Study On The Distribution Difference Of Toxoplasma Gondii In Sheep Tissues And Organs

Toxoplasma gondii(T.gondii)is an important foodborne parasitic protozoa of zoonotic origin.Sheep is an important meat source all over the country,and it is also a susceptible animal to T.gondii.Eating sheep infected with T.gondii will pose a serious threat to the food safety of consumers.At present,the research on T.gondii in sheep mainly focuses on the infection rate,and there is no detailed study on the distribution of T.gondii in different internal organs and muscle tissues of sheep.Therefore,understanding the distribution of T.gondii in mutton is of great significance to the development of meat food safety.In this study,the serum positive sheep were determined by ELISA antibody detection,and then the sheep that can amplify T.gondii B1 gene were determined by PCR amplification.The different visceral and muscle tissues of positive sheep were relatively and absolutely quantified by fluorescence quantitative PCR.The results showed that the infection rate of T.gondii in 115 sheep was 32.2%;The heart parts of 7 serum positive sheep were amplified,of which 5 could amplify T.gondii B1 gene,and all other sampling parts of these 5 sheep could amplify T.gondii B1 gene;The relative quantitative results showed that the relative expression of T.gondii in visceral part was high,among which the heart was the highest(201.23),and the outer ridge(49.79)and inner ridge(48.12)in muscle part were the highest.The relative expression from high to low was as follows: heart,spleen,outer ridge,inner ridge,lung,liver,kidney,neck meat,upper brain,front tendon,front leg,cucumber strip,rear leg,rear tendon,chest,lamb belly,lamb chop.The absolute quantitative results showed that the distribution trend of T.gondii was consistent with the relative quantitative results.The highest log copy number in the heart was 2.48±0.04,and the lowest was 1.74±0.03;the highest log copy number in the outer ridge was 1.92±0.02,and the lowest was 1.29±0.01;there was significant difference in T.gondii content among5 sheep.In conclusion,T.gondii infection exists in both viscera and muscle tissues of sheep,and the amount of infection between viscera and muscle tissues is different.In this experiment,the distribution of T.gondii in sheep was studied in detail for the first time,which improved the detection scope of mutton food safety,and provided data support for the development of meat food safety.