First Report of Genotyping of Toxoplasma gondii Isolates From Wild Birds in China

Toxoplasma gondii is an important cosmopolitan opportunistic protozoan parasite, which threatens the health of human beings and animals. Genetic characterization of isolates from South America has revealed high genetic diversity. In contrast, isolates from North America and Europe were highly clonal, with 3 major lineages known as the Types I, II, and III. However, limited information on T gondii genotypes has been reported in The People's Republic of China. Here we conducted a survey to determine genetic diversity of this parasite in wild birds of China. In total, tissues from breast muscle of 178 wild birds, including 98 common pheasants (Phasianus colchicus), 35 tree sparrows (Passer montanus), 22 house sparrows (Passer domesticus), 20 saxaul sparrows (Passer ammodendri), and I cinnamon sparrow (Passer rutilans), were tested for T gondii infection, 4 of which were found to be positive for the T. gondii B1 gene by PCR amplification. These positive DNA samples were typed at 10 genetic markers, including 9 nuclear loci, i.e., SAG1, 5'- and 3'-SAG2, alternative SAG2, SAG3, GRA6, L358, PK1, c22-8, c29-2, and an apicoplast locus Apico. Of these, 3 isolates were genotyped with complete data for all loci, and 2 genotypes (Type I and Type II variant) were identified. This is the first report of genetic typing of T. gondil isolates from wild birds from different regions in China. The results suggest that the Type I and II variant strains are circulating in wild birds in China, and these birds are potential reservoirs for T. gondii transmission.