[Leptospira interrogans serovar Pomona: detection of antigenic differences among 3 regional isolates from cattle and...

Leptospirosis is a zoonosis caused by Leptospira interrogans. This disease is diagnosed by quantification of specific immunoglobulins in serum by the microagglutination test (MAT). The aims of this research were: a) to compare the protein profiles of 3 clinical isolates of bovine leptospirosis with the reference strain used for the MAT, and b) to identify the immunodomain antigens of the regional isolates through PAGE and immunoblotting techniques of bovine sera from infected, vaccinated and MAT-negative animals. Coomassie-blue stained gels revealed extensive protein similarities between pathogenic and reference strain. Most infected (8/10) and vaccinated animal sera (4/7) showed by immunoblotting a similar reactivity against the proteins from pathogenic leptospires, with a strong band of 25-30 kDa which was not detected in the reference strain. The lack of correlation between MAT and immunoblotting techniques for infected animals could be due either to the infection stage at which the diagnosis was made or to the immunoglobulin isotype involved in the response. Results obtained would confirm the antigenic differences between the 3 isolates and the reference strain.