The fusion of Toxoplasma gondii SAG1 vaccine candidate to Leishmania infantum heat shock protein 83-kDa improves expression levels in tobacco chloroplasts

ALBARRACÍN, RM; LAGUÍA BECHER, M; FARRAN, I; SANDER VA; YÁCONO, ML; CORIGLIANO, M; PARIANI, S; SANCHEZ-LOPEZ, EDWIN; VERAMENDI, J; CLEMENTE, M

Biotechnology Journal

Weinheim : Wiley-VCH Verlag, c2006

Año: 2015 vol. 20 p. 749 - 759

1860-6768

Chloroplast transformation technology has emerged as an alternative platform offering many advantages over nuclear transformation. SAG1 is the main surface antigen of the intracellular parasite Toxoplasma gondii and a promising candidate to produce an anti-T. gondii vaccine. In the present study, we investigate the expression of SAG1 using chloroplast transformation technology in tobacco plants. The relative amount of SAG1 protein accumulated in transplastomic plants was approximately 0.1-0.2 µg per gram of fresh weight (FW). In addition, we expressed the 90-kDa heat shock protein of Leishmania infantum (LiHsp83) to function as a carrier for SAG1 antigen in order to improve its expression in transplastomic plants. Fusion of SAG1 to LiHsp83 significantly increased the level of SAG1 accumulation in tobacco chloroplasts (by up to 500-fold). The relative amount of chLiHsp83-SAG1 fusion protein accumulated in transplastomic plants was up to approximately 100 µg per gram of FW (2.5 % of total protein), the majority of which was observed in the soluble protein fraction. Three human seropositive samples reacted with SAG1 expressed in transplastomic chLiHsp83-SAG1 plants. Oral immunization with chLiHsp83-SAG1 elicited an important reduction of the cyst burden when compared to control that correlated with an increased SAG1-specific antibodies. We propose the fusion of foreign proteins to LiHsp83 as a novel strategy to increase the expression level of the recombinant proteins using chloroplast transformation technology, thus addressing one of the current challenges for this approach in antigen protein production.