Fingerprints by pulsed-field gel electrophoresis of leptospires isolated from field rats and comparison with reference Leptospira serovars

Abstract

Background: More than 260 leptospiral serovars by serology have been recorded. New genotypic methods have classified Leptospira into 20 species. Serovar identification is essential for epidemiological study of this disease. Objective: We identified fingerprints from reference serovar strains of Leptospira spp. and representative serovars from field rat isolates by pulsed-field gel electrophoresis (PFGE). Methods: Extract genomic DNA from 28 reference serovars of Leptospira spp. and 13 leptospiral isolates from field rats, selected as representative serovars Pyrogenes, Bataviae, Autumnalis, and Australis, using PFGE following NotI restriction digest. Results: PFGE with NotI restriction enzyme successfully differentiated 28 reference serovars into 27 fingerprint patterns, with the exception of serovars Copenhageni and Icterohaemorrhagiae. The discriminatory power of these reference strains was 0.99. Isolates that yielded patterns identical to their corresponding serovars were serovars Pyrogenes strain Salinem and Bataviae. Patterns for isolates of serovars Autumnalis and Australis were different from reference serovar Autumnalis strain Akiyami A and serovar Australis strain Ballico used in this study. Conclusion: PFGE can be useful for identifying serovars of leptospiral isolates from reservoirs and for identifying new serovars of Leptospira for epidemiological study. Keywords: Leptospira, leptospiral serovar, molecular typing, PFGE, pulsed-field gel electrophoresis