Molecular characterization of Schistosoma mansoni tegument annexins and comparative analysis of antibody responses following parasite infection.
Schistosomes are parasitic blood flukes that infect approximately 250 million people worldwide. The disease known as schistosomiasis, is the second most significant tropical parasitic disease after malaria. Praziquantel is the only effective drug currently licensed for schistosomiasis and there are concerns about resistance to the drug. There has been much effort to develop vaccines against schistosomiasis to produce long-term protection in endemic regions. Surface-associated proteins, and in particular, those expressed in the body wall, or tegument, have been proposed as potential vaccine targets. Of these, annexins are thought to be of integral importance for the stability of this apical membrane system. Here, we present the structural and immunobiochemical characterization of four homologous annexins namely annexin B30, annexin B5a, annexin B7a and annexin B5b from S. mansoni. Bioinformatics analysis showed that there was no signal peptide predicted for any annexin in this study. Further analysis showed that each of all four annexin protein possesses a primary structure consisting of a short but variable N-terminal region and a long C-terminal core containing four homologous annexin repeats (I-IV), which contain five alpha-helices. The life cycle expression profile of each annexin was assessed using quantitative PCR. The results showed that the overall transcript levels of the each of four homologous annexins were relatively low in the egg stage, but increased gradually after the transition of cercariae (the invasive schistosome larvae) to schistosomula (the post-invasive larvae). Circular dichroism (CD) demonstrated that rAnnexin B30, rAnnexin B5a and rAnnexin 7a were folded, showing a secondary structure content rich in alpha-helices. The membrane binding affinity was enhanced when rAnnexin B30, rAnnexin B5a and rAnnexin 7a was incubated in the presence of Ca2+. All annexin members evaluated in this study were immunolocalized to the tegument, with immunoreactivity also occurring in cells and in muscle of adult parasites. All four recombinant annexins were immunoreactive and they were recognized by the sera of mice infected with S. mansoni. In conclusion, the overall results present the molecular characterization of annexin B30, annexin B5a, annexin B7a and annexin B5b from S. mansoni in host-parasite interactions and strongly suggest that the molecules could be useful candidates for vaccine or diagnostic development.
['Leow|Chiuan Yee|CY|', 'Willis|Charlene|C|', 'Leow|Chiuan Herng|CH|', 'Hofmann|Andreas|A|', 'Jones|Malcolm|M|']
D000595:Amino Acid Sequence D000818:Animals D017302:Annexins D000909:Antibodies, Helminth D000947:Antigens, Helminth D001483:Base Sequence D002942:Circular Dichroism D019295:Computational Biology D004195:Disease Models, Animal D005260:Female D015801:Helminth Proteins D006801:Humans D008297:Male D051379:Mice D016253:Microscopy, Immunoelectron D000072756:Protein Conformation, alpha-Helical D011994:Recombinant Proteins D012550:Schistosoma mansoni D012555:Schistosomiasis mansoni D013329:Structure-Activity Relationship
Schistosoma mansoni Annexin Schistosomiasis Immunolocalization Immunoreactivity Parasite–host interactions