The differentiation of a newly described Asian taeniid from Taenia saginata using enzymatically amplified non-transcribed ribosomal DNA repeat sequences.

ABSTRACT

A newly described Asian taeniid which is morphologically indistinguishable from adult Taenia saginata has been identified in the aboriginal population of Taiwan. Hybridization patterns of restriction enzyme digested genomic DNA isolated from "Taiwan" Taenia and Taenia saginata revealed distinct variations between these cestodes. We have demonstrated by Southern blot analysis of ribosomal DNA fragments that Taiwan Taenia and T. saginata differ in a 2.4 kb fragment present in Bam HI digested DNA from T. saginata but absent from Taiwan Taenia DNA. The unique 2.4 kb sequence from T. saginata, as well as a partially homologous 3.1 kb fragment found in both Taiwan Taenia and T. saginata, contain sequences shown to be complementary to the 3'-end of the large ribosomal DNA subunit and to a large portion of the non-transcribed ribosomal DNA repeat. These fragments were subcloned into pUC 13 plasmid DNA, restriction enzyme mapped and partially sequenced. Two oligonucleotides complementary to regions on both the 2.4 kb and the 3.1 kb fragments were synthesized which generate 1.0 kb and 0.29 kb fragments specific for Taiwan Taenia and T. saginata, respectively, when used as primers during enzymatic amplification of cestode genomic DNA. Using this technique, we have been able to determine the identify of either cestode from a single proglottid with less than 200 ng of genomic DNA per reaction and further demonstrate that Taiwan Taenia exists in other parts of Eastern Asia.