2025

  • A bivalent COVID-19 mRNA vaccine elicited broad immune responses and protection against Omicron subvariants infection

    Abstract

    Continuously emerging SARS-CoV-2 Omicron subvariants pose a threat thwarting the effectiveness of approved COVID-19 vaccines. Especially, the protection breadth and degree of these vaccines against antigenically distant Omicron subvariants is unclear. Here, we report the immunogenicity and efficacy of a bivalent mRNA vaccine, PTX-COVID19-M1.2 (M1.2), which encodes native spike proteins from Wuhan-Hu-1 (D614G) and Omicron BA.2.12.1, in mouse and hamster models. Both primary series and booster vaccination using M1.2 elicited potent and broad nAbs against Wuhan-Hu-1 (D614G) and some Omicron subvariants. Strong spike-specific T cell responses against Wuhan-Hu-1 and Omicron subvariants, including JN.1, were also induced. Vaccination with M1.2 protected animals from Wuhan-Hu-1 and multiple Omicron subvariants challenges. Interestingly, protection against XBB.1.5 lung infection did not correlate with nAb levels. These results indicate that M1.2 generated a broadly protective immune response against antigenically distant Omicron subvariants, and spike-specific T cells probably contributed to the breadth of the protection.

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  • Process development of tangential flow filtration and sterile filtration for manufacturing of mRNA-lipid nanoparticles: A study on membrane performance and filtration modeling

     Abstract

    Lipid nanoparticles (LNPs) are the most studied delivery systems for mRNA therapeutics and have gained importance in both industry and academia following the approval of multiple mRNA-LNP-based vaccines since 2021. The COVID-19 pandemic proved the remarkable efficacy and rapid deployment of mRNA-LNP vaccines, reinforcing their potential for broader therapeutic and vaccine applications. Currently, multiple mRNA-LNPs are in various stages of preclinical and clinical development. LNPs are sensitive to the manufacturing process, and to mitigate the risks associated with bringing an mRNA-LNP from benchtop to industrial scale, it is recommended to have a systematic process development approach, including mathematical modeling and statistical analysis. Among the unit operations required for mRNA-LNP manufacturing, concentration and buffer exchange by tangential flow filtration (TFF), as well as sterile filtration, are challenging and must be optimized to guarantee process scalability and product quality, while avoiding issues such as membrane fouling and incorrect filter capacity. This study investigates the optimization of TFF and sterile filtration parameters to manufacture higher concentration mRNA-LNPs necessary for cancer vaccines, particularly personalized cancer vaccines. Various flat-sheet TFF cartridges were tested under different process parameters, including flow rate and transmembrane pressure (TMP), to identify the most effective process conditions. Furthermore, the sterile filtration of mRNA-LNPs was analyzed using the gradual plugging model, providing insights into improving filter capacity, optimizing filtration pressures, and defining the design space for large-scale manufacturing. These findings contribute to the development of a robust and scalable mRNA-LNP manufacturing process ensuring product quality.

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