Engineered SARS-CoV-2 receptor binding domain improves manufacturability in yeast and immunogenicity in mice

Global containment of COVID-19 still requires accessible and afford-able vaccines for low-and middle-income countries (LMICs). Re-cently approved vaccines provide needed interventions, albeit at prices that may limit their global access. Subunit vaccines based on recombinant proteins are suited for large-volume microbial manufacturing to yield billions of doses annually, minimizing their manufacturing cost. These types of vaccines are well-established, proven interventions with multiple safe and efficacious commercial examples. Many vaccine candidates of this type for SARS-CoV-2 rely on sequences containing the receptor-binding domain (RBD), which mediates viral entry to cells via ACE2. Here we report an engineered sequence variant of RBD that exhibits high-yield manufacturability, high-affinity binding to ACE2, and enhanced immunogenicity after a single dose in mice compared to the Wuhan-Hu-1 variant used in current vaccines. Antibodies raised against the engineered protein exhibited heterotypic binding to the RBD from two recently reported SARS-CoV-2 variants of concern (501Y.V1/V2). Presentation of the engineered RBD on a designed virus-like particle (VLP) also reduced weight loss in hamsters upon viral challenge.

Automated summary

Subunit vaccines based on recombinant proteins are crucial tools for controlling COVID-19 due to their low manufacturing cost, scalability, and proven safety and efficacy. Engineered RBD variants exhibit high manufacturability and immunogenicity, showing enhanced immune responses after a single dose and cross-reactivity to new variants of concern.