H1N1 influenza virus-like particles: physical degradation pathways and identification of stabilizers.

A simple and rapid approach to vaccine stabilization has been applied to a novel virus-like particle (VLP) that contains the primary influenza antigens (hemagglutinin and neuraminidase surface proteins). A complement of spectroscopic and light scattering techniques was used to characterize the physical stability of influenza VLPs as a function of temperature and pH, two pharmaceutically relevant stress factors. The resulting data set was mathematically converted into a three-color empirical phase diagram (EPD) that illustrates changes in physical state as a function of these stress factors. Conditions of temperature and pH corresponding to apparent phase boundaries in the EPD were then used to screen for inhibitors of VLP aggregation from a library of generally recognized as safe compounds. Several potent inhibitors of VLP aggregation were identified; of these, trehalose, sorbitol, and glycine were all found to exert significant stabilizing effects on viral protein tertiary structure and/or membrane integrity.