Production of the SARS‐CoV‐2 receptor‐binding domain in stably transformed rice plants for developing country applications

The SARS-CoV-2 Spike Protein Receptor-Binding Domain Expressed in Rice Callus Features a Homogeneous Mix of Complex-Type Glycans

“…In one informative example, the HIV-neutralizing monoclonal antibody 2G12 was expressed in rice, and its glycan structure was compared to the same antibody produced in maize, tobacco, and Chinese hamster ovary (CHO) cells, the latter being the gold standard for antibody manufacture [16]. Whereas 10-13% of the maize 2G12 heavy chain was devoid of glycans, with the remainder mainly comprising complex-type glycans (if the product was secreted) or oligomannose glycans (if retained in the endoplasmic reticulum, ER) along with a small proportion of single GlcNAc residues [26], the proportion of aglycosylated heavy chain molecules increased to 50% in rice, along with 33% vacuolar-type complex N-glycans, 13% single GlcNAc residues, and 4% oligomannose glycans [17].…”

“…We previously evaluated the expression of RBDs in transgenic rice lines and confirmed the accumulation of a functional, correctly folded RBD protein in rice callus and seeds [16]. Recombinant proteins produced in rice often display simpler and more homogeneous glycans than the same proteins produced in animal cells, or even in other plants such as tobacco, which may reflect the adaptation of cereal post-translational modification pathways to produce homogeneous seed storage proteins [17].…”

Recent advances in expression and purification strategies for plant made vaccines

“…Production of vaccine antigen in plant cells has great potential to eliminate prohibitively costly and complex fermentation, simplify its transportation and distribution, eliminate sterile injections and improve the shelf-life for years at ambient temperature (Kurup and Thomas, 2020;Khan and Daniell, 2021). There are several plant species where recombinant vaccines have been expressed to achieve oral delivery such as potato (Mason et al, 1996;Mason et al, 1998), rice (Oszvald et al, 2007;Qian et al, 2008;Fukuda et al, 2018;Saba-Mayoral et al, 2023), banana, tomato (Lou et al, 2007;Davod et al, 2018;Hoshikawa et al, 2019), lettuce (Kim et al, 2007), tobacco (Hahn et al, 2007), alfalfa (Wigdorovitz et al, 1999), wheat (Shi et al, 2023), spinach and carrot.…”