Studies On The Screening Of A Phage Display CDNA Library From Schistosoma Japonicum Adult Worm With Gynecophoral Canal Protein

Schistosomiasis caused by Schistosoma is widespread serious zoonosis. Schistosome is a rare variant form of male and female, and the pairing of male and female worms is prerequisite for the sexual mature of femle worm. The information transmission between male and female worms was carried out through pairing. Therefore, identifying those molecules which were responsible for the information transmission between male and female worms, may play an important role on investigating the cross-talk of male and female worms, the sexual development mechanism of Schistosome, and on the development of a vaccine against schistosome. Phage display technology is newly developed technology to display the fusion of exogenous peptide or protein with a specific phage capsid protein, has been widely used in molecular studies to identify mechanisms.In this study, a Schistosoma japonicum adult phage display cDNA library was screened with S. japonicum gynecophoral canal protein, some positive phage clones picked randomly were sequenced and analysied with bio-informatic techniques, and vaccine evaluation of some sequenced clones was carried out.After three series screening, the phage from the first series of 1.8×10-6pfu to the third series of 1.6×10-4pfu, nearly enrich 90-times, indicating success removal the non-specific and low-affinity binding of the phage. After sequencing and bioinformatics analysis of the phage clones picked at random. a total of 25 valid EST sequences were obtained, in which 20 EST sequences were homologous with known genes or expressed sequence tags and 5 EST sequences were not homologous with known genes or expressed sequence tags, as a new expressed sequence tags. The results of bioinformatics analysis about the 20 known sequence tags revealed that 10 EST sequences were the egg shell protein genes of S. japonicum, 3 EST sequences encoding ribosomal protein-related gene sequences, and 7 EST sequences encoded signal receptor partical subunit protein which function related with signal transmission.Vaccination of mice with 5 phage-displayed antigens obtained here weas carried out and the mice were challenged with S. japonicum. The results revealed that two groups immunized with phages displayed SJCHGC06360 protein (clone 19) and 2 unkown proteins (clone 6 and 18) of S. japonicum could induce high level protection with reductions of 40.53% and 31.14%(clone 19) and 35.31% and 44.65% (clone 6 and 18) for mean adult worm burdens and liver egg burdens, respectively. Detection of antibody levels showed that these two groups were made high specific antibodies.In conclusion, this paper firstly screened a Schistosoma japonicum adult phage display cDNA library with S. japonicum gynecophoral canal protein, obtained several positive clones, and found that SJCHGC06360 protein (clone 19) and 2 unkown proteins (clone 6 and 18) of S. japonicum might have some important function in reproductive development of Schistosoma and might be candidate vaccine antigen.