<p>This invention is a process for the manufacture of a plant viral capsid to be used for the targeted delivery of therapeutics to diseased cells. The process uses a plant virus as the starting material. The choice of the plant virus overcomes a problem in the manufacture of a uniform starting material. The final product has an advantage over other plant virus-based delivery systems in that the plant virus selected has a natural structure that is resistant to breakdown during the delivery process. This system takes advantage of the reversible divalent cation switch that this capsid employs to assemble and disassemble.</p>