Evaluation Of Vaccine Candidates Rsjlap And Rsjfbpa In The Immunoprotection Of Mice Infected With Schistosoma Japonicum

Objective: To explore the immune protective effects of two recombinant antigens of rSjLAP and rSjFBPA based on the 2-DE oriented screening of the serum proteomics with adjuvant in BALB/c mice. The immune enhancing effect of Freund's adjuvant and Nano-C60 adjuvant was compared for assessment of Nano-C60 in development of Schistosoma japonicum molecular vaccine.Methods: RSjLAP and rSjFBPA induced and expressed from the transformed bacteria were purified with affinity chromatography (His-Bind Purification Kit). The 6-week-old BALB/c mice were randomly divided into seven groups, 6 mice each. All mice, except the control, were immunized three times at 2-week's intervals by subcutaneous multi-point injection as the dosage of rSjLAP or rSjFBPA 100μg / time / mouse. Seven groups of mice were immunized as follows:①control: injected subcutaneously with equal volume of saline,②rSjLAP + Freund's adjuvant,③rSjFBPA + Freund's adjuvant,④rSjLAP + rSjFBPA + Freund's adjuvant,⑤rSjLAP + Nano-C60 adjuvant,⑥rSjFBPA + Nano-C60 adjuvant,⑦rSjLAP + rSjFBPA + Nano-C60 adjuvant. After 5 weeks, the mice sera were collected and both Th1 cytokines (IFN-γ) and Th2 cytokines (IL-4) were detected with ELISA. The BALB/c mice were infected with schistosome cercariae , 30±2 cercariae / mouse. After 6 weeks, the mice were sacrificed under anesthesia for calculating the reduction rates of worm burden and hepatic tissue eggs.Results: The worm reduction rates in groups 2,3, and 4 were found to be 35.5% (P <0.05),33.0% (P <0.05),and 38.1% (P<0.05), respectively;the worm reduction rates of groups 5, 6 and 7 were 43.1% (P <0.05);39.1% (P <0.05), and 45.2% (P <0.05), respectively; the eggs reduction rates of groups 2,3 and 4 were 40.2% (P <0.05), 42.6% (P <0.05), and 48.9% (P <0.05);the eggs reduction rates of groups 5,6, and 7 were found to be 41.6% (P <0.05), 45.4% (P<0.05 ), and 46.9% (P <0.05), respectively. The IFN-γlevels(pg/ml) of the control group, rSjLAP + Freund's adjuvant group, rSjFBPA + Freund's adjuvant group were 20.4, 20.1,and 19.6, respectively. The IL-4 level(spg/ml) were 192.0,382.0,518.0, respectively.The results showed that the rSjLAP and rSjFBPA and both adjuvants were able to significantly improve the protective immunity in mice with infection of S. japonicum.Conclusions: The BALB/c mice, which had been immunized with rSjLAP and rSjFBPA with Freud's adjuvant or Nano-C60 adjuvant showed a certain immune protection . Only slight difference was noted between Freud's and Nano-C60 adjuvents although both of them might give rise to a relative immune enhancement. Our results indicated that both rSjLAP and rSjFBPA might be molecular candidates for the development of vaccine in schistosomiasis. The IFN-γlevels of all experimental groups did not show a significant change whereas the IL-4 levels changed dramatically, suggesting that the predominant Th2 cell response exists in mice infected with S. japonicum following the antigen vaccination.