title: A novel fibronectin-binding protein of Streptococcus suis serotype 2 contributes to epithelial cell invasion and in vivo dissemination.
abstract: Streptococcus suis serotype 2 (SS2) is an important pathogen with zoonotic potential. In this study, a novel in vivo induced protein Ssa, encoded by the functionally unknown gene SSU05_1311, was identified as a surface anchored fibronectin-binding protein. The recombinant Ssa as well as its truncated proteins harboring the N-terminal domain (residues 33-153) could bind to human fibronectin with high-affinity. Isogenic knockout of ssa in SS2 led to decrease of bacterial binding to immobilized fibronectin. SS2 Δssa mutant showed reduced adherence and invasion of human pharyngeal epithelial (HEp-2) cells compared to the wild type strain. Heterologous surface display of Ssa fibronectin-binding domain in Escherichia coli enhanced the bacterial attachment and entry to HEp-2 cells. Less SS2 Δssa mutants than the wild type strain were recovered from the blood and brains of the Balb/c mice infected intranasally. But there was no significant difference between the wild type and the mutant on phagocytosis by macrophages (RAW264.7) and bacterial killing by murine PMNs under opsonizing condition. Our data suggest that Ssa is an important virulence factor for SS2 crossing the mucosal epithelia to disseminate in vivo.
authors.affiliation: Division of Animal Infectious Diseases in State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Yun
authors.initials: Y
authors.lastname: Wan
authors.forename: Zui
authors.initials: Z
authors.lastname: Tao
authors.forename: Huanchun
authors.initials: H
authors.lastname: Chen
authors.forename: Rui
authors.initials: R
authors.lastname: Zhou
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001422:Bacterial Adhesion; D003001:Cloning, Molecular; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009092:Mucous Membrane / Q000166:cytology / Q000382:microbiology*; D010614:Pharynx / Q000166:cytology / Q000382:microbiology; D011485:Protein Binding; D013290:Streptococcal Infections / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D017011:Streptococcus suis / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D037521:Virulence Factors; C078635:fibronectin-binding proteins, bacterial