcus suis serotype 2 is a Gram-positive bacterium that causes sepsis and meningitis in piglets and humans. The mechanisms of S. suis serotype 2 invasive disease are not well understood. The surface proteins of pathogens usually play important roles in infection and bacterium-host interactions. Here, we identified a novel surface protein that contributed significantly to the virulence of S. suis serotype 2 in a piglet infection model. This protein showed little similarity to other reported proteins and exhibited strong binding activity to human factor H (hFH). It was designated Fhb (factor H-binding protein). The fhb genes found in S. suis serotypes 1, 2, 4, 7, and 9 exhibited molecular polymorphism. Fhb possessed two proline-rich repeat sequences and XPZ domains, and one repeat sequence exhibited a high homology to Bac, an IgA-binding protein of Streptococcus agalactiae. Evidence strongly indicated that fhb-deficient mutants had diminished phagocytosis resistance in bactericidal assays. In addition, Fhb plays important roles in complement-mediated immunity by interacting with hFH. These findings indicated that Fhb is a crucial surface protein contributing to the virulence of S. suis, with important functions in evading innate immune defenses by interaction with host complement regulatory factor hFH.
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
authors.forename: Yaya
authors.initials: Y
authors.lastname: Pian
authors.forename: Shuzhen
authors.initials: S
authors.lastname: Gan
authors.forename: Shujie
authors.initials: S
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Guo
authors.forename: Pingping
authors.initials: P
authors.lastname: Wang
authors.forename: Yuling
authors.initials: Y
authors.lastname: Zheng
authors.forename: Xuehui
authors.initials: X
authors.lastname: Cai
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Jiang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yuan
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017242:Complement Factor H / Q000378:metabolism*; D004195:Disease Models, Animal; D054884:Host-Pathogen Interactions; D006801:Humans; D057131:Immune Evasion; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D010587:Phagocytosis; D011110:Polymorphism, Genetic; D017386:Sequence Homology, Amino Acid; D013290:Streptococcal Infections / Q000382:microbiology / Q000473:pathology; D017011:Streptococcus suis / Q000276:immunology* / Q000472:pathogenicity*; D013552:Swine; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D037521:Virulence Factors; D017242:Complement Factor H