Screening For Diagnostic Antigen Of Toxoplasma Gonndii

Toxoplasma gondii is an intracellular zoonotic parasite.Congenital toxoplasmosis is a primary infection,which is closely related to intracranial calcification,hydrocephalus,growth retardation or other neurological defects in the fetus.An epidemiological survey of Toxoplasma gondii showed that about 213 of the 719 pregnant women had been infected with toxoplasmosis.In the world,about 30% of people suffer from this kind of disease,while the per capita infection rate in our country is 10%-47.3%.In the production and breeding of pigs,the clinical symptoms of toxoplasmosis are very similar to other viruses,which are prone to misdiagnosis and cause huge losses to animal husbandry production,so early detection,prevention and identification of these diseases are particularly important.Toxoplasma gondii can be divided into three stages in the host,namely,Tachyzoite,bradyzoite and sporozoite.There are great differences in protein profile expression in different stages,which often leads to missed detection,which seriously hinders the prevention and treatment of Toxoplasma gondii.At present,there are many kinds of immune techniques for detecting Toxoplasma gondii infection in China,mainly etiological examination,immunological detection et.al.Although the etiological detection method for Toxoplasma gondii detection has many advantages,but because of the high cost and complex operation,it has certain side effects on the human body,so it is not suitable to popularize.Enzyme-linked immunosorbent assay(ELISA)is one of the most commonly used detection methods in China,which has the advantages of simple operation,low cost and high sensitivity.In this study,purified recombinant proteins MIC3(secretory protein),SAG1(Tachyzoite stage)and BAG1(bradyzoite stage)of Toxoplasma gondii His tag were used as diagnostic antigens of Toxoplasma gondii.1166 human serum samples were detected by ELISA.It was found that there were differences in the detection results of the same batch of samples with different diagnostic antigens.The detection rates of Toxoplasma gondii from high to low were BAG1:10.5%(123 in 1166),SAG1:5.6%(65 in 1166)and MIC3:5.5%(63 in 1166).A total of 153 Toxoplasma gondii positive sera were detected with the three antigens,and the total positive rate was 13.12%(153 in 1166).In order to further verify the accuracy of the three antigens,1166 samples were reexamined by using the gold standard for diagnosis of Toxoplasma gondii infection-MAT method.This shows that there is still a phenomenon of missed detection of the combined antigen by indirect ELISA.To sum up,although the three antigens combined with ELISA detection can not completely detect recessive Toxoplasma gondii infection in the population,but the missed detection rate is lower than that of single antigen detection.The purpose of this study is to provide a theoretical basis for further accurate and specific detection of recessive infection of Toxoplasma gondii by ELISA method.