SARS-CoV-2中和纳米抗体在里氏木霉中的重组表达

Expression of a SARS-CoV-2 neutralizing nanobody in Trichoderma reesei

摘要:

基于骆驼科动物单链抗体VHH结构域的纳米抗体具有分子量小、结构简单、溶解性好、稳定性强等多种优势，可通过吸入给药，在呼吸道病毒的防控中具有重要应用价值。里氏木霉是食品级的蛋白质生产宿主，其纤维素酶分泌量可达到80 g/L以上，有望用于药物蛋白的低成本生产。文中在密码子优化的基础上，使用组成型强启动子Pcdna1，实现了SARS-CoV-2中和纳米抗体Nb20在里氏木霉中的重组表达。将Nb20与里氏木霉纤维二糖水解酶CBHⅠ的N端片段融合表达，并在二者间引入胞内KEX2蛋白酶切位点，于葡萄糖培养基中摇瓶发酵48 h可生产出浓度为47.4 mg/L的Nb20蛋白。重组表达的纳米抗体能够与SARS-CoV-2刺突蛋白的受体结合区相结合，有望用于新型冠状病毒的中和。以上结果显示，里氏木霉在纳米抗体的重组表达中具有一定的应用潜力。

Abstract:

Nanobodies derived from camelid single-chain antibodies have the advantages of being small, simple, highly soluble and stable. Nanobodies can be administered by inhalation and therefore is potentially valuable for the prevention and control of respiratory viruses. Trichoderma reesei is a food-grade protein expression host with a cellulase production capacity of up to 80 g/L, which can be employed for low-cost production of therapeutic proteins. In this study, a codon-optimized SARS-CoV-2 neutralizing nanobody Nb20 was expressed in T. reesei under a strong constitutive promoter Pcdna1. Nb20 protein was fused downstream of the N-terminal fragment of cellobiohydrolase Ⅰ, and the fusion protein can be intracellularly cleaved by the KEX2 protease to release Nb20. In a shake-flask fermentation using glucose medium, 47.4 mg/L Nb20 was detected in the culture after 48 h of cultivation. The expressed Nb20 showed the ability to interact with the receptor-binding domain of SARS-CoV-2 spike protein, suggesting that it can be used for the neutralization of SARS-CoV-2. The results indicate that T. reesei has the potential for recombinant production of nanobodies.