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United States Department of Agriculture

Agricultural Research Service

Title: Genetic Differences among Populations of Trichinella Pseudospiralis Exhibited by Polymorphism Within Ribosomal DNA Simple Sequence Repeats

item Zarlenga, Dante
item Aschenbrenner, R
item Lichtenfels, James

Submitted to: Trichinellosis International Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 10, 1996
Publication Date: N/A

Interpretive Summary: Speciation within the genus Trichinella remains a controversial issue, notwithstanding the problems associated with population differences and host specificity among the genotypes. Recent reports of outbreaks implicating the avian species, T. pseudospiralis, as a pathogen in humans has prompted research on population differences and host specificities within this species. Herein, we have developed a simple and rapid PCR based method to distinguish differences among populations of this species of Trichinella and have demonstrated that intraspecific genetic variations do occur in what otherwise have been considered highly conserved genes. This finding will assist researchers in determining whether certain populations of this species are more infectious to humans than others.

Technical Abstract: Difference among populations as well as the presence of multiple alleles of the large subunit ribosomal DNA were demonstrated within the species T. pseudospiralis. Polymerase chain reaction performed on lsrDNA sequences generated distinct banding patterns among geographical isolates of T. pseudospiralis from Russia, North America, and Australia. Enzymatic amplification of individual adult parasites from each isolate resulted in multiple DNA fragments ranging in approximate size from 285 to 360 bp and were comparable to those generated from pooled genomic DNA. Sequence analysis of amplified fragments demonstrated that fragment length variation resulted primarily from the dinucleotide (TG)n and trinucleotide (TGC)n microsatellite repeats present within this region of the rDNA. Results are consistent with these isolates being geographically separated for a substantial number of generations to permit independent sequence changes both within and outside the microsatellite regions.

Last Modified: 4/22/2015
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