FASCIOLA-HEPATICA - RAPID SWITCHING OF STAGE-SPECIFIC ANTIGEN EXPRESSION AFTER INFECTION

Early developmental stages of the trematode parasite Fasciola hepatica were collected from the peritoneal cavity and liver of mice during a ten day infection period. Using one dimensional SDS-PAGE, differences in protein expression profiles were observed in stages collected on th e same day post-infection in different physiological locations and als o in juvenile parasites collected from the same location on different days post-infection. Four rat monoclonal antibodies were raised agains t the parasite using lymph nodes draining infected tissues. Three mono clonal antibodies, FY3-1, FY3-2 and FY4-7, were generated using cells from the mesenteric lymph node of recently challenged immune mts, whil e FY1-6 was derived from hepatic lymph node cells of a chronically inf ected rat. The epitope recognized by FY3-2 appeared to be carbohydrate in nature and was present on the surface of newly excysted juveniles. Immunoblots revealed that the antigens recognized by FY3-1, FY3-2 and FY4-7 were only expressed for two days after infection. In contrast, FY1-6 recognized epitopes expressed across all developmental stages sc reened. The rapid changes in protein and antigen expression observed d uring the early stages of infection may assist the parasite to evade t he host immune response.