Using quantitative proteomics to optimize Euglena gracilis as a sole-source COVID-19 vaccine delivery platform

SARS-CoV-2是2019年底出现的一种新型冠状病毒，自那以后迅速蔓延到世界各地，引发了前所未有的全球危机。SARS-CoV-2引起的COVID-19对全球卫生和经济的影响越来越大，这突出表明，除了可获得的疫苗外，还需要敏感和特定的工具来监测传播中的病毒，以保护人群免受该病毒的侵害。独特的是，绿枝草（Euglena gracilis）代表了一种多功能生物，具有成为开发单一来源COVID-19疫苗的改变游戏规则的生物技术平台的潜力。绿藻在不同的生理条件下具有多种生长策略，提供了卓越的生物适应性和培养条件范围。此外，它产生的天然佐剂paramylon正在探索作为疫苗的非化学佐剂。利用定量蛋白质组学方法，我们建议分析真核真核细胞外和分泌蛋白质组中的蛋白质组和糖蛋白质组变化，以确定关键的蛋白质网络和蛋白质特征（例如转运/靶向肽），这些蛋白质网络和蛋白质特征可以用于最大化疫苗生产的抗原提呈或可持续血清学测试开发的分泌。此外，利用缺乏paramylon的Euglena，我们还旨在鉴定有助于优化paramylon生产的蛋白质。最后，我们将定量评估表达COVID-19刺突蛋白的Euglena系蛋白质组的变化。这将有助于完善Euglena作为COVID-19疫苗唯一来源生产平台的开发。传染病专家一再强调，预计2019冠状病毒病等人畜共患病毒性疾病的爆发频率和数量将在下个世纪增加。因此，我们提出的将细叶菊开发为一种能够在新疫苗生产中快速部署的单一生物平台，也代表了为未来疫情和大流行做准备的新需要。

SARS-CoV-2 is a novel coronavirus that emerged in late 2019 and has since rapidly spread across the world causing an unprecedented global crisis. The growing impact of SARS-CoV-2 caused COVID-19 on global health and the economy has highlighted the need for sensitive and specific tools to surveil the circulating virus in addition to accessible vaccines to protect human populations against the virus. Uniquely, Euglena gracilis (Euglena) represents a versatile organism that holds the potential of being a game-changing biotechnology platform for the development of a sole-source COVID-19 vaccine. Euglena is capable of multiple growth strategies under diverse physiological conditions, providing exceptional biological adaptiveness and range of culturable conditions. Moreover, it produces the natural adjuvant paramylon that is being explored as a non-chemical adjuvant agent for vaccines. Using quantitative proteomic approaches, we propose to analyze proteome and glycoproteome changes in the Euglena extracellular and secreted proteome in order to identify key protein networks and protein features (e.g. transit / targeting peptides) that can be exploited in maximizing either antigen presentation for vaccine production or secretion for sustainable serological test development. Furthermore, using paramylon deficient Euglena we also aim to identify proteins that will contribute to the optimization of paramylon production. Lastly, we will quantitatively assess changes in the proteome of Euglena lines expressing COVID-19 spike proteins. This will contribute to refining the development of Euglena as a sole-source production platform for a COVID-19 vaccine. Infectious disease experts have repeatedly stressed that outbreaks of zoonotic viral diseases such as COVID-19 are expected to increase in frequency and number over the next century. Our proposed development of Euglena gracilis as a single organism platform capable of rapid deployment in the production of new vaccines therefore also represents an emerging necessity in preparing for future outbreaks and pandemics.