Efficient expression of a Toxoplasma gondii dense granule Gra4 antigen in tobacco leaves.

A His-tagged truncated version of Toxoplasma gondii dense granule 4 protein (Gra4(163-345)) was transiently expressed in tobacco leaves. Two genetic constructions were used to accomplish this goal. In one of them, based in a Potato virus X (PVX) amplicon, the sequence encoding His-Gra4(163-345) was placed under control of an additional PVX coat protein subgenomic promoter. In the other, the same sequence was fused to an apoplastic transport signal and placed under the direction of the cauliflower mosaic virus 35S promoter. His-Gra4(163-345) accumulation in agroinfiltrated tobacco leaves was estimated by Western blot analysis using mouse anti-Gra4 antibody and a seropositive human serum. Here, we demonstrated the feasibility of producing a Gra4 antigen using transient expression methods in plants.