IMMUNIZATION OF MICE WITH RECOMBINANT SJC26GST INDUCES A PRONOUNCED ANTI-FECUNDITY EFFECT AFTER EXPERIMENTAL-INFECTION WITH CHINESE SCHISTOSOMA-JAPONICUM

We report the cloning, by polymerase chain reaction (PCR), of a cDNA e ncoding a Schistosoma japonicum (Chinese) 26 kDa glufathione-S-tranfer ase (GST) (Sjc26GST), expression of the cDNA, affinity purification of the recombinant GST and its vaccine efficacy in outbred NIH mice usin g Freund's as adjuvant. The most striking feature of the vaccination e xperiments was the pronounced reduction in the number of eggs in the l ivers and spleens of immunized mice. A relatively low but significant level of protection in terms of reduced worm viability against challen ge infection was also observed Further, the level of anti-Sjc26GST ant ibody in immunized mice was significantly higher than in control mice at week 6 post-challenge infection. These results closely mirror the p rotection conferred by immunization of animals with the 28 kDa GST of S. mansoni (Sm28) where a reduction in worm viability, worm fecundity and egg-hatching ability have been reported following challenge with S . mansoni. In terms of developing a vaccine against schistosomiasis ja ponica, immunization with Sjc26GST can provide two complementary goals in human or animal populations-some reduction in worm burden followin g exposure to infection or reinfection, and an anti-disease effect thr ough reduction of pathology by a decrease in worm fecundity, with this direct effect also affecting the transmission of S. japonicum.