Development of a stable mRNA prophylactic vaccine against SARS-CoV-2 omicron variant

ABSTRACT Infectious disease remains one of the leading causes of illness and mortality worldwide. The recent coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV- 2) led to widespread illness and death, disrupting public health and economy. It has been successfully mitigated thanks to the development and global application of the novel messenger RNA (mRNA) vaccine technology. While mRNA vaccines have offered significant protection, the high mutation rate of SARS-CoV-2 necessitates ongoing development of updated vaccines to combat new variants. While mRNA vaccines have shown remarkable effectiveness against COVID-19 by stimulating both humoral and cellular immune responses, the main limitation lies in the inherent instability of mRNAs at normal conditions without protection. Therefore, current mRNA and mRNA formulations require ultralow temperatures for storage and transportation. Recognizing the instability challenge, we proposed to develop a novel "RNA-plex" technology, which uses an "carrier-base" polymer to bind to mRNA molecules, preventing them from degradation in fridge or room temperature during storage. It significantly reduces the transportation and distribution costs, and makes mRNA vaccines more accessible globally, especially in areas with limited cold chain facilities. Notably, this mRNA protection technology can universally shield various mRNAs, is compatible with multiple delivery systems, and significantly enhances mRNA translation in cells, suggesting its promising potential for diverse therapeutic and research applications. In this proposal, we will apply this mRNA stabilization technology named "RNA-plex" in the development of stable and efficient vaccines for SARS-CoV-2 prevention. Specifically, we will optimize the composition and formulation of RNA-plex to maximize its protective efficacy for SARS-CoV-2 omicron variant spike protein mRNA. Next, we will apply it in preparing prophylactic lipid nanoparticle (LNP) mRNA vaccines with high stability, enhanced antigen translation efficiency, and superior vaccination effectiveness compared to conventional approaches against emerging viral threats, using the recent SARS-CoV-2 omicron variant XBB.1.5 as a proof-of-principle model. Specific Aims: Aim 1. Stabilization of SARS-CoV-2 omicron variant mRNA using RNA-plex technology and develop an LNP mRNA vaccine. Aim 2. Evaluate the efficacy of LNP-RNA-plex vaccine in eliciting immune responses and protection against SARS-CoV-2 Omicron variant.