Genetic diversity of Acanthamoeba isolated from ocean sediments

Abstract

Genetic diversity of 18 Acanthamoeba isolates from ocean sediments was evaluated by comparing mitochondrial (mt) DNA RFLP, 18S rDNA sequences and by examining their cytopathic effects on human corneal epithelial cells versus reference strains. All isolates belonged to morphologic group II. Total of 16 restriction phenotypes of mtDNA from 18 isolates demonstrated the genetic diversity of Acanthamoeba in ocean sediments. Phylogenetic analysis using 18s rDNA sequences revealed that the 18 isolates were distinct from morphological groups I and III. Fifteen isolates showed close relatedness with 17 clinical isolates and A. castellanii Castellani and formed a lineage equivalent to T4 genotype of Byers group. Two reference strains from ocean sediment, A. hatchetti BH-2 and A. griffini S-7 clustered unequivocally with these 15 isolates. Diversity among isolates was also evident from their cytopathic effects on human corneal cells. This is the first time describing Acanthamoeba diversity in ocean sediments in Korea.

Fig. 1

Agarose gel electrophoretic restriction fragment patterns of mitochondrial DNA from 18 strains of Acanthamoeba. Lane: 1, KA/MSS1; 2, KA/MSS2; 3, KA/MSS6; 4, KA/MSS7; 5, KA/MSS8-1; 6, KA/MSS8-2; 7, KA/MSG1; 8, KA/MSG3; 9, KA/MSG4; 10, KA/MSG10; 11, KA/MSG12; 12, KA/MSG15; 13, KA/MSG16; 14, KA/MSG18; 15, KA/MSG23; 16, KA/MSG26; 17, KA/MSG27; 18, KA/MSG29. M, Hind III digested λ phage DNA as a DNA size standard.

Fig. 2

Dendrogram of 41 strains of Acanthamoeba using the UPGMA method using Phylip ver. 3.5 based on genetic divergence estimates.

Fig. 3

Cytopathic effect of 18 isolated Acanthamoeba trophozoites on human corneal epithelial cells. A, KA/MSG1; B, KA/MSG3; C, KA/MSG4; D, KA/MSG10; E, KA/MSG12; F, KA/MSG15; G, KA/MSG16; H, KA/MSG18; I, KA/MSG23; J, KA/MSG26; K, KA/MSG29; L, KA/MSS1; M, KA/MSS2; N, KA/MSS6; O, KA/MSS7; Q, KA/MSS8-1; R, KA/MSS8-2; S, control. The control was cultured without Acanthamoeba trophozoites.