The Seroprevalence In Some Districts Of Henan Province And Genotyping The Isolates Of Swine Toxoplasma Gondii

Toxoplasmosis is caused by Toxoplasma gondii that is an obligate intracelular protozoan pathogen.T.gondii can infect various animals,including humans,especially is of the high morbidity and mortality for swine.It was reported that the rate of swine infected by T.gondii was 4.8 to 85.7 percent.Toxoplasmosis has complicated clinical symptoms because T.gondii can infect different tissues,which causes inconvenience in diagnosis and prevention in early phases.Therefore,it is important to look for a more effective method to diagnose Toxoplasmosis.T.gondii has a widely hosts.On different hosts,it can show different biology characteristics.Therefore,the study on genetics and epidemiology of T.gondii is of importance for prevention and treatment.In the past,the determination of genotypes of T.gondii strains based on pathogenicity in mice which discriminated virulent strains from avirulent strains.With the rapid development of molecular genetics,genetic typing methods of T.gondii strains have been extensively performed in the recent years.Typing,virulence and distribution of different T.gondii strains in the level of molecular genetics divides all strains into multiplex genotypes and makes us know the regular pattern of genotypes with different districts and hosts.The diagosis for T. gondii in the molecular genetics will provide effective measure to prevent it. 1 To understand seroprevalence of Toxoplasmosis in Henan Province,the author randomly collected some swine serum from different 6 districts and applied IHA method to detect the IgG antibody.The result:304 samples was positive in collected 2325 serum samples,and the presence of positive samples of piglets and sows were 13.2%和15.1%,separately.2 To abtain more Toxoplasma gondii positive strains,the author analyzed some suspect tissues with Gimsa dying method.Besides,the positive samples with IHA were again analyzed by ELISA.The method could save financial capability.The result:3 positive strains were found and also resulted from piglets.3 To understand the time of IgG antibody of Toxoplasma gongdii to produce and disappear in infected mice,the author developed a infected animals model.After positive tissues were grinded,equal normal saline were added to it and filtered.Mices were injected with filtered liquor into abdominal cavity.The result shows that the infected first-generation mices have no IgG antibody of Toxoplasma gongdii,but after 5 days,infected second-generation mites were found that IgG antibody was positive by IHA method.After 7 days,IgG antibody was high to 1:2560 and typical trophozoite were found in mice tissues with gimsa dying method.4 Base on Toxoplasma gondii B1 gene,the author designed one pair of primer for PCR for the clinical diagnosis of Toxoplasmosis.We were able to amplify the DNA of a single organism directly from a crude cell lysate.The sensitivity also allowed us to detect the B1 gene from purified DNA samples containing as few as 10 parasites in the presence of 100,000 human leukocytes.No signal was detected by this assay that DNA from a variety of other organisms,including several which might be found in the central nervous system of an immunocompromised host.This combination of sensitivity and specificity should amplified effectively the B1 gene with PCR.This is a very useful method for diagnosis of toxoplasmosis both in immunocompromised hosts and in congenitally infected fetuses.5 In order to understand the genotype of the isolates,a multiplex PCR assay was designed for multilocus genotyping of Toxoplasma.gondii strains based on polymorphism of five microsatellite markers.RH T.gondii strains is genotype I,which is identical with previously reported.While,other 3 strains areⅡ/Ⅰrecombinant genotype.