title: The role of the bacterial membrane protein ActA in immunity and protection against Listeria monocytogenes.
abstract: ActA, an essential virulence factor of Listeria monocytogenes, is an integral membrane protein that is required for intracellular motility, cell-to-cell spread, and rapid dissemination of the bacteria in the infected host. To reveal cytotoxic T cell responses against ActA we introduced a recombinant soluble form of ActA into the MHC class I-processing compartment of APC using a variant of listeriolysin mutated within its immunodominant MHC class I epitope. With this experimental system we demonstrate that T cells are induced against ActA during a sublethal infection with L. monocytogenes. However, adoptively transferred cytotoxic CD8+ T cells specific for ActA did not protect mice against a subsequent challenge with this pathogen. This was due to an inability of APC to present ActA by either MHC class I or class II molecules as long as ActA remained tethered to the surface of intracellular viable bacteria. ActA was only presented when L. monocytogenes were engineered to secrete ActA or when the bacteria were killed by antibiotics during the assay. These findings raise questions on the general use of membrane proteins of pathogens as candidates for subunit vaccines.
authors.affiliation: Division of Cell Biology and Immunobiology, Gesellschaft für Biotechnologische Forschung-National Research Center for Biotechnology, Braunschweig, Germany. ada@gbf.de
authors.forename: A
authors.initials: A
authors.lastname: Darji
authors.forename: D
authors.initials: D
authors.lastname: Bruder
authors.forename: S
authors.initials: S
authors.lastname: zur Lage
authors.forename: B
authors.initials: B
authors.lastname: Gerstel
authors.forename: T
authors.initials: T
authors.lastname: Chakraborty
authors.forename: J
authors.initials: J
authors.lastname: Wehland
authors.forename: S
authors.initials: S
authors.lastname: Weiss
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D017951:Antigen Presentation; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D001427:Bacterial Toxins; D001428:Bacterial Vaccines / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D005260:Female; D006360:Heat-Shock Proteins / Q000235:genetics / Q000276:immunology; D006460:Hemolysin Proteins / Q000235:genetics / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D008089:Listeria monocytogenes / Q000276:immunology*; D008088:Listeriosis / Q000276:immunology* / Q000517:prevention & control*; D008213:Lymphocyte Activation / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D012995:Solubility; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000637:transplantation
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D001428:Bacterial Vaccines; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D008565:Membrane Proteins; C072980:actA protein, Listeria monocytogenes; C038705:hlyA protein, Listeria monocytogenes