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A chloroplast‐derived T oxoplasma gondii GRA 4 antigen used as an oral vaccine protects against toxoplasmosis in mice

2012; Wiley; Volume: 10; Issue: 9 Linguagem: Inglês

10.1111/pbi.12001

1467-7652

María del L. Yácono, Inmaculada Farrán, Melina Laguía Becher, Valeria A. Sander, Vanesa R. Sánchez, Valentina Martín, Jon Veramendi, Marina Clemente,

Herpesvirus Infections and Treatments

Summary The parasitic protozoan T oxoplasma gondii, the causal agent of toxoplasmosis, can infect most mammals and birds. In human medicine, T . gondii can cause complications in pregnant women and immunodeficient individuals, while in veterinary medicine, T . gondii infection has economic importance due to abortion and neonatal loss in livestock. Thus, the development of an effective anti‐ T oxoplasma vaccine would be of great value. In this study, we analysed the expression of T . gondii GRA 4 antigen by chloroplast transformation (chl GRA 4) in tobacco plants and evaluated the humoral and cellular responses and the grade of protection after oral administration of chl GRA 4 in a murine model. The W estern blot analysis revealed a specific 34‐ kD a band mainly present in the insoluble fractions. The chl GRA 4 accumulation levels were approximately 6 μg/g of fresh weight (equivalent to 0.2% of total protein). Oral immunization with chl GRA 4 resulted in a decrease of 59% in the brain cyst load of mice compared to control mice. Chl GRA 4 immunization elicited both a mucosal immune response characterized by the production of specific I g A , and IFN ‐γ, IL ‐4 and IL ‐10 secretion by mesenteric lymph node cells, and a systemic response in terms of GRA 4‐specific serum antibodies and secretion of IFN ‐γ, IL ‐4 and IL ‐10 by splenocytes. Our results indicate that oral administration of chl GRA 4 promotes the elicitation of both mucosal and systemic balanced T h1/ T h2 responses that control T oxoplasma infection, reducing parasite loads.