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Genotypic, phenotypic, biochemical, physiological and pathogenicity-based categorisation of Acanthamoeba strains
Naveed Ahmed Khan1, Noor Khan Tareen
1School of Biological and Chemical Sciences, Birkbeck College, University of London, London, WC1E 7HX, England, UK. n.khan@sbc.bbk.ac.uk
Folia Parasitologica
|October 17, 2003
Summary
Two Acanthamoeba polyphaga strains show significant genetic and pathogenic differences, challenging current species classifications. These findings impact the clinical diagnosis of Acanthamoeba infections.
Area of Science:
- Microbiology
- Parasitology
- Molecular Biology
Background:
- The genus Acanthamoeba presents classification challenges due to interstrain variations.
- Ribosomal DNA (rDNA) sequence differences raise questions about the relatedness of strains within the same species.
Purpose of the Study:
- To investigate the relationship between two Acanthamoeba polyphaga isolates (CCAP 1501/3c and ATCC 30871).
- To assess morphological, biochemical, physiological, molecular, and cytotoxic differences between the strains.
Main Methods:
- Morphological analysis of endocyst arm number.
- Growth assays at 37°C and on 1M mannitol.
- Isoenzyme banding pattern analysis.
- Ribosomal DNA (rDNA) restriction fragment polymorphism analysis.
- Cytotoxicity assays on corneal epithelial cells.
Main Results:
- A. polyphaga ATCC 30871 showed 6 endocyst arms (Group 2), while CCAP 1501/3c had 5 (Group 3).
- ATCC 30871 grew at 37°C and on mannitol; CCAP 1501/3c did not.
- Distinct isoenzyme and rDNA restriction patterns were observed.
- ATCC 30871 demonstrated cytotoxicity to corneal cells; CCAP 1501/3c did not.
Conclusions:
- Significant differences between the two A. polyphaga strains support reclassification.
- Findings highlight the importance of strain variability in Acanthamoeba.
- Results have implications for the clinical diagnosis of pathogenic Acanthamoeba.