Immunoprecipitation analysis of radiolabelled protein antigens biosynthesized in vitro by S. mansoni. I. Identification of antigens uniquely recognized by protective antibodies.
Protein antigens from 4-wk worms were metabolically radiolabelled with [3H]leucine or [35S]methionine. Three freeze-thaw cycles released a large proportion (50% to 60%) of the TCA-precipitable radioactivity from the worms. Immune serum from twice-infected Fischer rats (F-2x), which was shown to confer resistance in a passive immunization assay, and immune serum from twice-infected Wistar Furth rats (W-2x), which does not confer resistance, were used for analyzing antigens in this worm fraction. Antibodies in these antisera differed in their titers to the freeze-thaw released antigens (W-2x greater than F-2x) and in their relative affinities for these antigens (F-2x greater than W-2x). Gradient slab gel electrophoresis of immunoprecipitates of radiolabelled antigens under denaturing conditions revealed many components, which could be categorized into two main types: unique antigens, recognized only by F-2x antibodies, and nonunique antigens, recognized by both F-2x and W-2x antibodies. The potential relevance of these antigens in resistance was further examined by antibody absorption experiments in which 4-wk worms were used as an immunoabsorbent to remove 90% to 95% of the immunoprecipitating activity and 65% to 70% (p less than 0.005) of the capacity to confer resistance in a passive immunization assay. It was concluded that loss of both anti-schistosome activities was specific since antigen released by worms during absorption could account for only 16% of the reduction in antigen-binding capacity and the titer of antibodies directed against beta-galactosidase did not significantly change during absorption. Antigens recognized uniquely by F-2x antibodies are therefore candidates for immunization studies examining induction of resistance against Schistosoma mansoni.
D000042:Absorption; D000818:Animals; D000937:Antigen-Antibody Reactions; D000947:Antigens, Helminth / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D007106:Immune Sera / Q000008:administration & dosage / Q000032:analysis / Q000276:immunology*; D007113:Immunity, Innate; D007116:Immunization, Passive; D051379:Mice; D011233:Precipitin Tests; D051381:Rats; D011916:Rats, Inbred F344; D011920:Rats, Inbred WF; D012550:Schistosoma mansoni / Q000032:analysis / Q000276:immunology*; D012552:Schistosomiasis / Q000276:immunology*; D012967:Sodium Dodecyl Sulfate
D000947:Antigens, Helminth; D007106:Immune Sera; D012967:Sodium Dodecyl Sulfate