title: CAMP factor is not essential for systemic virulence of Group B Streptococcus.
abstract: The Gram-positive pathogen Group B Streptococcus (GBS) is the leading cause of bacterial pneumonia, sepsis, and meningitis in human newborns. GBS elaborates a pore-forming toxin known as CAMP factor that synergizes with Staphylococcus aureus beta-toxin, generating a co-hemolytic reaction useful in identification of GBS in the clinical laboratory. To evaluate the indirect evidence implicating CAMP factor in GBS pathogenesis, the cfb gene encoding the pore-forming cytotoxin was deleted by precise allelic replacement. The virulence properties of the CAMP factor mutant were then explored by a series of in vitro and in vivo assays. Compared to wild-type, the isogenic GBS Deltacfb mutant demonstrated equivalent phagocyte resistance and endothelial cell invasiveness and also retained full virulence in a mouse model of infection. Our data suggest that CAMP factor expressed in its native context is not essential for systemic virulence of GBS.
authors.affiliation: Division of Pediatric Pharmacology and Drug Discovery, School of Medicine, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0687, USA.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Hensler
authors.forename: Darin
authors.initials: D
authors.lastname: Quach
authors.forename: Chia-Jun
authors.initials: CJ
authors.lastname: Hsieh
authors.forename: Kelly S
authors.initials: KS
authors.lastname: Doran
authors.forename: Victor
authors.initials: V
authors.lastname: Nizet
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins / Q000502:physiology*; D054804:Cathelicidins; D005816:Genetic Complementation Test; D006460:Hemolysin Proteins / Q000502:physiology*; D006801:Humans; D008264:Macrophages; D051379:Mice; D008810:Mice, Inbred C57BL; D016297:Mutagenesis, Site-Directed / Q000379:methods; D009154:Mutation; D010641:Phenotype; D013290:Streptococcal Infections; D013292:Streptococcus agalactiae / Q000235:genetics / Q000472:pathogenicity*; D016019:Survival Analysis; D013997:Time Factors; D014774:Virulence / Q000502:physiology*
chemical_list: D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; C039092:CAMP protein, Streptococcus; D054804:Cathelicidins; D006460:Hemolysin Proteins