GENE CLOSING, OVERPRODUCTION AND PURIFICATION OF A FUNCTIONALLY ACTIVE CYTOPLASMIC FATTY-ACID-BINDING PROTEIN (SJ-FABP(C)) FROM THE HUMAN BLOOD FLUKE SCHISTOSOMA-JAPONICUM

We report the gene cloning, molecular characterisation and purificatio n of a 14.7-kDa functionally active recombinant (re) cytoplasmic fatty acid-binding protein (Sj-FABP(C)) from the Chinese strain of the huma n bloodfluke Schistosoma japonicum (Sj). As schistosomes are unable to synthesise long chain fatty acids and sterols de novo and must, there fore, take up these lipids from the host, Sj-FABP(C) is an attractive vaccine and/or drug target. Clone 39 (C39), which contains the entire Sj-FABP(C) gene, was isolated from a Sj lambda ZAPII cDNA expression l ibrary immunoscreened with hyperimmune rabbit serum (HRS) raised again st soluble adult Sj proteins. The complete ORF (open reading frame) of Sj-FABP(C) encodes a protein of 132 amino acids (aa) of 14.7 kDa. The aa sequence of Sj-FABP(C) exhibits 91% identity to a FABP of S. manso ni (Sm14) and 45% identity to a FABP of Fasciola hepatica (Fh15), puta tive vaccine candidates for schistosomiasis. Sj-FABP(C) was subcloned into the QIAexpress vector, pQE-10, and subsequently expressed in Esch erichia coli. The re-Sj-FABP(C), purified under non-denaturing conditi ons, was recognized by sera from patients with acute and chronic schis tosomiasis japonica. The purified re-Sj-FABP(C) was also shown to bind to palmitic acid with high affinity. The functional expression of Sj- FABP(C) will facilitate studies on re-Sj-FABP(C) to assess its potenti al as a drug and/or vaccine candidate.