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A simple random amplified polymorphic DNA genotyping method for field isolates of Dermatophilus congolensis
J Larrasa1, A Garcia, N C Ambrose
1Cátedra de Patologia Infecciosa, Universidad de Extremadura, Facultad de Veterinaria, Cáceres, Spain.
Summary
Genotyping Dermatophilus congolensis, a pathogen causing various animal diseases, was improved with new DNA extraction and Random Amplified Polymorphic DNA (RAPD) methods. Genotypic variations in D. congolensis isolates correlate with their host species, not location.
Area of Science:
- Veterinary Microbiology
- Bacterial Genetics
- Molecular Diagnostics
Background:
- Dermatophilus congolensis causes significant animal diseases like dermatophilosis, lumpy wool, and rain scald.
- Previous studies noted phenotypic variation in D. congolensis isolates, but the genetic basis remained uninvestigated.
- Standard DNA extraction methods are often ineffective for D. congolensis due to its complex, encapsulated life cycle.
Purpose of the Study:
- To develop rapid and reliable DNA extraction and Random Amplified Polymorphic DNA (RAPD) methods for genotyping D. congolensis.
- To investigate the genetic basis and extent of genotypic variation among D. congolensis isolates.
- To determine if genotypic variation correlates with host species or geographical location.
Main Methods:
- Comparison of various DNA extraction techniques and RAPD protocols.
- Optimization of DNA extraction using lysozyme, SDS, and proteinase K treatments with phenolic extraction for high-quality DNA.
- Development of a rapid, non-phenolic DNA extraction method using proteinase K and thermal shock for routine RAPD typing.
- Application of optimized methods to 38 D. congolensis field isolates and reference strains.
Main Results:
- A robust DNA extraction method yielding high-quality DNA was established.
- Optimized RAPD-PCR protocols using two random primers provided reproducible banding patterns across different DNA batches and thermal cyclers.
- Genotypic profiles of D. congolensis isolates, determined by RAPD-PCR, showed a clear correlation with the host species (cattle, sheep, horses).
- No correlation was found between the genotypic variation of isolates and their geographical origin.
Conclusions:
- The developed rapid DNA extraction and RAPD-PCR methods are effective for genotyping D. congolensis.
- Genotypic variation in D. congolensis is linked to host specificity, suggesting host-associated adaptation.
- These genotyping tools can aid in understanding the epidemiology and population structure of D. congolensis.