Korean J Parasitol.  2007 Mar;45(1):1-9. 10.3347/kjp.2007.45.1.1.

Molecular characterization of bacterial endosymbionts of Acanthamoeba isolates from infected corneas of Korean patients

• Xuan YH
• Yu HS
• Jeong HJ
• Seol SY
• Chung DI
• Kong HH

• KMID: 1088627
• DOI: http://doi.org/10.3347/kjp.2007.45.1.1

Abstract

The endosymbionts of 4 strains of Acanthamoeba (KA/E9, KA/E21, KA/E22, and KA/E23) isolated from the infected corneas of Korean patients were characterized via orcein stain, transmission electron microscopic examination, and 16S rDNA sequence analysis. Double membrane-bound, rod-shaped endosymbionts were distributed randomly throughout both the trophozoites and cysts of each of Acanthamoeba isolates. The endosymbionts of KA/E9, KA/E22, and KA/E23 were surrounded by electron-translucent areas. No lacunae-like structures were observed in the endosymbionts of KA/E21, the bacterial cell walls of which were studded with host ribosomes. Comparative analyses of the 16S rDNA sequences showed that the endosymbionts of KA/E9, KA/E22 and KA/E23 were closely related to Caedibacter caryophilus, whereas the KA/E21 endosymbiont was assigned to the Cytophaga-Flavobacterium-Bacteroides (CFB) phylum. In the 4 strains of Acanthamoeba, the hosts of the endosymbionts were identified as belonging to the Acanthamoeba castellanii complex, which corresponds to the T4 genotype. Acanthamoeba KA/E21 evidenced characteristics almost identical to those of KA/E6, with the exception of the existence of endosymbionts. The discovery of these endosymbionts from Acanthamoeba may prove essential to future studies focusing on interactions between the endosymbionts and the amoebic hosts.

Keyword

Acanthamoeba; bacterial endosymbiont; keratitis; 16S rDNA; 18S rDNA

MeSH Terms

Acanthamoeba/genetics/isolation & purification/*microbiology
Acanthamoeba Keratitis/*microbiology/*parasitology
Animals
Bacteria/*genetics/isolation & purification
Base Sequence
Cornea/microbiology/*parasitology
DNA, Mitochondrial/genetics
Humans
Korea
Microscopy, Electron, Transmission/methods
Oxazines/metabolism
Phylogeny
RNA, Ribosomal, 16S/genetics
RNA, Ribosomal, 18S/genetics
Symbiosis