BABESIA-CANIS - EVIDENCE FOR GENETIC DIVERSITY AMONG ISOLATES REVEALED BY RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS

The genetic diversity of B. canis was investigated by restriction frag ment length polymorphism analysis. For this purpose, we identified a B abesia canis specific DNA probe named pS8. This 1.2 kbp probe can dete ct as low as 20 pg of B. canis DNA. Results suggest that the pS8 probe is distributed in multiple copies throughout the genome though is pro bably not itself internally repetitious, i.e. not structured into bloc ks of tandem units. This probe reveals discrete hybridizing fragments in B. canis enzyme-digested genomic DNA. RFLP patterns obtained with t he pS8 probe revealed a large genetic diversity between various isolat es and led us to distinguish several clones derived from a single isol ate. Results suggest that for a single isolate, the fingerprints obtai ned reflect those of a few quantitatively dominant clones. This techni que can now be routinely applied and provides a convenient tool for th e characterization and the identification of B. canis isolates, strain s and clones.