STAGE-SPECIFIC SURFACE-ANTIGENS OF THE CATTLE LUNGWORM DICTYOCAULUS-VIVIPARUS

Immunofluorescence on live Dictyocaulus viviparus parasites revealed a significant antibody response by vaccinated and patently infected bov ine hosts to the sheath of infective larvae (L3), a structure which is generally thought to be shed from the parasite surface prior to invas ion of host tissue. In contrast, surface-exposed antigens of the adult , egg and pulmonary L1 stages were recognized only by serum antibody f rom calves exposed to a patent lungworm infection. Radioiodination of sheathed L3 identified a restricted set of components while a more com plex pattern of labelled material was observed with adult parasites. M any more components of adult worms were labelled by the Bolton-Hunter than by the Iodogen reagent, probably reflecting the more penetrative labelling propensities of the former. Stage-specificity of surface-ass ociated antigens of adult parasites was demonstrated by their immunopr ecipitation by antibody from patently-infected, but not from vaccinate d, calves. There was no in vitro release of the major iodinatable surf ace-associated antigens of adult parasites nor any binding of antibody raised against adult excretory-secretory (ES) products to the surface of living adult worms, suggesting that surface components do not cont ribute to adult ES products in this species. Antibody responses to the surface of adults, L1 and eggs were specific to patently-infected ani mals and may provide a useful indicator of exposure to patent infectio n.