Toxoplasma gondii: Proteomic analysis of antigenicity of soluble tachyzoite antigen

Exp Parasitol. 2009 Jan 29. [Epub ahead of print]

Toxoplasma gondii: Proteomic analysis of antigenicity of soluble tachyzoite antigen

Ma GY, Zhang JZ, Yin GR, Zhang JH, Meng XL, Zhao F.

Research Institute of Medical Parasitology, Shanxi Medical University, P. R. China; National Institute for Communicable Disease Control and Prevention (ICDC), Chinese Center for Disease Control and Prevention (China CDC), P. R. China.

The obligate intracellular parasite Toxoplasma gondii is an important pathogen of humans and animals. The tachyzoite of T. gondii is the main life-cycle stage that is responsible for toxoplasmosis. Study of the antigenicity of soluble tachyzoite antigen (STAg) is important for discovery of protective antigens which will aid in the detection and prevention of toxoplasmosis. At present, no complete proteome map of T. gondii STAg is established, although a large-scale whole proteomic analysis of tachyzoites is underway. In this study, 1227 protein spots of T. gondii soluble tachyzoite antigen (STAg) were fractionated by 2-dimensional electrophoresis (2-DE) at pH range 3-10. By mass spectrometry (MS) analysis, among the separated 1227 protein spots, 426 were identified by searching the Swissport and NCBI nr databases. 230 of these identified spots (230/426, 54%) were demonstrated to be T. gondii protein by MS. Of the 21 Toxoplasma protein spots identified by western blot with rabbit anti-T. gondii serum, 16 had immunoregulatory functions and 5 had immune defense functions. Due to multiple spots for a single protein, these 16 spots represented 11 proteins: a putative protein disulfide isomerase (PDIs), a heat shock protein 60 (Hsp60), a pyruvate kinase (PK), a putative glutamate dehydrogenase (GDH), a coronin, a heat shock protein 70 (Hsp70), a protein kinase C receptor 1 (RACK1), a malate dehydrogenase (MDH), a major surface antigen 1 (SAG1), an uridine phosphorylase (UPase) and a peroxiredoxin (Prx). Among the identified 11 proteins, except that the antigenicity and immunogenicity of the SAG1 has been reported and antigenicity of Hsp70 has disputed, the remaining antigenic proteins were first identified in this study. In conclusion, we obtained 9 novel types of immunogenic proteins that might be potential candidates of vaccine development for toxoplasmosis, which we will confirm in later studies.

PMID: 19545523 [PubMed - as supplied by publisher]