EN
Exsheathed infective larvae, fourth stage larvae and adult A. ceylanicum were surface labelled with biotin. The surface proteins were extracted sequentially with Tris buffer saline, sodium dodecyl sulphate and 2-mercaptoethanol then analysed by SDS-PAGE and Western blotting. It was found that A. ceylanicum expresses different surface proteins on each of its three parasitic developmental stages and that these proteins vary in their immunogenicity to the host. Most of the proteins on the surface of exsheathed infective larvae were TBS-soluble and some of these elicited serum antibody responses in infected hamsters. The antibody response to surface antigens recognised by post-primary infection sera was not boosted on reinfection but challenge exposure to larvae induced antibody reactivity to 3 additional L3 polypeptides. The most intense reactivity of post-infection sera was evident with SDS-soluble surface proteins of fourth stage larvae. The post-infection sera showed weaker recognition of the surface antigens of adult worms compared to both larval stages, although the same sera were intensely reactive with adult worm somatic proteins.