A yeast surface display method tailored for nanobody display

家禽业是加拿大经济的主要参与者，2011年对加拿大GDP的贡献超过65亿美元，出口额约为3.5亿美元。人畜共患病细菌感染的家禽对人类消费构成了严重挑战，特别是现在人畜共患病病原体对传统抗生素的耐药性越来越强。AbCelex是一家加拿大公司，开发针对人畜共患病细菌的单域抗体，也称为纳米抗体。AbCelex纳米抗体可防止家禽肠道的病原体定植，从而使动物更健康，同时减少人类食用禽肉的细菌污染。纳米抗体商业化的主要障碍是与生产和纯化过程相关的高成本。AbCelex目前正在使用一种在酵母表面表达纳米抗体的策略，该策略消除了关键的纯化步骤，有可能克服市场的主要障碍。然而，现有的用于纳米抗体酵母表面展示的方法远不理想，因为它们仅在~20%的细胞中产生表面表达，降低了效率并因此增加了成本。AbCelex和多伦多大学Sergio Peisajovich教授实验室之间的合作旨在设计一种针对纳米抗体的新型酵母表面展示方法，以将表面展示水平提高到至少80%的细胞，从而消除商业化的主要障碍。为了实现这一目标，我们将系统地筛选所有合适的酵母GPI锚定细胞壁蛋白，以确定最佳的融合伴侣，以在细胞表面展示纳米抗体。用于预防家禽细菌污染的AbCelex纳米抗体饲料添加剂可以为家禽业的主要问题之一提供急需的补救措施。该提案将大大有助于消除AbCelex纳米抗体商业化的主要障碍，从而使加拿大经济的重要参与者受益，同时有助于减少加拿大和世界各地的食源性疾病。

The poultry industry is a major player in Canada's economy, contributing more than ~$6.5B to Canada's GDP in 2011, with ~$350M in exports. Zoonotic bacteria infected poultry poses a serious challenge to human consumption, particularly now that zoonotic pathogens are becoming increasingly resistant to traditional antibiotics. AbCelex is a Canadian company developing single-domain antibodies, also known as nanobodies, against zoonotic bacteria. AbCelex nanobodies prevent pathogen colonization of poultry gut, resulting in healthier animals while reducing bacterial contamination of poultry meat for human consumption. A major barrier to nanobodies commercialization is the high cost associated with the production and purification processes. AbCelex is currently using a strategy for expression of nanobodies on the yeast surface that eliminates key purification steps, potentially overcoming a major barrier to market. However, existing methods for nanobody yeast surface display are far from ideal, as they result on surface expression only in ~20% of the cells, reducing efficiency and thus increasing cost. The collaboration between AbCelex and the laboratory of Prof. Sergio Peisajovich, at the University of Toronto, is aimed at engineering a novel yeast surface display method tailored for nanobodies to increase surface display levels to at least 80% of the cells, thus eliminating a major barrier to commercialization. Towards this goal, we will systematically screen all suitable yeast GPI-anchored cell wall proteins to identify optimal fusion partners to display nanobodies on the cell surface. AbCelex nanobody-based feed additive for prevention of bacterial contamination in poultry could provide a much-needed remedy to one of the poultry industry major problems. This proposal will substantially contribute to eliminate a major barrier to AbCelex nanobody commercialization, thus benefiting an important player in Canada's economy, while contributing to reduce foodborne diseases in Canada and around the world.