Protective Function Of SjDLC,SjCB2 DNA Vaccine And IFN-? In Schistosoma Japonicum Infection

[Objective] To construct Schistosoma japonicum DNA vaccine and IFN–?.Then the immunoprotective efficacy of combined vaccine pcDNA3.1(-)/SjDLC+pcDNA3.1(+)/SjCB2, and IFN–? were estimated in the BALB/c mice infected with Schistosoma japonicum.[Methods] To construct pcDNA3.1(-)/SjDLC,pcDNA3.1(+)/m IFN-? recombinant plasmids by PCR, identified by restriction enzyme digestion and DNA sequencing.There combinant vector pcDNA3.1(-)/SjDLC, pcDNA3.1(+)/m IFN-? were transfected into Hela cells, these expressed protein were identified by Western blot.BALB/c mice were divided into 7 groups,PBS(A group)?pcDNA3.1(+)(B group)?pcDNA3.1(+)/ mIFN-?(C group)?pcDNA3.1(+)/SjCB2(D group)?pcDNA3.1(-)/SjDLC(E group)?pcDNA3.1(+)/ SjCB2+pcDNA3.1(-)/SjDLC(F group) ? pcDNA3.1(+)/SjCB2+pcDNA3.1(-)/SjDLC+pcDNA3.1(+)/mIFN-?(G group). According to the groups, these plasmids injected into BALB /c mice at 2-week interval for 3 times, and each mouse was challenge infected with cercariaes of Schistosomajaponicum after 2 weeks since final inoculation. The gene of SjCB2,SjDLC, IFN-? in quadriceps femoris were identified by PCR. The expression of SjCB2, SjDLC, IFN-? in quadriceps femoris were observed with immunohistochemistry. At the same time, each mouse was challenge infected with cercariaes of Schistosoma japonicum. The blood, spleen and liver tissue of experimental mice were collected and detected at different points(0w?2w?4w?6w?8w?10w) in time. HE and Masson staining were used to observe the pathological changes of liver tissue; FCM was used to analyze the percentage of Th1?Th2cells of CD4+T cells in liver and spleen tissue. IFN-?, IL-4, IgG and IgE level among different groups and its dynamic change were detected by ELISA. After 6w of infection, the eggs of every mice liver were counted respectively, and the quantity of adult worm burden of BALB/c mice were counted also. [Results] The recombinant plasmids pcDNA3.1(-)/SjDLC, pcDNA3.1(+)/m IFN-? were constructed successfully. SjDLC, IFN-? were successfully expressed in HeLa cells by western blotting. The gene of SjCB2, SjDLC, IFN-? in quadriceps femoris could be sucessfully ampified by PCR. The immunohistochemistry analysis showed that the SjCB2,SjDLC, IFN-?were expressed in the local tissue. HE and Masson staining show that at the stage of 6w~10w, PBS and pcDNA3.1(+) groups had the most worst pathological changes, and with the development of the times. TheC, D, E, F and G groups were significantly relieved the pathological changes in same times. In those groups, G group was significantly lower than the other groups. FCM results showed that the proportion of Th1 cells in the liver and spleen reached peak value at 4w, the Th1 cell proliferation significantly higher than 0w, P<0.05.The C, D, E, F and G groups were significantly higher than A and B groups. In those groups,G group was the supremacy. At the stage of 6w~10w, the Th1 cell proliferation of all groups had decreased. But the C, D, E, F and G groups significantly higher than A and B groups, P<0.05. The proportion of Th2 cells in the liver and spleen at the stage of 6w~10w were significantly higher than 4w, P<0.05, the Th2 cell proliferation reached peak value at 8w. But the C, D, E, F and G groups were significantly lower than A and B groups, P <0.05. In those groups,G group was significantly the lowest. ELISA results showed that the mice serum IFN-? is the same as the proportion of Th1 cells. IL-4 is the same as the development of the proportion of Th2 cells. ELISA test results showed that the mice serum IgG reached maximum value at 6 w, the DNA vaccine groups were significantly higher than A and B groups, In those groups,G group was significantly the highest. Ig E reached peak at 8w, the D, E, F and G groups were significantly higher than A, B and C groups. In those groups,G/ F group was significantly the highest.The worm burden reduction rate and the reduction rate of liver egg inthe DNA vaccine groups were significantly higher than A and B groups(P<0.05). The worm burden reduction rate and the reduction rate of liver egg were 40.5% ? 55.7% in G group are the most strongest protective effect, P<0.05.[Conclusion] The DNA vaccine and IFN-?could induce immunity against S. japonicum infection. The combined vaccine and IFN-? could be induce the best immunity.