Immunisation with Salmonella typhimurium-delivered glyceraldehyde-3-phosphate dehydrogenase protects mice against challenge infection with Echinococcus multilocularis eggs

Recombinant glyceraldehyde-3-phosphate dehydrogenase of the cestode parasit e Echinococcus multilocularis was expressed in Escherichia coli and in Salm onella typhimurium. The potential of different forms of the recombinant ant igen to protect BALB/c mice against oral challenge infections with E. multi locularis eggs was evaluated. Oral or intraperitoneal immunisation with liv e attenuated S. typhimurium as a carrier for recombinant glyceraldehyde-3-p hosphate dehydrogenase of the E. multilocularis resulted in significant pro tection, reducing the number of developing metacestodes up to 79.8%. The se ra of protected animals did not contain detectable amounts of antibody agai nst glyceraldehyde-3-phosphate dehydrogenase of E. multilocularis. By contr ast, although anti-glyceraldehyde-3-phosphate dehydrogenase of E. multilocu laris antibodies were detectable in the sera, immunisation with E. coli-exp ressed recombinant glutathione-S-transferase-fusion protein or with glycera ldehyde-3-phosphate dehydrogenase of E. multilocularis fused to a 6HIS-tag failed to protect the animals against oral challenge infections. These data emphasise that antigen delivery systems play a critical role in vaccinatio n and the induction of protective immunity against helminth parasites. (C) 2001 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.