Molecular characterization of Schistosoma haematobium species-specific diagnostic antigen (gp23) using cDNA library in E. coli

Abstract

A Schistosoma haematobium cDNA library constructed in λgt-22 was immunoscreened using monospecific anti-gp23 antibodies raised in C57B1/6 mice. One positive clone was obtained by PCR using B+ and B− primers of λgt-22. The PCR product of the clone was of 605 bp. To identify the sequence of the positive clone, it was subcloned into plasmid vector (PCR™ II) and its nucleotide sequence was determined using dideoxy nucleotide termination method. The full-length sequence has a 19 nucleotides poly A tail. The data base analysis revealed a high degree of similarity between the gp23 DNA sequence and the S. haematobium heat shock protein 70 (Hsp70) with 95.8 % identity. Software analysis of the full length of gp23 sequence revealed a long ORF that encode 21.86 kDa protein of 198 amino acids. The sequence submitted to Gene bank under accession number (JN712654) ( http://www.ncbi.nlm.gov ). Results of the present work indicate that the gp23 antigen recognized by the monospecific sera is highly immunogenic and related to the Hsp70 family. Further plans will include expression of the immunogenic molecule encoded by the clone of 605 bp. The specificity and sensitivity of the recombinant form of the serodiagnostic antigen will evaluate before large-scale production.