Malarial Epitopes Expressed on the Surface of Recombinant Tobacco Mosaic Virus

Using malaria as a model disease, we engineered the surface of tobacco mosaic tobamovirus (TMV) for presentation of selected epitopes to the mammalian immune system. The TMV coat protein is a well-characterized and abundant self-assembling polymer previously shown to be a highly immunogenic carrier. Selected B-cell epitopes were either inserted into the surface loop region of the TMV coat protein or fused to the C terminus using the leaky stop signal derived from the replicase protein reading frame. Tobacco plants systemically infected with each of these constructs contained high titers of genetically stable recombinant virus, enabling purification of the chimeric particles in high yield. Symptoms induced in tobacco ranged from a normal mosaic pattern similar to that induced by the parental U1 strain to a unique bright yellow mosaic. As measured by quantitative ELISA against synthetic peptide standards, wild type TMV coat protein and fusion protein synthesized by the leaky stop mechanism coassembled into virus particles at the predicted ratio of approximately 20:1. Recombinant plant viruses have the potential to meet the need for scalable and cost effective production of subunit vaccines that can be easily stored and administered.