Molecular characterization and serodiagnosis analysis of a novel lysophospholipase from Clonorchis sinensis

A cDNA clone encoding a novel lysophospholipase with a predicted molecular weight of 25.2 kDa was isolated from a Clonorchis sinensis adult cDNA library. The enzyme activity of the recombinant protein expressed in Escherichia coli was determined using phosphatidylcholine and lysophosphatidylcholine as substrates. Western blotting analysis indicated that it belonged to excretory/secretory proteins of the adults. The sensitivity and specificity of the recombinant antigen for serodiagnosis were evaluated with immunoglobulin enzyme-linked immunosorbent assay using serum samples from 20 patients with clonorchiasis and 20 patients with schistosomiasis. The sensitivity (75%) and specificity (80%) of the recombinant protein were comparable to those of crude extracts, at 65 and 82.5%, respectively. The sensitivity of the recombinant protein was 77% using 100 serum samples of clonorchiasis patients with various parasite burden. The results suggested that the recombinant lysophospholipase protein was not a satisfactory candidate for diagnosis of clonorchiasis, although it might be an excretory/secretory protein.