Identification and Characterization of Novel Antigens from Opisthorchis viverrini

Abstract

Opisthorchis viverrini is the causative agent of human opisthorchiasis in Thailand.
Long lasting infection with the parasite has been correlated to the development of
cholangiocarcinoma. This kind of cancer is a major public health problem in North- and
Northeast-Thailand. At present, the knowledge which parasite antigens are involved in the
establishment of infection and tumorigenesis is quite limited. We have, therefore, screened
the published parasite transcriptome sequences to identify new antigens which might be
involved in the host/parasite interaction. Two related transcripts were selected due to a
suspected function of the encoded proteins (OvDM9A, OvDM9B) in the transport of
hydrophobic molecules. The corresponding cDNAs were isolated from an adult stage O.
viverrini cDNA library and subcloned into bacterial expression vectors. Recombinant
proteins were produced in E. coli but were insoluble. Only OvDM9A was selected for further
analyses and the purified recombinant protein has been used for production of polyclonal
antisera in mice. The antisera will be used to localize native OvDM9A in parasite antigen
extracts and tissues. To study its biochemical function OvDM9A will be expressed in yeast to
obtain soluble protein which will be tested in binding assays with hydrophobic molecules.
The biological function will be studied in vivo using RNAi to analyze if the protein is
essential for parasite survival in the host. If a role in binding and transport of hydrophobic
molecules can be established these novel proteins could be useful for drug targeting.