ARS | Publication request: ISOLATE DESIGNATION AND CHARACTERIZATION OF TOXOPLASMA GONDII ISOLATES FROM PIGS IN THE UNITED STATES

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 4, 2008
Publication Date: February 10, 2009
Citation: Velmurugan, G., Dubey, J.P., Su, C. 2009. Isolate designation and characterization of Toxoplasma gondii isolates from pigs in the United States. Journal of Parasitology. 95:95-99.

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 Beltsville Agricultural Research Center and University of Tennessee report genetic diversity of Toxoplasma in pigs USA. The results will be of interest to biologists, parasitologists, and veterinarians

Technical Abstract: Pigs are considered the most important meat source of Toxoplasma gondii for humans in the USA. In the present study, 168 T. gondii isolates (designatedTgPgUs15-182) from various sources were genotyped using 10 PCR-RFLP markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico). Genotyping data from an additional 14 isolates recently collected and analyzed from pigs with toxoplasmosis in Maryland were included for analysis. Nine genotypes (#1-9) were recognized from the collection of a total 182 T. gondii isolates. Most isolates (56%,102 of 182) were clonal Type II (genotypes #1 and #2) and 27% (49 of 182) were clonal Type III (genotype #3) strains. Genotype #4 had Type II alleles, except Type I allele at loci Apico and L358. Eight isolates (genotype #5) had a combination of alleles I, II, and III at different loci, and all 8 isolates were from sows in Iowa. The remaining 6 isolates were divided into genotypes # 6-9 and had a combination of different alleles. Eight of the 9 genotypes were previously reported in different animal species and geographical regions. In conclusion, along with the predominance of clonal Type II and III strains, a few diverse T. gondii lineages are also circulating in domestic pigs used for human consumption .