Expression of Toxoplasma gondii antigens in tobacco leaves and evaluation of immuno response in mice

LAGUÍA BECHER M; KRAEMER M; MARTIN V; GOLDMAN A; CLEMENTE M

Carlos Paz, Cordoba

Congreso; SAIB; 2008

Sociedad Argentina de investigaciones bioquímicas

T. gondii Gra4163-345 and SAG178-322 were transiently expressed in tobacco leaves by agro-infiltration. Here, we explored different approaches to improve transgene expression in plants, like subcellular targeting and codon optimization. Gra4163-345 and SAG178-322 were targeted to the cytoplasm, endoplasmic reticulum (ER) or to the apoplastic space by adding different targeting signals. Both sequences were modified for plant codon optimization. The expression was confirmed by Western blot and the level of recombinant proteins in leaf extracts was estimated using the Gel Pro Analizer 4.0 program.. Gra4163-345 accumulation was increased when the protein was targeted to the apoplastic space, while SAG178-322 accumulation was improved when the protein was targeted to the ER. However, no difference in yields was observed for Gra4163-345 and SAG178-322 optimized versions. Finally, the C57/BL6 mice were immunized with SAG1, Gra4 or both -expressing leaf extracts and orally challenged with a nonlethal dose of the T. gondii. Mice vaccinated with SAG1, Gra4 or both showed significantly lower brain cyst burdens compared to those from the control group (SAG1 62%, GRA4 66%, SAG1+GRA4 59%). Our results showed that protective immunity could be established in mice injected with transgenic leaf extracts.