A riboprinting scheme for identification of unknown Acanthamoeba isolates at species level.

We describe a riboprinting scheme for identification of unknown Acanthamoeba isolates at the species level. It involved the use of PCR-RFLP of small subunit ribosomal RNA gene (riboprint) of 24 reference strains by 4 kinds of restriction enzymes. Seven strains in morphological group I and III were identified at species level with their unique sizes of PCR product and riboprint type by Rsa I. Unique RFCP of 17 strains in group II by Dde I, Taq I and Hae III were classified into: (1) four taxa that were identifiable at the species level, (2) a subgroup of 4 taxa and a pair of 2 taxa that were identical with each other, and (3) a species complex of 7 taxa assigned to A. castellanii complex that were closely related. These results were consistent with those obtained by 18s rDNA sequence analysis. This approach provides an alternative to the rDNA sequencing for rapid identification of a new clinical isolate or a large number of environmental isolates of Acanthamoeba.