Construction Of Phage Display CDNA Library From Adult Worms Of Schistosoma Japonicum And Screening Of Genes Related To The Schistosoma-resistance Of Microtus Fortis

Schistosoma japonicum is agent of zoonotic infection which can result in serious disease both humans being and in the domestic animal reservoir hosts. Microtus fortis is the only one mammalian animals with resistance to schistosomiasis found in the epidemic area in China. It could provide new technique and new idea for exploitation of anti-schistosomiasis vaccine and treatment drug to screen and clone the genes related to the Schistosoma-resistance of Microtus fortis.Phage display is a recently established and developed new technique that express exogenous gene, which was generally utilized in researching intermolecular recognition mechanism. Here, we first constructed phage display cDNA library from adult worms of Schistosoma japonicum, and screened the library using negative serum of Microtus fortis, in order to find the genes related to the Schistosoma-Resistance of Microtus fortis.Method and results1. A T7 phage display library from adult worms of Schistosoma japonicum was constructed: Primary library capacity was 4.98×10⁶ pfu, and the titer of amplified library was 3.85×10¹¹ pfu/mL. The PCR identification result of 96 clones picked at random showed that recombination rate was 93.8%, in which 95.6% inserted cDNA fragments were longer than 300bp in length. All of Seven known objective genes of Schistosoma japonicum were amplified from the library.2. Screening the genes related to the Schistosoma-resistance of Microtus fortis: Negative serum of Microtus fortis was used to screen the library by biopanning. After three rounds screening, 10 ESTs were obtained, 7 of had high similarity with the genes of Schistosoma japonicum in GenBank, the similarity reached 99%～100%; 1 of them have 82% similarity with the gene other species; the other two genes were no significant genes found. Results of function prediction showed that the functions of codogenic protein or peptide of ESTs are mainly binding, enzyme activity and constituent of constitutive protein.Conclusion A T7 phage display library from adult worms of Schistosoma japonicum wassuccessfully constructed and 10 ESTs related to the Schistosoma-resistance of Microtus fortis were obtained in our studies. The results laid the groundwork for further explaining the mechanism related to the Schistosoma-resistance of Microtus fortis and searching antigen candidate of anti-schistosomiasis vaccine.