| Schistosomiasis is a serious threat to human health that afflicts approximately 200 million people living in the endemic areas of 76 developing countries. The schistosome tegument surface constitutes the host-parasite interface and interplay with the host. Therefore to identify proteins that putatively expressed on the tegument holds the key to understand the mechanism of immune evasion and modulation, nutrition uptaking and so on, and help to discover new intervention targets for development of novel control strategies. Schistosomes express a family of tetraspanins on their tegument. Members of TSP family of Schistosoma mansoni have been regarded as potential protective antigens, especially tetraspanin-2 (TSP-2) which induced as high as-60% protection in S. mansoni. But its homolog in S. japonicum is variable and involved in immune evasion, which implicates that disproportionation occurred between the two spieces during evolution. Therefore, it is important to further investigate TSPs of S. japonicum, in order to identify new targets for vaccine candidates and drugs.In this work, we identified 29 TSP members of Schistosoma japonicum using bioinformatics method. Besides Sj-tsp-2 and Sj-25, we identified 3 more TSP members were variable, and 2 Sj-tsp gene were alternative spliced. Those data implicated that these 7 tegument proteins may be involved in immune evasion and highly polymorphic of these molecules must affect their potential as vaccine candidates.Quantitative real time PCR analysis revealed that Sj-tsp genes were transcribed in cercariae, schistosomula, separated adult worms, and eggs at diverse levels. The newly transformed schistosomulum stage is the most susceptible to the immune response and is a target for vaccine development and rational drug design. Thus we pay more attention to the expression of TSP genes at this stage. Twelve Sj-tsp genes were highly expressed in schistosomula, eight of which were up-regulated during the developmeant from cercariae to schistosomulum. It indicates that these eight molecules play roles in adapting host environment after invasion. Among them, Sj-tsp-2 and Sj25 were variable, while Sj-tsp-7 was alternative spliced, suggest that they were not only functions in host but also in evasion strategy. We suppress expression of Sj-tsp genes that were conserved and highly expressed in schistosomula using RNAi in vitro, to investigate the thire potential functions. Four Sj-tsp genes suppression levels were>80%, nine Sj-tsp genes suppression levels were 40%-60%. The tegument integrity of Sj-tsp-suppressed parasites was not affected and there was no significant difference in the survival rate between the siRNA-treated and control groups. It implies that Sj-tsp may play roles in host-parasite interplay in vivo, so we can't detect the suppression affect on schistosomula in vitro.In summary, based on the molecular characterization of TSPs including conservsion, transcription levels,,and the number of cysteine residues in the LEL, we preliminary screen 5 Sj-tsp genes with potential to be antigen candidates, providing a foundation for further protection study of Sj-tsp.Malaria is one of the most infectious diseases to human health in the world. Plasmodium falciparum parasite causes about 300-500 million cases and about 1-3 million people die as a result. Most of these deaths occur in children under the age of 5 year in sub-Saharan Africa. The emergence and spread of drug-resistant parasites and insecticide-resistant Anopheles mosquito vectors make prevention and treatment of malaria a big problem. Thus, a safe and effective malaria vaccine would prevent severe disease and death in African children and other at-risk populations.In the previous work, we have constructed polyepitope libraries with epitope shuffling technology, screened positive clones with high antigenicity by dot blot and obtained a positive clone named VR312 (renamed as M.RCAg-1 later) which could induce cross-protection in mice and inhibitory antibodies against Plasmodium falicparum in rabbits; another clone D10 also could induce inhibitory antibodies against Plasmodium falicparum in rabbits.In this study, we use optimized DNA vectors, in vivo electroporation and 4-1BBL or Cimetidine as molecular adjuvants to improve efficacy of DNA vaccination. DNA delivery using electroporation led to high levels of IgG titers with low DNA dose.pVAX1 expression vectors is more effective than VR1012 expression vectors. But either 4-1BBL or Cimetidine can enhance M.RCAg-1 and D10 DNA vaccine antibody titers compared to controls. |
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