Molecular cloning, expression and vaccination of a novel gene Sj-MA of Schistosoma japonicum.

In order to obtain new gene and to develop the new vaccine candidate of immunoprotection against Schistosoma japonicum (Sj), Sj adult worm cDNA library was screened with anti-sera to soluble male adult worm antigen and resulted in the discovery of a novel gene designated as Sj-MA. Sequence analysis showed that Sj-MA as a complete cDNA contains one open reading frame. It was deduced to contain 249 amino acid residues and encode a 28.8 kD soluble protein with plenty of phosphorylation sites, supposing its action in signal transduction. Furthermore, Sj-MA cDNA was cloned into a prokaryotic expression vector pGEX-5X to construct the recombinant plasmid which was transformed and highly expressed in E. coli as a 54.8 kD glutathione-S-transferase (GST) fusion protein. The fusion protein rSj-MA/GST could be recognized with both anti-male adult worm sera and anti-GST sera in Western blotting. Mice vaccinated with the fusion protein revealed significant worm reduction rate of 34.29% (P<0.001), compared with the control groups. Taken together, the novel gene Sj-MA can be expressed in E. coli as a fusion protein that can elicit immunity against Schistosoma japonicum, suggesting its potential as a new vaccine candidate.