Infection status and genotype identification of Toxoplasma gondii in pigs in Jinzhong City,Shanxi Province
Objective To understand the genotype characteristics of Toxoplasma gondii in Jinzhong City,Shanxi Province,and provide a basis for the prevention and control of toxoplasmosis in pigs.Methods In 2021,pig lymphatic and muscle tissues were collected from Taigu District,Pingyao County,and Xiyang County in Jinzhong City,Shanxi Province.The genomic DNA of the samples was extracted using an animal tissue extraction kit,and the Bl gene of T.gondii was amplified and sequenced using semi-nested PCR.Using the polymerase chain reaction re-striction fragment length polymorphism(PCR-RFLP)method,12 loci including SAG1,5'-SAG2,3'-SAG2,alter.SAG2,SAG3,BTUB,GRA6,c22-8,c29-2,L358,PK1,and Apico were amplified from positive samples and 8 reference strains of T.gondii.The amplified fragments were digested using restriction endonucleases,and the digested products were compared with 8 international reference strains of T.gondii.Genotypes were determined by band size.Results A total of 37 positive samples of T.gondii were detected in 130 pigs in Jinzhong City,Shanxi Province,with a posi-tive rate of 28.5%(37/130).Among them,the positive rate in Taigu District is 32.7%(18/55),Pingyao County is 26.0%(13/50),and Xiyang County is 24.0%(6/25).The positive rate of T.gondii in pig lymphoid tissue is 33.0%(33/100),and the positive rate of T.gondii in muscle tissue is 13.3%(4/30).Out of 37 positive tissues for T.gondii,one sample was successfully amplified and all loci were cleaved,identified as ToxoDB#9;One sample successfully amplified and cleaved 8 sites,suspected to be ToxoDB#9,ToxoDB#20,or ToxoDB#137;Three samples were successfully amplified and enzyme cleaved to 6 sites,suspected to be ToxoDB#9,ToxoDB#20,or ToxoDB#137;One sample successfully ampli-fied and cleaved 8 sites,suspected to be Type Ⅰ or ToxoDB#27 or ToxoDB#35;One sample successfully amplified and cleaved 6 loci,suspected to be Type Ⅰ or ToxoDB#24,ToxoDB#27,or ToxoDB#35.Conclusion This study conducted molecular detection and genotype identification of T.gondii infection in pigs in Jinzhong City,Shanxi Province.The positivity rate was high,and the positivity rate in lymphoid tissue was higher than in muscle tissue.ToxoDB#9 geno-type and suspected ToxoDB#9 or Type Ⅰ genotype samples were identified by PCR-RFLP.