Identifying Novel B Cell Epitopes within Toxoplasma gondii GRA6

The study of antigenic epitopes from Toxoplasma gondii has not only enhanced our understanding of the structure and function of antigens, the reactions between antigens and antibodies, and many other aspects of immunology, but it also plays a significant role in the development of new diagnostic reagents and vaccines. In the present study, T. gondii GRA6 epitopes were identified using bioinformatics tools and a synthetic peptide technique. The potential B cell epitopes of GRA6 predicted by bioinformatics tools concentrated upon 3 regions of GRA6, 1-20 aa, 44-103 aa, and 172-221 aa. Ten shorter peptides from the 3 regions were synthesized and assessed by ELISA using pig sera from different time points after infection. Three of the 10 peptides (amino acids 44-63, 172-191, and 192-211) tested were recognized by all sera and determined to be immunodominant B-cell epitopes of GRA6. The results indicated that we precisely and accurately located the T. gondii GRA6 epitopes using pig sera collected at different time points after infection. The identified epitopes may be very useful for further studies of epitope-based vaccines and diagnostic reagents.

Comparation of Toxoplasma gondii separated from HIV-positive people and RH strain GRA6 gene / 中国血吸虫病防治杂志

Objective To comparatively analyze Toxoplasma gondii separated from HIV-positive people and RH strain GRA6 gene. Methods By using the nested PCR the amplification of Dali HIV-positive blood samples and RH strains of Toxo-plasma GRA6 genome was performed. The GRA6 gene amplification positive product was selected and the electrophoresis imag-ing was performed by being digested with the Mse I endonuclease and the gene sequences were measured and analyzed. Re-sults The GRA6 gene fragment 800 bp was successfully amplified and about 600 bp and 200 bp bands were got by Mse I. The sequencing results showed that T. gondii GRA6 gene positive samples had 2 nucleotide variation compared with T. gondii strain RH namely 447 base pair at C becoming G and 623 base pair at G becoming T. At 146 bp and 690 bp the Mse I restric-tion sites TTAA were found. Conclusion The preliminary judgment shows that the Dali HIV-positive T. gondii genotype is consistent with RH strain belonging to genotype I.