Genetic characterization of Toxoplasma gondii isolates from pigs in China

Toxoplasma gondii genetic diversity varies in different geographical regions. In South America, T. gondii isolates are highly diverse, whereas in North America and Europe, the parasite is highly clonal, with 3 distinct lineage types (I, II, III). However, little is known of the T. gondii genotypes in the People's Republic of China. Because pork is considered the principal meat source for T. gondii infection in China, we conducted a survey to determine the prevalence and genetic diversity of this parasite in pigs from central China. In total, 434 DNA samples were extracted from the hilar lymph nodes of sick pigs in Hubei and Henan provinces in central China, and 34 were T. gondii B1 gene-positive. These T. gondii -positive DNA samples were typed at 10 genetic markers, including 9 nuclear loci, i.e., SAG1, SAG2, SAG3, BTUB, GRA6, L358, PK1, c22-8, c29-2, and an apicoplast locus Apico. Of these, 16 isolates could be genotyped with complete data for all loci. Two genotypes were present; one was the clonal type I lineage and the other was previously identified as a widespread lineage from many hosts in China. These results indicate that these 2 genotypes may be the major lineages in China. This is the first report of genetic typing of T. gondii isolates from pigs in central China. The results have implications for the prevention and control of T. gondii infections in humans and other animals.