Journal of Vaccine Research 2024, Vol.14, No.3, 95-106 http://medscipublisher.com/index.php/jvr 99 its entry into cells. LNPs are typically composed of ionizable lipids, cholesterol, phospholipids, and polyethylene glycol (PEG)-lipid conjugates. These components work together to form stable particles that can encapsulate the mRNA, protect it from degradation, and promote cellular uptake (Hassett et al., 2019). Recent advancements in LNP technology have focused on improving the efficiency and safety of these delivery systems. For example, the development of biodegradable ionizable lipids has reduced the potential toxicity associated with LNPs while maintaining high levels of protein expression and immunogenicity (Jackson et al., 2020). Additionally, targeted delivery systems are being explored to direct the LNPs to specific cell types or tissues, thereby enhancing the vaccine's effectiveness and minimizing off-target effects (Buschmann et al., 2021). Beyond LNPs, other delivery technologies are also being investigated. These include polymer-based nanoparticles, peptides, and other nanomaterial-based carriers. Each of these delivery systems has unique properties that can potentially enhance the delivery and efficacy of mRNA vaccines. For instance, polymer-based nanoparticles can provide sustained release of mRNA, while peptide-based systems can facilitate targeted delivery to specific cell types (Liang et al., 2021). 4.3 Scalability and manufacturing The scalability and manufacturing of mRNA vaccines have been major considerations, especially in the context of responding to global health emergencies such as the COVID-19 pandemic. One of the significant advantages of mRNA vaccine technology is its potential for rapid and scalable production. Unlike traditional vaccines, which often require the cultivation of live viruses or bacteria, mRNA vaccines can be produced using cell-free systems. This simplifies the production process and allows for rapid scaling (Rosa et al., 2021). The manufacturing process typically involves the in vitro transcription of mRNA from a DNA template, followed by purification and encapsulation in LNPs. Advances in purification techniques, such as chromatography and tangential flow filtration, have improved the efficiency and yield of mRNA production. Furthermore, the modular nature of mRNA vaccine production allows for the rapid adaptation of the manufacturing process to produce vaccines against new or emerging pathogens (Jackson et al., 2020). To meet the global demand for mRNA vaccines, companies have invested in expanding their production capacities and optimizing manufacturing workflows. Innovations in automation and process optimization have also contributed to the ability to produce large quantities of mRNA vaccines efficiently. These advancements have positioned mRNA vaccines as a promising platform for addressing not only current but also future public health challenges (Gote et al., 2023). 5 mRNA Vaccines in Infectious Diseases 5.1 Influenza and other viral infections Before the advent of COVID-19, significant efforts were made to develop mRNA vaccines for a variety of viral infections, including influenza. Traditional influenza vaccines, which rely on inactivated or attenuated viruses, face challenges such as the need for annual reformulation and varying effectiveness. mRNA vaccines offer a promising alternative due to their rapid development cycle and the ability to encode multiple antigens, potentially enhancing their effectiveness (Pardi et al., 2018). Studies on mRNA vaccines for influenza have demonstrated their ability to induce strong immune responses and provide protection in preclinical models. For instance, mRNA vaccines encoding hemagglutinin, a key influenza virus surface protein, have shown to be effective in eliciting neutralizing antibodies and T-cell responses, offering protection against influenza challenge in animal models (Jackson et al., 2020). Moreover, the flexibility of mRNA technology allows for the rapid adaptation of vaccines to match circulating strains, addressing the antigenic drift and shift that characterize influenza viruses. Beyond influenza, mRNA vaccine platforms have also been explored for other viral infections such as rabies, Zika, and cytomegalovirus. These studies have consistently shown that mRNA vaccines can induce potent immune
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