Thermolabile nature of commercially available vaccines necessitates their storage, transportation and dissemination under refrigerated condition. Maintenance of continuous cold chain at every step increases the final cost of vaccines. Any breach in the cold chain, even for a short duration results in the need to discard the vaccine. As a result, there is a pressing need for the development of thermostable vaccines. In this proof of concept study, we showed that E. coli curli-GFP fusion protein remains stable in freeze-dried yeast powder for more than a 13 and 6 months when stored at 30 °C and 37 °C respectively. Stability of the heterologous protein remains unaffected during the process of heat-inactivation and lyophilization. The mass of lyophilized yeast powder remains almost unchanged during the entire period of storage. Expressed protein remains intact even after two cycles of freeze and thaws. The protease deficient strain appears ideal for the development of whole recombinant yeast-based vaccines. The cellular abundance of expressed antigen in dry powder after a year was comparable to freshly lyophilized cells. SEM microscopy showed the intact nature of cells in powdered form even after a year of storage at 30 °C. Observation made in this study showed that freeze-dry yeast powder can play a vital role in the development of thermostable vaccines.

中文翻译：

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冻干酵母粉用于无佐剂的热稳定疫苗递送

市售疫苗的不耐热性质使其需要在冷藏条件下进行存储，运输和传播。在每个步骤中维持连续的冷链会增加疫苗的最终成本。冷链中的任何断裂，即使持续很短的时间，也都需要丢弃疫苗。结果，迫切需要开发热稳定疫苗。在此概念验证研究中，我们显示了大肠杆菌curli-GFP融合蛋白在冷冻干燥的酵母粉中分别在30°C和37°C的温度下保持稳定超过13个月和6个月。在热灭活和冻干过程中，异源蛋白质的稳定性保持不变。在整个存储过程中，冻干酵母粉的质量几乎保持不变。即使经过两次冷冻和融化，表达的蛋白质仍保持完整。蛋白酶缺陷菌株似乎是开发完整的基于重组酵母的疫苗的理想选择。一年后，干粉中表达的抗原的细胞丰度与新鲜冻干的细胞相当。SEM显微镜显示，即使在30°C储存一年后，粉末形式的细胞仍保持完整。这项研究的观察结果表明，冻干酵母粉可以在热稳定疫苗的开发中发挥至关重要的作用。SEM显微镜显示，即使在30°C储存一年后，粉末形式的细胞仍保持完整。这项研究的观察结果表明，冻干酵母粉可以在热稳定疫苗的开发中发挥至关重要的作用。SEM显微镜显示，即使在30°C储存一年后，粉末形式的细胞仍保持完整。这项研究的观察结果表明，冻干酵母粉可以在热稳定疫苗的开发中发挥至关重要的作用。