Identification and molecular characterization of membrane antigen gene(s) of Schistosoma haematobium
Ali, Mohamed Aden
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In the last decade substantial resources have been invested to identify, characterize and purify various schistosome antigens for the purpose of designing and testing potential vaccines. The investigation of the schistosome tegumental antigen gene(s) was based upon the fact that the unusual structure of the tegument in the adult schistosomes is an adaptation to survival in the blood stream of the human host. The hypothesis put forth in this study was that the tegument proteins of the adult S. mansoni could be potential vaccine immunogens. The membrane proteins from the S. mansoni were extracted and characterized on SDS-polyacrylamide gel electrophoresis. Rabbit anti sera were then raised against the membrane extract. Western blot analysis revealed conspicuous immuno-bands of 84,26 kDa. Thereafter an adult S. haematobium cDNA expression library was screened using rabbit anti-S. mansoni membrane sera. Several immunocreative clones were isolated by the screening exercise and the presence, size of the 0.5 to 1.3 Kb. Two of teh clones (Sh 3-4, Sh 4-1) with insert sizes of 0.5 and 0.9 Kb were sub-cloned into the pMOS-plasmid vector (Amershan, UK) and sequenced partially using Sanger's dideoxy chain termination method. Sequence homology search through the Gene bank data base showed that both clones contained membrane encoding genes. One clone had 94% nucleotide identity to S. mansoni myosin encoding gene. The other one scored 98% homology to dynein light chain of S. mansoni and 77% nucleotide identity to T-cell stimulating antigen of S. mansoni. Therefore, these antigen genes are likely candidates that could contribute to the development of a sub-unit vaccine against schistosomiasis.
- MST-Zoological Sciences