Cloning and characterization of Clonorchis sinensis myoglobin using immune sera against excretory-secretory antigens

Clonorchis sinensis excretory-secretory (ES) antigens were separated by gradient SDS-PAGE and the antigenic protein isolated at 21 kDa was injected into rats. A C. sinensis cDNA library was then immunoscreened with sera from the 21-kDa antigenic protein-immunized rats. The selected genes, which were named C. sinensis myoglobin, contained a single open reading frame of 450 base pairs encoding 150 amino acids. A single hybridized band of 0.57 kb and two to four hybridized bands were detected by Northern and Southern blotting. Purified recombinant C. sinensis myoglobin was recognized by clonorchiasic rabbit sera (50%) and clonorchiasic human sera (25%). An indirect immunofluorescence assay showed that C. sinensis myoglobin is distributed over the whole body of the adult worm. It is believed that the abundance of C. sinensis myoglobin plays an important role as an oxygen reservoir under anaerobic conditions.