Antigenic Community between Opisthorchis viverrini Adult Worms and Their Intermediate Hosts, Bithynia Snails as a Support for Concomitant Antigens

Abstract

Abstract

The concept that parasites share antigens with their snail intermediate hosts has received considerable experimental support. In this study, comparison between three species of Bithynia snails: B. funiculata, B. siamensis siamensis, B. siamensis goniomphalos and crude somatic antigens of Opisthorchis viverrini adult worms were immunologically characterized with antibodies (IgG) in sera of opisthorchiasis patients by SDS-PAGE and Western blot analysis. All of these snail antigens reacted with O. viverrini infected human sera, which revealed only 13-15 protein bands by Western blot analysis when compared with sera from healthy controls. B. funiculata was proven to have more shared antigens with O. viverrini than the other two species, particularly three pairs with molecular weights (MW) of 29 and 30, 47 and 50, and 86 and 90 kDa, which reacted consistently with all infected sera. Extensive cross reactions of the B. funiculata snail antigen with sera from patients with other parasitic infections still occurred. However, the three pairs of proteins mentioned above mostly failed to give any cross reaction with the sera of paragonimiasis, schistosomiasis, fascioliasis, sparganosis, larval toxocariasis, trichuriasis and capillariasis, or at least just one or two protein bands out of the six appeared to cross react with sera of taeniasis, cysticercosis, echinococcosis, gnathostomiasis, angiostrongyliasis, trichinosis, ascariasis, filariasis, strongyloidiasis, hookworm infections and HIV infections. This study suggests that the antigen prepared from B. funiculata snails, one of the snail intermediate hosts of O. viverrini, could possibly be used as an alternative diagnostic antigen for opisthorchiasis in the future.

Keywords : shared antigens, Bithynia funiculata, B. siamensis siamensis, B. s. goniomphalos, Opisthorchis viverrini, Western blot analysis