Serological Investigation Of Toxoplasma Gondii In Animals In Some Areas Of Jiangsu Province And The Establishment Of Porcine Toxoplasmosis Model By Artificial Infection

Toxoplasmosis is a serious zoonotic disease which can infects humans, mammals and birds in the world. Porcine toxoplasmosis was first reported by Farell in the U.S. and toxoplasma gondii was isolated from pigs in1959in china. Porcine toxoplasmosis was more serious in the United States, Japan and other countries.During the70years of last century, toxoplasma gondii is one of the factors of the outbreak of "nameles-s fever" in pigs. The disease often occurred in pigs of3-4months old, with a mortality rate of30-40%, and piglets has the highest mortality rate while adult swine has a low morbility with a latent infection or a slight symptoms.In order to ascertain the prevalence trends of toxoplasmosis in animal groups, we did a serological survey on the animals of parts of Jiangsu province (Xuzhou, Lianyungang, Yancheng, Suqian, Nantong, Taizhou, Yangzhou, Nanjing, Changzhou, Yixing,and Kunshan). Use indirect hemagglutination (IHA) to detect the antibodies of Toxoplasma gondii. When the serum samples was at1:64dilution, we regarded the serum samples was positive while the allergen level in blood agglutination "++" more than50%.Results displayed that145samples was Toxoplasma gondii antibodies positive during the total1100samples with a positive rate of13.2%, and120samples was positive during939swine serum samples with a positive rate of2.8%, which reflected the level of Toxoplasma gondii infection in animals of Jiangsu Province.As it is difficult to detect the antigen of Toxoplasma gondii, we established a PCR detection method to improve the the detection rate of Toxoplasma gondii antigen in tissue samples. B1gene was used to establish a PCR method, and a certain number of Toxoplasma tachyzoites were diluted to1.34×10-5、6.69×10-6,3.35×10-6.1.67×10-6、8.36×10-6、4.18×10-7.2.09×10-7,1.04×10-7、5.2×10-8、2.6×10-8μg DNA by serial dilution method to determine the concentration of PCR, detection the cysts formating in the mouse brain which infected by Toxoplasma gondii chronically.The results showed the PCR method can detect5.2×10-8μg Toxoplasma gondii DNA, and can detect the DNA with cysts in mouse brain with chronic infection of Toxoplasma gondii.Redarding NT strain as a base strain, intramuscular injection (5million of Toxoplasma gondii tachyzoites), intraperitoneal injection (50million of Toxoplasma gondii tachyzoites) and intraperitoneal injection (100million of Toxoplasma gondii tachyzoites) were used respectively to infectd the30-day-old weaned piglets. Results showed that after3-7days of infection there was a typical symptoms of toxoplasmosis with continuous high temperature, mental fatigue, difficulty breathing, loss of appetite, and turned to chronic toxoplasmosis or died in the course of the disease, which confirmed that we established the porcine toxoplasmosis model by articial infection,and preliminary establest the standard of porcine toxoplasmosis by articial infection.The serological survey of animal Toxoplasmosis in Jiangsu province indicate that the disease prevalences allover the province. Nested-PCR method provide a strong technical support for the evaluation of the biological safety of UV-induced weak live vaccine insect-infected.The establishment of artificial incidence of Toxoplasma gondii pig model provide a solid foundation for the evaluation of the immune effect of UV-induced weak live vaccine strain.