Plants have been extensively investigated for producing human vaccines. However, due to remaining challenges, particularly in the area of upstream and downstream processing, there are still no licensed plant-produced human vaccine products on the market. This research aims to optimize a more scalable, cost-effective, robust, and safer production process for a vaccine candidate that prevents a variety of sexually transmitted infections. We investigated the parameters for transgene bank establishment, efficient biomass production, protein extraction, and product purification. We also studied the stability of the vaccine candidate under various conditions and established a set of analytical assays for characterizing in-process samples as well as the final purified product. The challenges in eliminating endotoxin and addressing compliance with FDA's current Good Manufacturing Practice (cGMP) regulations will also be discussed.