Protective immunity induced by peptides of AMA1,RON2 and RON4 containing T-and B-cell epitopes via an intranasal route against toxoplasmosis in mice

Background: toxoplasma gondii is a ubiquitous protozoan intracellular parasite,the causative agent of toxoplasmosis,and a worldwide zoonosis. apical membrane antigen-1 (ama1) and rhoptry neck protein (ron2,ron4) are involved in the invasion of t. gondii. methods: this study chemically synthesized peptides of tgama1,tgron2 and tgron4 that contained the t- and b-cell epitopes predicted by bioinformatics analysis. we evaluated the systemic response by proliferation,cytokine and antibody measurements as well as the mucosal response by examining the levels of antigen-specific secretory iga (siga) in the nasal,vesical and intestinal washes obtained from mice after nasal immunization with single (ama1,ron2,ron4) or mixtures of peptides (a1∈+∈r2,a1∈+∈r4,r2∈+∈r4,a1∈+∈r2∈+∈r4). we also assessed the parasite burdens in the liver and brain as well as the survival of mice challenged with a virulent strain. results: the results showed that the mice immunized with single or mixed peptides produced effective mucosal and systemic immune responses with a high level of specific antibody responses,a strong lymphoproliferative response and significant levels of gamma interferon (ifn-γ),interleukin-2 (il-2) and il-4 production. these mice also elicited partial protection against acute and chronic t. gondii infection. moreover,our study indicated that mixtures of peptides,especially the a1∈+∈r2 mixture,were more powerful and efficient than any other single peptides. conclusions: these results demonstrated that intranasal immunisation with peptides of ama1,ron2 and ron4 containing t- and b-cell epitopes can partly protect mice against toxoplasmosis,and a combination of peptides as a mucosal vaccine strategy is essential for future toxoplasma vaccine development. © 2015 zhang et al.; licensee biomed central.