Biophysical characterisation of the structure of a SARS-CoV-2 self-amplifying - RNA (saRNA) vaccine

Abstract

The current SARS-Covid-2 pandemic has led to an acceleration of messenger - ribonucleic acid (mRNA) vaccine technology. The development of production processes for these large mRNA molecules, especially self-amplifying mRNA (saRNA) has required concomitant development of analytical characterisation techniques. Characterising the purity, shape and structure of these biomolecules is key to their successful performance as drug products. This paper describes the biophysical characterisation of the Imperial College London Self-amplifying viral RNA vaccine (IMP-1) developed for SARS-CoV-2. A variety of analytical techniques have been used to characterise the IMP-1 RNA molecule. In this paper we use UV spectroscopy, dynamic light scattering (DLS), size-exclusion chromatography small angle scattering (SEC-SAXS) and circular dichroism (CD) to determine key biophysical attributes of IMP-1. Each technique provides important information about the concentration, size, shape, structure and purity of the molecule. Statement of significanceThis paper is highly significant as it provides a prescient biophysical characterisation of an efficacious Sars-Cov-2 vaccine self-amplifying (sa)RNA molecule. RNA vaccines have been a major scientific breakthrough of the Covid-19 pandemic. saRNA is a further development of conventional mRNA vaccines, amplifying the RNA of interest in the cell, allowing the vaccine to be administered at lower dosages. These new biologics are distinct from previous biologics and have required distinct analytical characterisation. The analytics described herein provide detailed information on the size, shape, and structure of the RNA molecule. This paper is therefore an important step in characterising large saRNA biological relevant molecules.