DEVELOPMENTALLY-REGULATED EXPRESSION OF A HAEMONCHUS-CONTORTUS SURFACE-ANTIGEN

All life cycle stages of Haemonchus contortus were screened with antib ody-secreting cell (ASC) probes generated from immune sheep 5 days aft er a challenge infection, An antigen with an approximate molecular wei ght of 70-90 kDa was found to be predominantly expressed in the 3rd-st age larvae, while a molecule with an approximate molecular weight of 2 8-31 kDa was recognised by the ASC-probes in the earlier developmental stages, Antisera generated against the purified 70-90 kDa molecule an d antibodies eluted from the 70-90 kDa region in the 3rd-stage larvae were found to react with the 28-31 kDa region in the 2nd-stage larvae. These results suggest that the 70-90 kDa antigen, previously identifi ed as a major 3rd-stage surface antigen, is synthesised as a lower mol ecular weight molecule in the earlier larval stages and assembled into a higher molecular weight complex through non-reducible covalent bond s. Copyright (C) 1996 Australian Society for Parasitology.