Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/14/1995
Publication Date: N/A
Technical Abstract: Genetic variability exists among isolates of Leptospira borgpetersenii serovar hardjo type hardjobovis (HB), the primary cause of bovine leptospirosis. Previously, we found that genetic variability among isolates correlated with geographic location, and that genetically variable isolates differed with respect to pathogenicity and immune response in experimental bovine infections. Vaccination with one strain of serovar hardjo type HB fails to prevent infection with a second strain, despite the presence of agglutinating antibody. Therefore, it was hypothesized that protection from challenge might not be possible using a strain different from the infecting strain. Cattle were infected with serovar hardjo type HB, strain 203, and urinary shedding of leptospires was demonstrated. Cattle were treated to eliminate infection, and rechallenged with the same or one of two other hardjo strains, 197 or 356. Animals were monitored by culture and fluorescent antibody testing of urine to detect shedding. Leptospires were not detected in the urine by either method following rechallenge. In conclusion, the immune response produced by active infection appears to be effective in preventing reinfection by the same or different strains of serovar hardjo type HB. This indicates that vaccines which stimulate an immune response similar to that seen with active infection may be effective in preventing infection with serovar hardjo type HB.