construction of an adenovirus vaccine expressing the crossreactive antigen ama1 for neospora caninum and toxoplasma gondii and its immune response in an animal model

Background: we aimed to construct an adenovirus expressing a cross-reactive fragment of the apical membrane antigen 1 (ama1) antigen and evaluated the concomitant immune response in babl/c mice, allowing protection against n. caninum and t. gondii infection. methods: the study was conducted in agricultural college of yanbian university, yanji, jilin, china in 2015-2016. primers were designed using the ama1 gene sequences of n. caninum (ab265823.1) and t. gondii (af010264.1). after linearization of the plasmid adv4-ncama1 and the framework plasmid pacad5, a total of 293t cells were cotransfected and ad5-ncama1 recombinant adenovirus were packed. balb/c mice were inoculated. simultaneously serum igg antibody levels and ifn-γand il-4 cytokine levels were determined by elisa. after immunization three times in two weeks, each group of babl/c mice were divided into two groups, respectively given intraperitoneal inoculation by the neospora tachyzoite and toxoplasma tachyzoite. then we observed the clinical symptoms and statistical survival rate of mice. results: the level of igg in babl/c mice immunized with ad5-ncama1 was significantly increased when compared with that of pvax1-ncama1 and pbs groups (p<0.01). at the same time, the cytokine levels of ifn-γ and il-4 were also higher in the ad4-ncama1 group than in the control groups (p<0.01). moreover, babl/c mice immunized with ad5-ncama1, pvax1-ncama1, and pbs showed survival rates of 75%, 45% and 20% after n. caninum infection, and 45%, 10% and 0% after t. gondii infection, respectively. conclusion: the adenovirus vaccinead5-ncama1 could provide protective immunity against n. caninum and t. gondii infection.