title: Immunization with Brucella VirB proteins reduces organ colonization in mice through a Th1-type immune response and elicits a similar immune response in dogs.
abstract: VirB proteins from Brucella spp. constitute the type IV secretion system, a key virulence factor mediating the intracellular survival of these bacteria. Here, we assessed whether a Th1-type immune response against VirB proteins may protect mice from Brucella infection and whether this response can be induced in the dog, a natural host for Brucella. Splenocytes from mice immunized with VirB7 or VirB9 responded to their respective antigens with significant and specific production of gamma interferon (IFN-γ), whereas interleukin-4 (IL-4) was not detected. Thirty days after an intraperitoneal challenge with live Brucella abortus, the spleen load of bacteria was almost 1 log lower in mice immunized with VirB proteins than in unvaccinated animals. As colonization reduction seemed to correlate with a Th1-type immune response against VirB proteins, we decided to assess whether such a response could be elicited in the dog. Peripheral blood mononuclear cells (PBMCs) from dogs immunized with VirB proteins (three subcutaneous doses in QuilA adjuvant) produced significantly higher levels of IFN-γ than cells from control animals upon in vitro stimulation with VirB proteins. A skin test to assess specific delayed-type hypersensitivity was positive in 4 out of 5 dogs immunized with either VirB7 or VirB9. As both proteins are predicted to locate in the outer membrane of Brucella organisms, the ability of anti-VirB antibodies to mediate complement-dependent bacteriolysis of B. canis was assessed in vitro. Sera from dogs immunized with either VirB7 or VirB9, but not from those receiving phosphate-buffered saline (PBS), produced significant bacteriolysis. These results suggest that VirB-specific responses that reduce organ colonization by Brucella in mice can be also elicited in dogs.
authors.affiliation: Instituto de Estudios de la Inmunidad Humoral (IDEHU, CONICET-UBA), Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Cora N
authors.initials: CN
authors.lastname: Pollak
authors.affiliation: Servicio de Teriogenología, Facultad de Ciencias Veterinarias, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: María Magdalena
authors.initials: MM
authors.lastname: Wanke
authors.affiliation: Laboratorio de Inmunología, Departamento de Sanidad Animal y Medicina Preventiva, Centro de Investigación Veterinaria de Tandil (CIVETAN, CONICET), Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires, Tandil, Argentina.
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Estein
authors.affiliation: Instituto de Estudios de la Inmunidad Humoral (IDEHU, CONICET-UBA), Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: M Victoria
authors.initials: MV
authors.lastname: Delpino
authors.affiliation: Servicio de Teriogenología, Facultad de Ciencias Veterinarias, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Norma E
authors.initials: NE
authors.lastname: Monachesi
authors.affiliation: Servicio de Teriogenología, Facultad de Ciencias Veterinarias, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Elida A
authors.initials: EA
authors.lastname: Comercio
authors.affiliation: Instituto de Estudios de la Inmunidad Humoral (IDEHU, CONICET-UBA), Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Fossati
authors.affiliation: Instituto de Estudios de la Inmunidad Humoral (IDEHU, CONICET-UBA), Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina pablobal@ffyb.uba.ar.
authors.forename: Pablo C
authors.initials: PC
authors.lastname: Baldi
mesh_terms: D000276:Adjuvants, Immunologic; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D058491:Bacterial Load; D001426:Bacterial Proteins / Q000008:administration & dosage / Q000276:immunology*; D058947:Bacterial Secretion Systems; D001433:Bacteriolysis; D002002:Brucella / Q000254:growth & development* / Q000276:immunology* / Q000472:pathogenicity; D002004:Brucella Vaccine / Q000008:administration & dosage / Q000276:immunology*; D002003:Brucella abortus / Q000276:immunology; D041002:Brucella canis / Q000276:immunology; D004285:Dogs; D006968:Hypersensitivity, Delayed; D007279:Injections, Subcutaneous; D007371:Interferon-gamma / Q000276:immunology; D015847:Interleukin-4 / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000382:microbiology*; D018417:Th1 Cells / Q000276:immunology*; D014611:Vaccination
chemical_list: D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D002004:Brucella Vaccine; D011994:Recombinant Proteins; D015847:Interleukin-4; D007371:Interferon-gamma