Analysis And Identiification Functional Components Of Toxoplasma Gondii Excreted-secreted Antigen

Toxoplasma gondii is an obligate intracellular apicomplexan parasite that can cause severe andlife-threatening diseases in humans and animals. T. gondii infection is perhaps one of the most prevalentparasitic infections of humans in the world, with at least one third of people being infected. Under thepresent scenario, development of an effective and safe vaccine was an attractive alternative. The key ofdeveloping effective vaccine is finding the suitable antigen, which can efficiently stimulate hostto produce a protective immune response against T. gondii. Previous studies revealed thatexcreted-secreted antigens (ESA) of T. gondii play an important role in the stimulation of the protectiveimmune system. Subsequently, researchers pay more and more attention on ESA, and they also believeESA will be one of the best vaccine candidates. To analyze the component of ESA, a lot of work hasbeen done, but, to date only a limited number of secretory proteins have been discovered. ESA maycontain many unknown proteins and some of them may be effective antigens. So it’s necessary for us toidentify those proteins and analyze the antigenicity of them.The second part of present study, SDS-PAGE combined with LC-ESI-MS/MS was used to identifythe proteins of T. gondii ESA from mouse peritoneal fluid,850proteins were successfully identified, ofwhich119proteins belong to T. gondii. Functional analysis using Gene Ontology database showed thatthese T. gondii proteins were mainly involved in7kinds of protein function,8kinds of cellularcomponents and19kinds of biological processes. Previous study showed that some of these proteinshave good immunogenicity, including surface antigen1, microneme protein, rhoptry protein, granuleantigen protein, pyruvate kinase, protein disulfide isomerase, heat shock protein, enolase,glyceraldehyde-3-phosphate dehydrogenase and so on, but the immunogenicity of others should befurther research. The findings would provide a reference for further study on the componets of T. gondiiESA and looking for a new candidate molecule for the development of vaccine against T. gondii orbiomarkers for diagnosis.The third part of this study,27positive protein points were detected by using immunoproteomics,which showed that T. gondii ESA from mouse peritoneal fluid had good immunogenicity. Meanwhile,comparative analysis of proteomes between T. gondii-infected and non-infected mouse peritoneal fluid,119differential expressed protein spots were detected, which is useful for understanding the interactiverelationship between T. gondii and the host and providing a new method against T. gondii. The last partof our study detected18positive protein points,6proteins spots were selected to identify byLC-MS/MS, which corresponded to4proteins matching to proteins of T. gondii including micronemeprotein1, mieroneme protein4, cyst matrix protein,14-3-3protein. They showed that these proteinshave great immunogenicity.In summary, the present study explored proteomics to analyse the componets of T. gondii ESA andscreen antigens with immunogenicity, as well as comparative proteomics was used in present study, which provide a reference for looking for new candidate molecular for prevention and diagnosis oftoxoplasmosis.