title: Auto-Assembling Detoxified Staphylococcus aureus Alpha-Hemolysin Mimicking the Wild-Type Cytolytic Toxin.
abstract: Staphylococcus aureus alpha-hemolysin (Hla) assembles into heptameric pores on the host cell membrane, causing lysis, apoptosis, and junction disruption. Herein, we present the design of a newly engineered S. aureus alpha-toxin, HlaPSGS, which lacks the predicted membrane-spanning stem domain. This protein is able to form heptamers in aqueous solution in the absence of lipophilic substrata, and its structure, obtained by transmission electron microscopy and single-particle reconstruction analysis, resembles the cap of the wild-type cytolytic Hla pore. HlaPSGS was found to be impaired in binding to host cells and to its receptor ADAM10 and to lack hemolytic and cytotoxic activity. Immunological studies using human sera as well as sera from mice convalescent from S. aureus infection suggested that the heptameric conformation of HlaPSGS mimics epitopes exposed by the cytolytic Hla pore during infection. Finally, immunization with this newly engineered Hla generated high protective immunity against staphylococcal infection in mice. Overall, this study provides unprecedented data on the natural immune response against Hla and suggests that the heptameric HlaPSGS is a highly valuable vaccine candidate against S. aureus.
authors.affiliation: Novartis Vaccines and Diagnostics, now GSK Vaccines, Siena, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Fiaschi
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy.
authors.forename: Benedetta
authors.initials: B
authors.lastname: Di Palo
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Scarselli
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy.
authors.forename: Clarissa
authors.initials: C
authors.lastname: Pozzi
authors.affiliation: Departments of Pediatrics and Microbiology, University of Chicago, Chicago, Illinois, USA.
authors.forename: Kelly
authors.initials: K
authors.lastname: Tomaszewski
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Galletti
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Nardi-Dei
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy.
authors.forename: Letizia
authors.initials: L
authors.lastname: Arcidiacono
authors.affiliation: Novartis Vaccines and Diagnostics, now GSK Vaccines, Siena, Italy.
authors.forename: Ravi P N
authors.initials: RP
authors.lastname: Mishra
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Mori
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Pallaoro
authors.affiliation: Novartis Vaccines and Diagnostics, now GSK Vaccines, Siena, Italy.
authors.forename: Fabiana
authors.initials: F
authors.lastname: Falugi
authors.affiliation: Novartis Vaccines and Diagnostics, now GSK Vaccines, Siena, Italy.
authors.forename: Antonina
authors.initials: A
authors.lastname: Torre
authors.affiliation: Novartis Vaccines and Diagnostics, now GSK Vaccines, Siena, Italy.
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Fontana
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Soriani
authors.affiliation: Departments of Pediatrics and Microbiology, University of Chicago, Chicago, Illinois, USA.
authors.forename: Juliane
authors.initials: J
authors.lastname: Bubeck Wardenburg
authors.affiliation: Novartis Vaccines and Diagnostics, now GSK Vaccines, Siena, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Grandi
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy.
authors.forename: Rino
authors.initials: R
authors.lastname: Rappuoli
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy ilaria.x.ferlenghi@gsk.com fabio.x.bagnoli@gsk.com.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Ferlenghi
authors.affiliation: GSK Vaccines, Research Center, Siena, Italy ilaria.x.ferlenghi@gsk.com fabio.x.bagnoli@gsk.com.
authors.forename: Fabio
authors.initials: F
authors.lastname: Bagnoli
mesh_terms: D000072197:ADAM10 Protein / Q000378:metabolism; D000818:Animals; D001427:Bacterial Toxins / Q000008:administration & dosage / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D003603:Cytotoxins; D000939:Epitopes / Q000276:immunology; D004926:Escherichia coli / Q000235:genetics; D006460:Hemolysin Proteins / Q000008:administration & dosage / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D018716:Molecular Mimicry; D015202:Protein Engineering; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D013203:Staphylococcal Infections / Q000517:prevention & control*; D013209:Staphylococcal Vaccines / Q000276:immunology; D013211:Staphylococcus aureus / Q000737:chemistry / Q000378:metabolism; D014611:Vaccination
chemical_list: D001427:Bacterial Toxins; D003603:Cytotoxins; D000939:Epitopes; D006460:Hemolysin Proteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; D013209:Staphylococcal Vaccines; C021091:staphylococcal alpha-toxin; D000072197:ADAM10 Protein