More than 1 billion people are at risk worldwide for developing schistosomiasis caused by one of five species of Schistosoma. Two species that cause the most human disease, Schistosoma japonicum and Schistosoma mansoni, infect the intestine and liver by similar processes, but differ in their geographically distribution. Neither are thought to be contained, and both have increased their global footprint to new regions of the world. In addition to infecting humans, S. japonicum infects cattle and water buffalo, which are greatly needed for meat, milk, as well as for farming. Infection of livestock results in significant financial losses to farmers and is also considered to be a key factor in human transmission. There currently is no vaccine for S. japonicum in animals or humans, and very few prospective vaccines are under consideration. The only cure for schistosomiasis is an anti-parasitic drug, praziquantel, and there is inherent fear that these parasites will eventually develop drug resistance. We are proposing to develop a vaccine for S. japonicum based on a similar vaccine we have developed for S. mansoni called SchistoShield. SchistoShield, which is based on a single parasitic protein called Sm-p80, is the only vaccine currently under evaluation that impacts nearly all phases of the Schistosoma life cycle. We have recently isolated the identical protein in S. japonicum, called Sj-p80, that it is nearly identical to Sm-p80. Because Sm-p80 provides partial protection against S. japonicum infection in mice, we predict that Sj-p80 will provide superior protection against this disease. The goals of this proposal are: 1) produce Sj-p80 protein for immunization of mice; 2) demonstrate in mice that Sj-p80 protein exhibits superior protection against S. japonicum compared to Sm-p80, and 3) develop a low cost, minimally purified version of the Sj-p80 that would be a suitable veterinary vaccine while still providing complete protection. Successful completion of this grant will validate Sj-p80 as a viable veterinary vaccine against Asiatic schistosomiasis. If the antigen holds promise in protection against Asian schistosomiasis, the proposed activities will allow us to move towards testing in cattle and commercialization of the veterinary vaccine in endemic countries as well as towards future human clinical trials.
Asiatic schistosomiasis caused by the blood fluke S. japonicum is a debilitating disease of humans and animals in several Asiatic countries. By producing a vaccine for this disease as proposed in this application, we will have a significant impact on global health.