For instance, it is an excipient in some vaccines approved by the FDA, including live attenuated influenza, measles mumps rubella, shingles zoster, varicella, and yellow fever vaccines under the brand names Flumist®, MMR II®, Zostavax®, Varivax®, and YF-Vax®, respectively. Many investigators have used gelatin for decades as a stabilizer in vaccine development. Gelatin is preferably used as a stabilizer due to its high biocompatibility, biodegradability, low immunogenicity, and low material cost. Gelatin is a bulking agent and acceptable material for medical use and can enhance virus stability at ambient temperatures. However, to improve these strategies, many excipients are used in the formulation to increase the thermal stability of viral particles, including sucrose, dextran, albumin, and gelatin. The cost and potential loss of virus potency in the freeze-drying process or during reconstitution are due to protein destabilization, alteration of lipid layers (enveloped viruses), or occurrence of stress related to changes in the internal and external virus environment. However, these strategies create some issues, including the challenges of cost and extensive infrastructure and maintenance for cold chain transport, especially for deep freezing. There are two main strategies currently used to improve virus stability: cold chain storage and freeze-drying. Nevertheless, the stability of these enveloped and nonenveloped model viruses in storage formulations is poorly understood, and virus research and human infectious disease research often employ animal-derived virus models in the virus families. The lipid envelope plays a crucial role in virus lability and typically requires a temperature lower than 4 ☌ for short- or long-term storage. The latter is more thermostable than the former group. Viruses can be placed in two main categories based on the presence or absence of a lipid envelope around their capsid, which classifies them as an enveloped or nonenveloped virus, respectively. Many viruses used for medical research or therapeutic purposes exhibit a lack of thermostability in ambient environments. The results demonstrated that 5% of 4000 MW hydrolyzed gelatin formulation can act as a relevant stabilizer for the thermal stability of viruses in medical research and application. All four viruses exhibited stability at 4 ☌ for at least 8 weeks, BHV or AdV remained stable for over 30 weeks of storage, and at 25 ☌, AdV and RV remained stable for 8 weeks. Based on the gelatin type, BHV in alkaline-treated hydrolyzed gelatin samples were unexpectantly more stable than in acid-treated hydrolyzed gelatin sample. The BHV model virus was considered stable after 3 weeks in hydrolyzed gelatin (MW: 4000) with a 0.8 LRV (log10 reduction value) at 25 ☌ or a 0.2 LRV at 4 ☌, compared to the stabilities observed in higher MW gelatin (60,000 and 160,000) with an LRV above 1. Using the model virus liquid formulation, the stability of multiple enveloped and nonenveloped RNA and DNA viruses, including parainfluenza virus, reovirus (RV), BHV, and adenovirus (AdV), was monitored over up to a 30-week storage period. Methodsīovine herpesvirus (BHV) was used as a model virus to examine the molecular weight (MW), concentration and gelatin type and to optimize virus stability in liquid formulations at 25 ☌ and 4 ☌. The thermal stability of viruses in gelatin liquid formulations for medical research and application is poorly understood and this study aimed to examine the thermal stability of 4 enveloped and nonenveloped DNA and RNA viruses in hydrolyzed gelatin liquid formulations.
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