title: Rickettsia rickettsii outer membrane protein YbgF induces protective immunity in C3H/HeN mice.
abstract: Rickettsia rickettsii is the etiological agent of Rocky Mountain spotted fever (RMSF). YbgF and TolC are outer membrane-associated proteins of R. rickettsii that play important roles in its interaction with host cells. We investigated the immunogenicity of YbgF and TolC for protection against RMSF. We immunized C3H/HeN mice with recombinant R. rickettsii YbgF (rYbgF) or TolC (rTolC). Rickettsial burden and impairment in the lungs, spleens, and livers of rYbgF-immunized mice were significantly lower than in rTolC-immunized mice. The ratio of IgG2a to IgG1 in rYbgF-immunized mice continued to increase over the course of our experiments, while that in rTolC-immunized mice was reduced. The proliferation and cytokine secretion of CD4(+) and CD8(+) T cells isolated from R. rickettsii-infected mice were analyzed following antigen stimulation. The results indicated that proliferation and interferon (IFN)-γ secretion of CD4(+) or CD8(+) T cells in R. rickettsii-infected mice were significantly greater than in uninfected mice after stimulation with rYbgF. YbgF is a novel protective antigen of R. rickettsii. Protection conferred by YbgF is dependent upon IFN-γ-producing CD4(+) and CD8(+) T cells and IgG2a, which act in synergy to control R. rickettsii infection.
authors.affiliation: a State Key Laboratory of Pathogen and Biosecurity; Beijing Institute of Microbiology and Epidemiology ; Fengtai , Beijing , China.
authors.forename: Wenping
authors.initials: W
authors.lastname: Gong
authors.forename: Yong
authors.initials: Y
authors.lastname: Qi
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Xiong
authors.forename: Jun
authors.initials: J
authors.lastname: Jiao
authors.forename: Changsong
authors.initials: C
authors.lastname: Duan
authors.forename: Bohai
authors.initials: B
authors.lastname: Wen
mesh_terms: D000825:Animal Structures / Q000382:microbiology / Q000473:pathology; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D058491:Bacterial Load; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology* / Q000302:isolation & purification; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D008809:Mice, Inbred C3H; D012284:Rickettsia rickettsii / Q000276:immunology* / Q000302:isolation & purification; D012373:Rocky Mountain Spotted Fever / Q000276:immunology / Q000517:prevention & control*
chemical_list: D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001428:Bacterial Vaccines; D016207:Cytokines
keywords: Rickettsia rickettsii; Rocky Mountain spotted fever; YbgF; cell-mediated immune response; protective antigen