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Genetic analysis of Histoplasma capsulatum strains isolated from clinical specimens in thailand by a PCR-based random
1Department of Medical Sciences, National Institute of Health, Nonthaburi, Thailand.
Abstract:
Thirteen strains of Histoplasma capsulatum were isolated from clinical specimens, including those from AIDS patients, in Thailand. Random amplified polymorphic DNA (RAPD) analysis with three different PCR primers showed that the DNA fingerprint patterns of the Thai isolates were very similar to each other and homogeneous, with only one exceptional strain, although the patterns were clearly different from those of a reference North American strain with all primers tested. Although the difference in the DNA fingerprinting patterns was minor, Thai isolates could be classified into two to four groups. A common PCR band (about 700 bp) in the patterns of all H. capsulatum strains was extracted, and its DNA sequence was determined. A new PCR primer set for the identification of H. capsulatum species was developed based on this sequence information. This primer set was 100% successful in the identification of the reference strain as well as all Thai isolates. The results of specificity tests of the primer set for the identification of the fungus are also discussed.
Insights
Researchers identified unique DNA fingerprints for Histoplasma capsulatum strains in Thailand using random amplified polymorphic DNA (RAPD) analysis. A new primer set was developed for accurate species identification, showing high success rates.
Area of Science:
- Medical Mycology
- Molecular Biology
- Infectious Diseases
Background:
- Histoplasma capsulatum is an important fungal pathogen.
- Clinical isolates from Thailand, including from AIDS patients, were studied.
- Understanding geographic variations in fungal strains is crucial for diagnostics.
Purpose of the Study:
- To genetically characterize Histoplasma capsulatum strains from Thailand.
- To compare Thai isolates with a North American reference strain.
- To develop a novel PCR-based method for H. capsulatum identification.
Main Methods:
- Random amplified polymorphic DNA (RAPD) analysis using three PCR primers.
- DNA sequencing of a common PCR band.
- Development and testing of a new species-specific PCR primer set.
Main Results:
- Thai H. capsulatum isolates showed homogeneous DNA fingerprint patterns, distinct from the North American strain.
- Minor variations allowed classification of Thai isolates into 2-4 groups.
- The newly developed primer set achieved 100% success in identifying all tested H. capsulatum strains.
Conclusions:
- Thai Histoplasma capsulatum strains exhibit genetic homogeneity but differ from North American counterparts.
- A novel, highly specific PCR primer set was successfully developed for H. capsulatum identification.
- This molecular tool can aid in the accurate diagnosis of histoplasmosis in endemic regions.
