Studies The 23KD Antigen Gene Of Schistosoma Japonicum (Chinese Strain)

Studies on the 23KD antigen gene of Schistosoma japonicum( Chinese strain )ABSTRACTSchistosomiasis japonicum is still a serious public health problem in China. Developing an effective vaccine and establishing a more sensitive diagnostic technique is required for the schistosomiasis controlling program in China. The 23KD integral membrane protein of schistosome is an antigen of some interests in terms of both anti-parasite vaccination and immuno-diagnosis. The studies focused on the cloning and expressing of the DNA fragment that encodes the large hydrophilic domain of Sj23 (LHD-SJ23) as well as that of the full length SJ23. The purified LHD-Sj23/pGEX fusion protein was employed to vaccinate the animals, and 57.8% ~ 70.3 %( PO.01) and 66.1% (PO.0001) worm reduction were obtained from the vaccinated mice and sheep respectively when comparing with that of the blank control animals. Immuno-mechanism study revealed that high levels of specific IgG (IgGl, IgG2a, IgG2b and IgG3) may play an important role for the protective effect of the vaccinating mice. The immunogenicity and antigenicity studies show that the recombinant antigen LHD-Sj23/pGEX was recognized by sera from the schistosomiasis chronic infected mice, the irradiated Schistosoma japonicum cercaria vaccinated mice and rats, irradiated Schistosoma mansoni cercaria vaccinated mice, and Schistosome japonicum adult worm membrane antigens or GST antigen vaccinated mice.For finding the possible way to improve the protective efficacy induced by the recombinant antigen, rats and sheep were co-injected with LHD-Sj23/pGEX and SjFABP, another important vaccine candidate for schistosomiasis, or low dose anti-schistosomiasis drug praziquental. The results showed that 47.28%( pO.Ol) worm reduction was obtained in the rats co-injected with LHD-Sj23/pGEX and SjFABP, significantly higher than those injected with LHD-Sj23/pGEX (32.14%) or SjFABP (31.85%) only. In another experiment, 58.09% worm reduction (p<0.005) was got in the sheep co-injected with LHD-Sj23/pGEX and low dose praziquental, significantly higher than those injected with LHD-Sj23/pGEX (22.45%) or praziquental (42.60%) only.ABSTRACTThe recombinant antigen LHD-Sj23/pGEX was employed as diagnostic antigen for detecting bovine and sheep schistosomiasis by ELISA. 94.0% (79/84), 85.5%(53/62) and 86.04%(1 11/129) positive coincidence rates, 82.7%(81/98), 95.1%(77/81) and 100%(91/91) negative coincidence rates were obtained from yellow cattle, water buffaloes and sheep respectively. The similar results were got by using SWAP, SEA as diagnosing antigen comparing with that of recombinant LHD-Sj23/pGEX. No cross-reaction was found in 24 sheep Trypanosomosis. The study revealed that the SJ23 is an important vaccine candidate and a good diagnostic antigen for schistosomiasis japonicum.