Selection And Study On Mimic Peptides Of Toxoplasma Gondii

Toxoplasma gondii is a protozoan parasite that can infect aves, mammal and human beings. It is transmitted via three primary ways, congenitally, by ingestion of food and water contaminated with sporulated oocysts from infected cat feces, and by the ingestion of undercooked meat containing tissue cysts. Cats are the only host that can excrete the environmentally resistant oocysts. It is an important cause of abortion and mortality in sheep and goats throughout the world. It causes mental retardation and loss of vision in congenitally infected children and death in immunosuppressed patients.In this research, the random phage display peptide library was screened by anti-T.gondii polyclonal antibody. After three rounds of screening, 50 positive colonies (37 colonies of 12-peptide, 13 colonies of cycle-7-peptide) that have specificity and high affinity to the polyclonal antibody were selected out by ELISA technique. Then, the DNA sequences of target colonies were sequenced. 25(19 colonies of 12-peptide, 6 colonies of cycle-7-peptide) out of 50 peptides have the potential conservative WH/WHH or WH/WxH motif. 13 colonies of 12-peptide have the potential conservative SP/SxP motif. Comparing these sequences with the sequences of native Tox-Ags, we found they had the same or similar short sequences. dot-ELISA and Western Blotting were used to identify the specificity between the target peptides and the polyclonal Ab. They had a single line at about 66kD in Western Blotting. Immunizing mice with some positive colonies was used to test the protection of the phages. We saw they helped mice resist T.dondii, extended their lives evidently, but couldn't make them alive.This research explored a new convenient approach to obtain mimic peptides of Toxoplasma gondii. They have potential value in clinical applications and development of new bacterin.