An inexpensive, plant-derived, dual vaccine for rotavirus and cholera

Rotavirus is the leading cause of severe infantile diarrhea worldwide. Most related deaths occur in infants from developing countries. Current vaccines are expensive and not readily available throughout the world. Chloroplast transformation technology can be utilized to generate genetically modified plants that produce large quantities of therapeutic proteins and vaccine antigens within their leaves. Plants that are used as bioreactors for vaccine antigens are economically advantageous because they eliminate the need for purification steps and are cheaper to transport. A genetically modified crop could potentially be grown near an endemic area and harvested as needed. There are many influencing factors for transgene expression levels within plant leaves that must be taken into account prior to their harvest. In this work, we seek to determine the optimal expression of CTB-NSP4 in two different cultivars of tobacco plant that have been previously generated by the Daniell lab. The fusion protein, CTBNSP4, is hoped to confer resistance to both rotavirus and cholera. We will determine how the expression of the protein is affected by different variables such as the lighting conditions during harvest and the relative age of leaf at the time of harvest. This knowledge can be used to raise the productivity of the genetically modified plants, further decreasing the cost. Additionally, as unprocessed leaf cannot be used directly for oral delivery due to an unknown concentration of the vaccine antigen, quantification is an important barrier to overcome. Low cost vaccines can be prepared after optimization of dosage and stability. This project seeks to substantiate and quantify genetically modified tobacco plants producing the rotavirus and cholera vaccine antigens