Evaluation of recombinant Omp31 subcellular vaccine against Brucella ovis in rams

ESTEIN S.M., CHEVES P. C., FIORENTINO M.A., CASSATARO J., PAOLICCHI, F.A., BOWDEN, R.A.

Colonia del Sacramento. Uruguay.

Simposio; Simposium of Reproduction in Small Ruminants 2004; 2004

Evaluation of recombinant Omp31 subcellular vaccine against B. ovis in rams Silvia M. Esteina*, Pablo Ch. Chevesb, María A. Fiorentinob,, Juliana Cassataroc, Fernando. A. Paolicchib, Raúl A. Bowdena a) Laboratorio de Inmunoquímica y Biotecnología, Facultad de Ciencias Veterinarias, U.N.C.P.B.A, Tandil (7000), Argentina. Telephone/fax: +54 2293 42 2357 (silmares@vet.unicen.edu.ar) *CIC, Buenos Aires, Argentina b) Laboratorio de Bacteriología, Departamento de Producción Animal, INTA, Balcarce (7620), Argentina.  CONICET, Buenos Aires, Argentina. c) Laboratorio de Inmunogenética, Hospital de Clínicas ?José de San Martín?, Facultad de Medicina. UBA, Buenos Aires. Argentina. Brucella ovis causes an infectious disease in sheep characterized by epididymitis and infertility in rams and abortion in ewes. Control measures in flocks include culling of animals positive to serological tests and/or bacteriological culture. Vaccination programs are the only viable means for the control of B. ovis in countries with a high incidence. B. melitensis. Rev1, a smooth attenuated strain, is considered the best vaccine for the prophylaxis of ovine brucellosis. However, Rev1 induces abortions, lead to persistent immune response which could interfere with serological diagnostic tests and this strain is virulent for humans. Accordingly, research is under way to develop subcellular vaccines avoiding the disadvantages of Rev1. Brucella surface molecules are good candidates for such vaccines. A hot saline extract from B.ovis, mainly composed of rough lipopolysaccharide (R-LPS) and major outer membrane proteins (OMPs), has been shown to protect rams against B.ovis. Major OMPs, which includes Omp25 and Omp31 from B. melitensis, has been produced in Escherichia coli. In our study, we evaluated in rams the: a) immunogenicity of detergent-extracted recombinant Omp31 from B. melitensis; b) protective activity of this immunogen against B. ovis. Immunizations were performed in three occasions. Rams were challenged with B. ovis obtained from naturally infected ram. Blood samples were taken for serological studies and rams were examined for genital lesions. Animals were slaughtered and were subjected to bacteriological and histological examinations. Antibody response was evaluated in serum by ELISA and cellular immune response was measured in vivo after intradermal injection of purified rOmp31. Inmunization induced IgG specific antibodies in serum able to bind whole B. ovis cells. Immunized rams showed skin reactivity to rOmp31. These results showed that Omp31 induces antibody and cellular mechanisms in sheep and that is a potential component for a subcellular vaccine against B. ovis.