Summary auto-generated
Researchers used bacterial restriction-endonuclease DNA analysis (BRENDA) to differentiate strains of Leptospira interrogans, a pathogenic bacterium identified traditionally by serological methods. They examined field isolates and reference strains of multiple serovars from various global sources. Field strains of serovar hardjo from New Zealand, Australia, and Northern Ireland showed identical DNA restriction patterns but differed markedly from the reference strain Hardjoprajitno, likely due to different ecological niches. Similarly, field isolates of balcanica and tarassovi differed from their reference strains, suggesting these serovars can be subdivided into distinct subtypes. In contrast, serovars pomona, ballum, and copenhageni showed minimal or no differences between field and reference strains. The authors concluded that BRENDA provides a more precise method than serology for identifying leptospiral strains and understanding epidemiological relationships between bacterial strains and their hosts, potentially necessitating designation of new reference strains for identified subtypes.
Key findings
- Field strains of L. interrogans serovar hardjo from multiple countries were indistinguishable from each other by BRENDA but differed significantly from the reference strain Hardjoprajitno, suggesting different ecological niches.
- Serovars balcanica and tarassovi field isolates showed striking differences from their reference strains, indicating these serovars can be subdivided into distinct subtypes using DNA restriction analysis.
- Some serovars (pomona, ballum, copenhageni) showed no or minimal differences between reference and field strains, demonstrating variable utility of BRENDA across different serovars.
- BRENDA overcomes limitations of serological methods and allows more precise epidemiological characterization of leptospiral strains and their relationships to host species.
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Abstract
Various strains of Leptospira interrogans were compared by bacterial restriction-endonuclease DNA analysis (BRENDA). Field strains of serovar hardjo isolated from domestic animals in New Zealand, Australia and Northern Ireland were indistinguishable from one another but differed strikingly from the hardjo reference strain Hardjoprajitno. Similarly, field isolates of balcanica and tarassovi differed from their serovar reference strains, probably owing to a difference in epidemiological niche. Subdivision of these serovars into distinct subtypes as defined by BRENDA is therefore useful and justified. In contrast, analysis of serovars pomona, ballum and copenhageni shows that field and reference strains were identical, or differed only by a single band. It is suggested that BRENDA will overcome many of the problems associated with serological methods of identifying serovars and allow more precise definition of epidemiological relationships between strains and their hosts.