Abstract
The devastating global toll precipitated by the SARS CoV-2 outbreak and
the profound impact of vaccines in stemming that outbreak has
established the need for molecular platforms capable of rapidly
delivering effective, safe and accessible medical interventions in
pandemic preparedness. We describe a simple, efficient and adaptable
process to purify SARS CoV-2 virus-like particles (VLPs) that can be
readily scaled for manufacturing. A rapid but gentle method of
tangential flow filtration using a 100 kDa semi-permeable membrane
concentrates and buffer exchanges 0.5 L of SARS CoV-2 VLP containing
supernatant into low salt and optimal pH for anion exchange
chromatography. VLPs are washed, eluted under high salt, dialysed into
physiological buffer, sterile filtered and aliquoted for storage at –
80 0C. Purification is completed in less than two
days. A simple quality control process includes Western blot for
coincident detection of Spike, Membrane and Envelope protein as a proxy
for intact VLP, ELISA to detect conformationally sensitive Spike using
readily available anti-Spike and/or anti-RBD antibodies, and negative
stain and immunogold electron microscopy to validate particulate, Spike
crowned VLPs. This process to purify SARS CoV-2 VLPs for preclinical
studies serves as a roadmap for preparation of more distantly related
VLPs for pandemic preparedness.