title: Role in virulence of a Brucella abortus protein exhibiting lectin-like activity.
abstract: Brucella abortus is a facultative, intracellular zoonotic pathogen which can cause undulant fever in humans and abortions in cattle. A 14-kDa protein of B. abortus was previously identified to be immunogenic in animals infected with Brucella spp. In this study, we discovered that the 14-kDa protein possessed immunoglobulin binding and hemagglutination properties that appeared to be based on the protein's lectin-like properties. Hemagglutination inhibition experiments suggested that the 14-kDa protein has affinity towards mannose. Disruption of the gene encoding the 14-kDa protein in virulent B. abortus strain 2308 induced a rough-like phenotype with an altered smooth lipopolysaccharide (LPS) immunoblot profile and a significant reduction in the bacterium's ability to replicate in mouse spleens. However, the mutant strain was stably maintained in mouse spleens at 2.0 to 2.6 log(10) CFU/spleen from day 1 to week 6 after intraperitoneal inoculation with 4.65 log(10) CFU. In contrast to the case for the smooth virulent strain 2308, in the rough attenuated strain RB51 disruption of the 14-kDa protein's gene had no effect on the mouse clearance pattern. These findings indicate that the 14-kDa protein of B. abortus possesses lectin-like properties and is essential for the virulence of the species, probably because of its direct or indirect role in the synthesis of smooth LPS.
authors.affiliation: Center for Molecular Medicine and Infectious Diseases, 1410 Prices Fork Road, Blacksburg, VA 24061, USA.
authors.forename: Tracy H
authors.initials: TH
authors.lastname: Vemulapalli
authors.forename: Ramesh
authors.initials: R
authors.lastname: Vemulapalli
authors.forename: Gerhardt G
authors.initials: GG
authors.lastname: Schurig
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Boyle
authors.forename: Nammalwar
authors.initials: N
authors.lastname: Sriranganathan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001483:Base Sequence; D002003:Brucella abortus / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000472:pathogenicity*; D002006:Brucellosis / Q000378:metabolism*; D004195:Disease Models, Animal; D004926:Escherichia coli; D037102:Lectins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009154:Mutation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014774:Virulence
chemical_list: C113736:BA14K protein, Brucella; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D037102:Lectins; D011994:Recombinant Proteins