Low-concentration sucrose improves respiratory syncytial virus viability under thermal and Freeze-Thaw stress: An...

Respiratory Syncytial Virus (RSV) is a major concern in infants, the elderly, and immunocompromised individuals. RSV is a thermolabile virus posing challenges for vaccine development and laboratory handling. We evaluated whether low concentrations of sucrose could enhance RSV stability under standard and stress-inducing conditions. Using plaque assays on HeLa cells, we tested sucrose at concentrations from 0.1 % to 7 %. A statistically significant increase in RSV titer (∼40 %) was observed only with 0.3 % sucrose (p = 0.0009). Follow-up experiments demonstrated that 0.3 % sucrose significantly protected RSV from thermal degradation at 25°C and 37°C and from viability loss over three freeze-thaw cycles. Compared to previously reported stabilizers such as high-concentration sucrose, trehalose, or gelatin, our low-dose sucrose formulation avoids viscosity and processing issues while still offering practical enhancement. This is particularly relevant to live-attenuated vaccine platforms, which require stable formulations to maintain potency during storage and transport. These findings suggest 0.3 % sucrose provides a cost-effective, scalable strategy for improving RSV viability during handling and formulation.