Vaccine protein stabilization in silica

Conference Dates

June 17-22, 2018


Successful eradication or control of prevailing infectious diseases is linked to vaccine efficacy, stability and distribution. The majority of protein based vaccines are transported at fridge temperatures (‘cold-chain’) to maintain their potency. However, this has been shown to be problematic. Proteins are inherently susceptible to thermal fluctuations, occurring during transportation, causing them to denature. This leads to ineffective vaccines and an increase in vaccine preventable diseases, especially in low-income countries. Our research utilizes silica to preserve and eventually distribute vaccines at room temperature, thereby decreasing the load on ‘cold-chain’ logistics. The methodology is based upon sol-gel chemistry where soluble silica is employed to encapsulate, ensilicate, vaccine proteins1. This yields protein-loaded silica nanoparticles in the form of a dry powder (figure 1). The material is stored at room temperature and stress tested (heating, 80°C, 2 hours). Subsequently, ensilicated protein is released using a fast chemical process. Silica, silicon dioxide, is an inert biocompatible material with certain ceramic properties that is beneficial in this scenario. The proof-of-concept work was done with a common vaccine antigen: tetanus toxin C fragment2. This protein is the immunogenic part of the full tetanus neurotoxin. Analysis of TTCF protein before and after stabilization in silica revealed full retention of protein structure at various levels. Additionally, specific antibody binding indicated retention of immunogenic epitopes (figure 2). These finding suggest that this methodology could reduce or perhaps eliminate vaccine waste. More work will be undertaken to verify protein stabilization and functional retention in vivo.

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