Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 14, 1995
Publication Date: N/A
Technical Abstract: It was previously found that genetic variability among Leptospira borgpetersenii serovar hardjo type hardjobovis (H-HB) isolates correlated with geographic location, and that genetically variable isolates differed in phenotype during experimental infection. In this study, genetic variability among isolates was determined by DNA hybridization analysis of restriction endonuclease (RE) genomic digests with cloned hemolysin genes, hemolysin being a putative virulence factor. Hybridization was performed using digests of over 200 different isolates from different geographic regions. Seven distinct genetic groups were detected. A previous report has shown that sphB contains a region of 45 base pair direct repeats. Variation within this region could be responsible for observed polymorphisms. This hypothesis was investigated by designing PCR primers to amplify a region from genomic DNA including this segment of repeats. Differences in PCR product size were consistent with differences observed by aforementioned hybridization. RE digestion of PCR products confirmed that polymorphisms are located within the repeat and are likely due to differences in the number of repeats present in different sphB alleles. Additionally, one group of isolates may possess a different sized repeating unit. These polymorphisms may affect sphB expression which in turn may play a role in the variable pathogenesis seen among different isolates of serovar H-HB.