Identification and immunological characterization of Echinostoma liei antigens: preliminary study for validation of its use in schistosomiasis control program

ABSTRACT

Several studies have proposed the use of larvae of Echinostoma in schistosomiasis biological control program, since Echinostoma rediae attack and even destroy S. mansoni sporocysts probably by induction of host's inflammatory response when they are in the same molluscan. The objective of the present work was to identify and immunologically characterize E. liei antigens to be presented as a promising tool in schistosomiasis control program. Two E. liei antigens were prepared namely metacercarial and adult worm antigens in addition to Schistosoma soluble egg antigen [SEA] and Schistosoma worm antigen [SWAP]. Analysis of the four antigens by sodium dodecyl sulphate polyacrylamide gel electrophoresis [SDS-PAGE] revealed a number of bands except for the metacercarial antigen of E. liei which appeared as a single band. Immunoblotting revealed three common bands between SEA, SWAP and E. liei worm antigen corresponding to 17, 29 and 97 kDa. Detection of specific total IgG and IgG4 isotype in sera of S. mansoni infected patients were measured by ELISA using all four studied antigens. The levels of both IgG and IG4 isotype showed no statistical significant difference between schistosomal SEA, SWAP and worm E. liei antigens. On the other hand, metacercarial antigen revealed statistically significant lower levels of both IgG and IgG4 when compared with schistosomal SEA [p< 0.05]. The highest sensitivity and specificity rates for detection of specific total IgG and IgG4 isotype were recorded when using schistosomal SEA. Owing to its rather promising results, further studies are needed to investigate the possible validity of using E. liei adult worm antigen in snail immunization against schistosomiasis especially in endemic areas where re-infection is commonly encountered