ORAL VACCINATION OF MICE WITH RECOMBINANT SCHISTOSOMA-JAPONICUM PROTEINS INDUCES SPECIFIC ANTIPARASITE ANTIBODIES AND DAMAGE TO ADULT WORMSAFTER A CHALLENGE INFECTION

Mucosal immunisation by the oral route represents a cheap and simple m ethod for delivering protective antigens to a host against gastrointes tinal and respiratory pathogens. In the case of schistosome (bloodfluk e) worms, 2 life-cycle stages may be exposed to the host's mucosa; the larval schistosomulum is exposed to the respiratory mucosa and, depen ding on the species, the egg may come into contact with the intestinal or urinogenital mucosa. Both IgA and some isotypes of Ige hare been i mplicated in protective immunity against schistosomiasis in humans and in experimental animal models. We have used a novel approach to deter mine whether schistosome-specific antibodies and protective immunity c ould he generated in mice by oral administration of bacterial lysates containing recombinant Schistosoma japonicum proteins. The mice produc ed specific antibodies to paramyosin and GST26, 2 important vaccine ca ndidates for schistosomiasis, but there was no significant reduction i n worm burdens in groups of mice immunised with either protein, Signif icantly, however, transmission electron microscopy revealed damage to the teguments of adult female and male S. japonicum worms obtained fro m mice vaccinated with recombinant paramyosin; there was also extensiv e damage to the tegument of male worms recovered from mice vaccinated with recombinant GST26. Our observations that oral vaccination with ba cterial lysates containing recombinant proteins induced particular cla sses and subclasses of circulating antibodies with resultant damage to the surface of adult worms may have important implications far the fu ture development of oral vaccines against a systemic infection such as schistosomiasis. (C) 1997 Australian Society for Parasitology. Publis hed by Elsevier Science Ltd.