Venom allergen-like protein 28 in Clonorchis sinensis: four epitopes on its surface and the potential role of Cys124 for its conformational stability

Parasitology Research - Venom allergen-like (VAL) proteins are important to host-parasite interactions. We previously demonstrated that a Clonorchis sinensis VAL (CsVAL) protein-derived synthetic...     

The identification of antigenic proteins: 14-3-3 protein and propionyl-CoA carboxylase in Clonorchis sinensis

Clonorchis sinensis, the causative agent of clonorchiasis, is widespread in East and Southeast Asia, including China, Vietnam and the Republic of Korea. We identified antigenic proteins from adult C. sinensis liver flukes using immunoproteomic analysis. In this study, we found 23 candidate antigenic proteins with a pI in the range of 5.4-6.2 in total lysates of C. sinensis. The antigenic protein spots reacted against sera from clonorchiasis patients and were identified as cysteine proteases, glutathione transferases, gelsolin, propionyl-CoA carboxylase (PCC), prohibitin and 14-3-3 protein (14-3-3) using LC-coupled ESI-MS/MS and an EST database for C. sinensis. PCC and 14-3-3 were identified for the first time as serological antigens for the diagnosis of C. sinensis. To validate the antigenicity of PCC and 14-3-3, recombinant proteins were immunoblotted with sera from clonorchiasis patients. The structural, functional and immunological characteristics of the putative amino acid sequence were predicted by bioinformatics analysis. Our novel finding will contribute to the development of diagnostics for clonorchiasis. These results suggest that immunoproteomic approaches are valuable tools to identify antigens that could be used as targets for effective parasitic infection control strategies.     

Identification and characterization of a novel 21.6-kDa tegumental protein from Clonorchis sinensis

Tegumental proteins form a membrane-bound outer surface and are thus involved in host–parasite interactions and parasite survival. A complementary DNA clone encoding a novel 21.6-kDa tegumental protein (CsTegu21.6, accession number JF911532) was identified in a sequence library for the adult Clonorchis sinensis liver fluke. The complete coding sequence was 564 bp and encoded a protein of 188 amino acids. A BLASTX search revealed identities from 43 to 47% with previously identified tegumental proteins in C. sinensis and other helminthic parasites. Multiple alignment of the amino acids of CsTegu21.6 with those of four other C. sinensis tegumental proteins, CsTegu21.1, CsTegu22.3, CsTegu20.8 and CsTegu31.8, revealed pair-wise sequence identities ranging from 24 to 31.8%. A calcium-binding EF-hand domain containing a basic helix–loop–helix structure at the N terminus and a dynein light chain domain at the C terminus were found in CsTegu21.6; these motifs are common in tegumental proteins. CsTegu21.6 was specifically observed on the tegument of adult worms using immunolocalization analysis.