Comparative Evaluation of Carbohydrate, Amino Acid, and Ionic Liquid Excipients for Flavivirus Vaccine Stabilization.

Live-attenuated flavivirus vaccines (yellow fever, dengue, and Japanese encephalitis) exhibit poor thermal stability in liquid formulations, requiring lyophilization and storage between 2 and 8 °C to maintain potency. We evaluated carbohydrates, amino acids, and choline-based ionic liquids as preservatives for vaccine-like flavivirus. Among the carbohydrates tested, trehalose and sucrose provided greatest stabilization, while histidine demonstrated the strongest stabilizing effect among amino acids. Trehalose-histidine and sucrose-histidine combinations produced synergistic effects, preserving viral infectivity more effectively than individual components. Choline chloride and choline acetate formulations, despite their established efficacy in protein stabilization, demonstrated limited enhancement of flavivirus thermal stability compared to carbohydrate-amino acid formulations. Trehalose-histidine combinations provided up to 19.4-fold improved titer retention compared to buffer controls, with consistent superiority across all three flavivirus species tested, while choline-based ionic liquid formulations showed moderate stabilizing effects but were consistently outperformed by carbohydrate-amino acid approaches.