Partial identification and characterisation of a Fasciola hepatica gene potentially useful for the immunodiagnosis

A lambda gt11 Fasciola hepatica cDNA library was screened with a serum from an infected woman. A first cDNA clone (FhH1a) of 547 bp with a poly(A) tai l at the 3' end and an Open Reading Frame (ORF)of 278 bp (92 AA) at the 5' end was isolated. This clone hybridised to a mRNA of about 2 kb in a Northe rn Blot analysis. Before looking further for the complete gene, immunogenic ity of the expressed protein was assessed by Western blotting using the imm une serum. A protein of about 10.3 kDa was expressed in Escherichia coli as beta-galactosidase fusion protein and appeared to be immunogenic. The 5' r egion of FhH1 was amplified using the rapid amplification of cDNA end PCR p rotocol (RACE-PCR) and 159 bp (52 AA) was found to complete the initial clo ne. The ORF of this new clone (FhH1c) had a potential coding capacity for a polypeptide of 145 AA residues with a calculated size of 16.2 kDa. An atte mpt was made to express this antigen in E. coli as Glutathione S-transferas e fusion proteins. The small amount of proteins obtained did not allow puri fication.