ORAL VACCINES: USE OF PLANTS FOR THE EXPRESSION OF THE MAIN SURFACE ANTIGEN 1 (SAG1) of Toxoplasma gondii

RADONIC, LAURA; LÓPEZ BILBAO, MARISA; SÁNCHEZ LÓPEZ, EDWIN F; SANDER, VALERIA A.; CORIGLIANO, MARIANA G.; CLEMENTE, MARINA

Quindio

Congreso; International Toxoplasma Congress (Toxo XV); 2019

There is an urgent need to develop vaccines against Toxoplasma gondii. Since the portal ofentry of T. gondii is the mucosa,Toxoplasma infection is an interesting model to study the optimization ofexpression systems based on plants and to assess the effectiveness of oralplant-made vaccines. Here, in order to improve the expression levels of vaccineantigen expressed in plants, we evaluated the role of plant Hsp90s as carrierof the SAG1 antigen. We assayed stable transformation system of lettuce plants andtransient expression of tobacco leaves by agroinfiltration to test theperformance of four different constructs carrying mature SAG1 protein (SAG1m)or a B- and T-cell epitopes of SAG1 peptide fused to Nicotiana benthamiana Hsp90 (NbHsp90.3) or Arabidopsis thaliana Hsp90 (AtHsp81.2). The agroinfiltration withAtHsp81.2-SAG1HC construct produced the highest level of SAG1 expression being theAtHsp81.2-SAG1HC protein accumulation60-fold higher than AtHsp81.2-SAG1m (120μg of AtHsp81.2-SAG1HC vs. 2 μg of AtHsp81.2-SAG1m per gram of fresh weight).On the other hand, SAG1myields in transgenic lettuce plants expressing AtHsp81.2-SAG1m orNbHsp90.3-SAG1m ranged from 35 to 45 μg per g of lyophilized leaves. Finally, atotal of 5 positive human serum samples were able to react with the recombinantfusion proteins suggesting that the SAG1 versions fused to plant Hsp90s can berecognized by antibodies from Toxoplasma-infected humans. Our results suggestthat plant Hsp90 improves the recombinant protein yields in plants and have thepotential to elicit immune responses in immunization protocols.