THE PEROXIDOXIN-2 PROTEIN OF THE HUMAN PARASITE ONCHOCERCA-VOLVULUS -RECOMBINANT EXPRESSION, IMMUNOLOCALIZATION, AND DEMONSTRATION OF HOMOLOGOUS MOLECULES IN OTHER SPECIES

The peroxidoxin protein of the filarial parasite Onchocerca volvulus ( OVPXN-2) belongs to a group of highly conserved antioxidant molecules. For a more detailed characterization of this protein and for determin ation of its expression pattern the OvPXN-2 protein was recombinantly expressed as a His-tagged protein. Under reducing conditions the recom binant protein had an apparent molecular mass of 28 kDa. Considering t he size of the His-tag and the FLAG epitope introduced to the recombin ant protein, this size is in agreement with that of the native protein identified in O. volvulus extract. Antiserum raised against the recom binant protein was used for immunolocalization. In O. volvulus the ant igen is predominantly expressed in the hypodermis and particularly the lateral and median chords show high levels of expression. The protein is also expressed strongly in the hypodermis of infective larvae and more weakly in microfilariae. Related cross-reacting proteins were det ected in several Onchocerca species and other filariae. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis in combination with Wester n blotting revealed proteins with almost identical mobility in extract s prepared from O. ochengi, O. gibsoni, and Dirofilaria immitis.