Molecular phylogeny of acanthamoeba

Area of Science:

• Microbiology
• Molecular Biology
• Parasitology

Background:

• The Acanthamoeba genus has been historically classified using morphological characteristics, which are prone to variability.
• Previous phylogenetic studies using isoenzyme and mitochondrial DNA restriction fragment length polymorphism (Mt DNA RFLP) showed limitations in species identification, proving more useful for strain discrimination.
• The need for stable phylogenetic markers has driven research into molecular methods for Acanthamoeba classification.

Purpose of the Study:

• To investigate the phylogenetic identification of Acanthamoeba isolates from the Republic of Korea using molecular methods.
• To determine the predominant genotypes of Acanthamoeba in both clinical and environmental samples.
• To assess the potential pathogenicity of environmental Acanthamoeba isolates based on their genetic similarity to clinical strains.

Main Methods:

• Sequence analysis of 18s ribosomal RNA coding DNA (18s rDNA) was employed for phylogenetic analysis.
• Restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA (Mt DNA RFLP) was also utilized.
• Comparison of sequence types and RFLP patterns between clinical and environmental isolates.

Main Results:

• Phylogenetic analysis based on 18s rDNA distinguished three morphological groups and identified 12 unique sequence types (genotypes T1-T12).
• The majority of both clinical and environmental Acanthamoeba isolates from Korea belonged to genotype T4.
• Environmental isolates from contact lens cases, tap water, and ocean sediments exhibited similar Mt DNA RFLP patterns to clinical isolates.

Conclusions:

• Sequence analysis of 18s rDNA provides a robust method for Acanthamoeba phylogeny, confirming morphological groupings and defining genotypes.
• The prevalence of genotype T4 in Korean clinical and environmental isolates highlights its significance.
• The genetic similarity between environmental and clinical isolates suggests that environmental Acanthamoeba strains may pose a risk for causing keratitis.