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United States Department of Agriculture

Agricultural Research Service

Title: Variations in Microsatellite Sequences Provide Evidence for Population Differences and Multiple Ribosomal Gene Repeats Within Trichinella Pseudospiralis

item Zarlenga, Dante
item Aschenbrenner, Richard
item Lichtenfels, James

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 28, 1995
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 suggesting 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 reserachers in determing whether certain populations of this species are more infectious to humans than others.

Technical Abstract: Enzymatic amplification of expansion segment 5 sequences within domain IV of the large subunit ribosomal RNA generated distinct results among geographical isolates of Trichinella pseudospiralis from Russia, North America and Australia from both avian and mammalian hosts. Discrete, multiple DNA fragments ranging in approximate size from 285 to 315 bp were observed within and among each of the isolates tested. Polymerase chain reaction performed on individual adult parasites from the Russian isolate resulted in multiple DNA fragments that were comparable to those generated from pooled genomic DNA. Sequence analysis of amplified fragments demonstrated that fragment length variation resulted primarily from the dinucleotide (GT)n and trinucleotide (TGC)n microsatellite repeats present within the expansion differences within the species as well as multiple large subunit ribosomal genes present within individual parasites.

Last Modified: 4/18/2015
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