Non-Destructive Measurement of Target Protein Content in Leaves for Plant-Made Pharmaceutical Protein Production

在这项研究中，我们旨在建立一种基于病毒载体的全植物瞬时基因表达系统，利用叶绿素（Chl）荧光测定叶片中药物蛋白含量的无损测量技术。将含有血凝素（HA） cDNA（流感疫苗抗原）和烟叶病毒复制子的质粒载体，通过转化的农杆菌真空浸润，导入到本烟植物中。在基因导入后的第3 ~ 6天，叶片中HA蛋白含量显著增加。同时，叶片的光合能力明显下降。研究表明，通过测量Chl荧光参数，包括光系统II的量子效率和热耗散活性，可以检测到光合能力的下降，这表明Chl荧光测量可能是监测叶片中HA含量动态的有用技术。

In this study, we aimed at developing a non-destructive measurement technique using chlorophyll (Chl) fluorescence to quantify pharmaceutical protein content in leaves in a viral vector-based transient gene expression system using whole plants. A plasmid vector containing a cDNA of hemagglutinin (HA), an influenza vaccine antigen, as well as a tobamoviral replicon, was introduced into Nicotiana benthamiana plants via vacuum-infiltration with the transformed agrobacteria. The HA protein content in leaves increased from 3 d to 6 d after the gene introduction event. Simultaneously, the photosynthetic capacity of leaves markedly declined. It was demonstrated that this decrease in photosynthetic capacity can be detected by measuring Chl fluorescence parameters including the quantum efficiency and thermal dissipation activity of photosystem II, suggesting that the Chl fluorescence measurement can potentially be a useful technique for monitoring the dynamics of HA content in leaves.