Genetic Characterization of Clinical Acanthamoeba Isolates from Japan using Nuclear and Mitochondrial Small Subunit Ribosomal RNA

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Journal Title, Volume, Page: 
Korean J Parasitol 2013; 51: 401-411
Year of Publication: 
Hussein AIA,
Current Affiliation: 
Faculty of Medicine & Health Sciences, Department of Biomedical Sciences, An-Najah National University, Nablus, Palestine
Rahman MM,
Yagita K,
Kobayashi A,
Oikawa Y,
Matsumura T,
Tokoro M
Preferred Abstract (Original): 

Abstract: Because of an increased number of Acanthamoeba keratitis (AK) along with  ssociated disease burdens, medical professionals have become more aware of this pathogen  in recent years. In this study, by analyzing both the nuclear 18S small subunit ribosomal  NA (18S rRNA) and mitochondrial 16S rRNA gene loci, 27 clinical Acanthamoeba strains  that caused AK in Japan were classified into 3 genotypes, T3 (3 strains), T4 (23 strains) and  T5 (one strain). Most haplotypes were identical to the reference haplotypes reported from all over the world, and thus no specificity of the haplotype distribution in Japan was found. The  T4 sub-genotype analysis using the 16S rRNA gene locus also revealed a clear sub- conformation within the T4 cluster, and lead to the recognition of a new sub-genotype T4i,  addition to the previously reported sub-genotypes T4a–T4h. Furthermore, the 9 out of 23  strains in the T4 genotype were identified to a specific haplotype (AF479533), which seems  to be a causal haplotype of AK. While the heterozygous nuclear haplotypes were observed  from the 2 strains, the mitochondrial haplotypes were homozygous as T4 genotype in the  both strains, and suggested that the possibility of nuclear hybridization (mating reproduction) between different strains in Acanthamoeba. The nuclear 18S rRNA gene and mitochondrial 16S rRNA gene loci of Acanthamoeba spp. possess different unique characteristics usable for  the genotyping analyses, and those specific features could contribute to the establishment of  olecular taxonomy for the species complex of Acanthamoeba. 

 Key words: Acanthamoeba, keratitis, mixed sequence profile, 18S rRNA, 16S rRNA