Successful detection, expression and purification of the alternatively spliced truncated Sm14 antigen of an Egyptian strain ofSchistosoma mansoni

Abstract

Schistosoma mansoni causes intestinal schistosomiasis, a disease that is prevalent in several regions worldwide. To date, a protective vaccine against S. mansoni is still lacking. Several promising antigens have been discovered and evaluated for vaccine protection, such as Sm14 and Sm28GST. In this short communication, we report the successful detection of an alternatively spliced truncated form of Sm14 which was highly expressed in an Egyptian strain of S. mansoni. This truncated Sm14 (TrSm14) protein was formerly reported to be practically non-existent and its complementary DNA (cDNA) was thought to be 'a rare misprocessing of mRNA precursor'. Our finding demonstrates that there is inter-strain variation in the S. mansoni transcriptome and subsequently in the role/function of the expressed proteins. We expressed TrSm14 successfully in Escherichia coli as a fusion protein with the schistosomal antigen Sm28GST. The fusion protein was purified using metal affinity chromatography and was found to be reactive with serum from S. mansoni-infected patients. This suggests a possible diagnostic value for this protein in detection of anti-schistosomal antibodies. In addition, this fusion protein could offer a potential bivalent vaccine candidate against S. mansoni that is worthy of further investigation.