title: Identification of CD8 T-lymphocyte epitopes in OmpB of Rickettsia conorii.
abstract: The 1.2-kb DNA fragment of the Rickettsia conorii outer membrane protein B gene (OmpB(451-846)) was subcloned using site-specific PCR primers and expressed as six smaller fragments: OmpB(458-652), OmpB(595-744), OmpB(595-654), OmpB(645-692), OmpB(689-744), and OmpB(739-848). NCTC cells transfected with a mammalian expression vector expressing the fragments OmpB(689-744) and OmpB(739-848) stimulated immune anti-R. conorii CD8 T lymphocytes, suggesting the presence of CD8 T-lymphocyte-stimulating epitopes on these fragments. In order to further characterize the CD8 T-lymphocyte-stimulatory elements, CD8 T-lymphocyte epitopes on OmpB(689-744) and OmpB(739-848) were mapped by overlapping synthetic peptides. The ability of these synthetic peptides to stimulate immune CD8 T lymphocytes was determined by gamma interferon (IFN-gamma) production and cell proliferation after incubation with simian virus 40-transformed murine vascular endothelial cells in the presence of a 20 micro M solution of each synthetic peptide. Five synthetic peptides, SKGVNVDTV (OmpB(708-716)), ANVGSFVFN (OmpB(735-743)), IVSGTVGGQ (OmpB(749-757)), ANSTLQIGG (OmpB(789-797)), and IVEFVNTGP (OmpB(812-820)), induced secretion of IFN-gamma at significantly higher levels than the controls. Three of these five peptides, SKGVNVDTV (OmpB(708-716)), ANSTLQIGG (OmpB(789-797)), and IVEFVNTGP (OmpB(812-820)), also stimulated the proliferation of immune CD8 T lymphocytes. Significantly higher levels of specific cytotoxic T-lymphocyte killing were observed with the same three synthetic peptides, SKGVNVDTV (OmpB(708-716)), ANSTLQIGG (OmpB(789-797)), and IVEFVNTGP (OmpB(812-820)).
authors.affiliation: Department of Pathology, WHO Collaborating Center for Tropical Diseases, University of Texas Medical Branch at Galveston, Galveston, Texas 77555-0609, USA.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.forename: C Marcela
authors.initials: CM
authors.lastname: Díaz-Montero
authors.forename: Gustavo
authors.initials: G
authors.lastname: Valbuena
authors.forename: Xue-Jie
authors.initials: XJ
authors.lastname: Yu
authors.forename: Juan P
authors.initials: JP
authors.lastname: Olano
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Feng
authors.forename: David H
authors.initials: DH
authors.lastname: Walker
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D003001:Cloning, Molecular; D018984:Epitopes, T-Lymphocyte; D015234:HLA-A Antigens / Q000276:immunology; D007371:Interferon-gamma / Q000096:biosynthesis; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D010446:Peptide Fragments / Q000276:immunology; D020114:Rickettsia conorii / Q000276:immunology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D018984:Epitopes, T-Lymphocyte; D015234:HLA-A Antigens; D010446:Peptide Fragments; D007371:Interferon-gamma