title: Cloning and sequencing of yajC and secD homologs of Brucella abortus and demonstration of immune responses to YajC in mice vaccinated with B. abortus RB51.
abstract: To identify Brucella antigens that are potentially involved in stimulating a protective cell-mediated immune response, a gene library of Brucella abortus 2308 was screened for the expression of antigens reacting with immunoglobulin G2a antibodies from BALB/c mice vaccinated with B. abortus RB51. One selected positive clone (clone MCB68) contained an insert of 2.6 kb; nucleotide sequence analysis of this insert revealed two open reading frames (ORFs). The deduced amino acid sequences of the first and second ORFs had significant similarities with the YajC and SecD proteins, respectively, of several bacterial species. Both the YajC and SecD proteins were expressed in Escherichia coli as fusion proteins with maltose binding protein (MBP). In Western blots, sera from mice vaccinated with B. abortus RB51 recognized YajC but not SecD. Further Western blot analysis with purified recombinant YajC protein indicated that mice inoculated with B. abortus 19 or 2308 or B. melitensis RM1 also produced antibodies to YajC. In response to in vitro stimulation with recombinant MBP-YajC fusion protein, splenocytes from mice vaccinated with B. abortus RB51 were able to proliferate and produce gamma interferon but not interleukin-4. This study demonstrates, for the first time, the involvement of YajC protein in an immune response to an infectious agent.
authors.affiliation: Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0342, USA.
authors.forename: R
authors.initials: R
authors.lastname: Vemulapalli
authors.forename: A J
authors.initials: AJ
authors.lastname: Duncan
authors.forename: S M
authors.initials: SM
authors.lastname: Boyle
authors.forename: N
authors.initials: N
authors.lastname: Sriranganathan
authors.forename: T E
authors.initials: TE
authors.lastname: Toth
authors.forename: G G
authors.initials: GG
authors.lastname: Schurig
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D001483:Base Sequence; D002003:Brucella abortus / Q000276:immunology*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005260:Female; D007371:Interferon-gamma / Q000096:biosynthesis; D026901:Membrane Transport Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000276:immunology; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013154:Spleen / Q000166:cytology / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology*; D014611:Vaccination
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; C499394:SecD protein, E coli; C116101:YajC protein, Brucella; C075767:secD protein, Bacteria; D007371:Interferon-gamma