Abstract
BackgroundSchistosomiasis is a water-borne disease afflicting over 261 million people in many areas of the developing countries with high morbidity and mortality. The control relies mainly on treatment with praziquantel. Fatty acid binding proteins (FABP) have demonstrated high levels of immune-protection against trematode infections. This study reports the immunoprotection induced by cross-reacting Fasciola hepatica FABP, native (nFh12) and recombinantly expressed using two different expression systems Escherichia coli (rFh15) and baculovirus (rFh15b) against Schistosoma mansoni infection.MethodsBALB/c mice were vaccinated with native nFh12 or recombinant rFh15 and rFh15 FABP from F. hepatica formulated in adjuvant adaptation (ADAD) system with natural or chemical synthesised immunomodulators (PAL and AA0029) and then challenged with 150 cercariae of S. mansoni. Parasite burden, hepatic lesions and antibody response were studied in vaccination trials. Furthermore differences between rFh15 and rFh15b immunological responses (cytokine production, splenocyte population and antibody levels) were studied.ResultsVaccination with nFh12 induced significant reductions in worm burden (83 %), eggs in tissues (82–92 %) and hepatic lesions (85 %) compared to infected controls using PAL. Vaccination with rFh15 showed lower total worm burden (56–64 %), eggs in the liver (21–61 %), eggs in the gut (30–77 %) and hepatic damage (67–69 %) using PAL and AA0029 as immunomodulators. In contrast, mice vaccinated with rFh15b showed only reductions in eggs trapped in the liver and intestine (53 and 60 %, respectively), and hepatic lesions (45 %). We observed a significant rise in TNFα, IL-6, IL-2, IL-4 and high antibody response (IgG, IgG1, IgG2a, IgM and IgE) in mice immunised with either rFh15 or rFh15b. Moreover, mice immunised with rFh15b showed an increase in IFNγ and a decrease in B220 cells compared to untreated mice, and less production of IgG1 and IgM than in mice immunised by rFh15.ConclusionsHigher level of protection is obtained by using Fasciola hepatica-derived FABP protein against Schistosoma mansoni infection. Native FABP is more effective than both recombinant systems. It could be due to post-translational modifications or FABP isoform or changes in the recombinant proteins.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1500-y) contains supplementary material, which is available to authorized users.
Highlights
Schistosomiasis is a water-borne disease afflicting over 261 million people in many areas of the developing countries with high morbidity and mortality
The aim of this study is to examine the immunoprophylactic properties of three Fatty acid binding proteins (FABP) from F. hepatica using the adjuvant adaptation (ADAD) vaccination system against S. mansoni infection in BALB/c mice
We used a baculovirus expression vector system that improves the production of recombinant proteins compared to the classical expression systems based on the use of bacteria or yeasts, which retains recombinant proteins native configuration along the production and purification steps to produce a F. hepatica-derived FABP protein (Fig. 1a and 1b)
Summary
Schistosomiasis is a water-borne disease afflicting over 261 million people in many areas of the developing countries with high morbidity and mortality. The control relies mainly on treatment with praziquantel. Fatty acid binding proteins (FABP) have demonstrated high levels of immune-protection against trematode infections. The main strategy against schistosomiasis involves the use of praziquantel to reduce worm burden and morbidity due to its high efficacy, affordable cost, operational convenience and limited side effects [2]. The basis of vaccine use against schistosomes is demonstrated by the partial resistance developed against natural infection and the high protection induced by irradiated cercariae reaching worm reductions of 41–75 % depending on the total number of immunising parasites [8]
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