Submitted to: International Journal for Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/28/2006
Publication Date: 6/6/2006
Citation: Su, C., Zhang, X., Dubey, J.P. 2006. Genotyping of toxoplasma gondii by multifocus PCR-RFLP markers: a high resolution and simple method for identification of parasites. International Journal for Parasitology. 36:841-848. Interpretive Summary: Toxoplasma gondii is a single-celled parasite of all warm-blooded hosts worldwide. It causes mental retardation and loss of vision in children, and abortion in livestock. Cats are the main reservoir of T. gondii because they are the only hosts that can excrete the resistant stage (oocyst) of the parasite in the feces. Humans become infected by eating undercooked meat from infected animals and food and water contaminated with oocysts.Scientists at the USDA Agricultural Research Service and a University of Tennessee , Knoxville new genetic markers for Toxoplasma.. The results will be of interest to biologists, parasitologists, and veterinarians.
Technical Abstract: It was generally believed that Toxoplasma gondii had a clonal population structure with three predominant lineages namely type I, II and III. This was largely based on genotyping of more than a hundred T. gondii isolates originated from a variety of human and animal sources in north America and Europe. Recent genotyping studies on T. gondii strains from wild animals or human patients from different geographical regions revealed the high frequency of non-archetypal genotypes, suggesting the overall diversity of T. gondii population might be much higher than we thought. However, as most genotyping studies had relied on a few biallelic markers, the resolution and discriminative power of identifying parasite isolates were quite low. To date, there is no commonly used set of markers to genotype T.gondii strains, and it is not feasible to compare results from different laboratories. Here, we developed nine PCR-RFLP markers with each of them capable of distinguishing the three archetypal T. gondii lineages in one restriction-enzyme reaction by agarose gel electrophoresis. Genotyping 46 T. gondii isolates from different sources using these markers showed that they could readily distinguish the archetypal from atypical types and to reveal genetic diversity of the parasites. In addition, mixed strains in samples could be easily detected by these markers. Use of these markers will facilitate the identification of T. gondii isolates in epidemiological and population genetic studies.