Doing Our Best: Quality Control Antiviral Vaccines with Litesizer

Abstract

The particle size of vaccines has a considerable influence on their half-life in vivo, as well as on their uptake by antigen-presenting cells. The surface charge of particles is also suspected of influencing the same parameters. Here we use DLS and ELS to characterize respectively the particle size and zeta potential of two inactivated antiviral vaccines. A tick-borne encephalitis (TBE) vaccine displays a monomodal particle size distribution in the lower micrometer range, corresponding to the expected size of the aluminum salt adjuvant. A cell-based influenza vaccine, in contrast, is shown to contain both split viruses (ca. 30 nm) and larger aggregates (ca. 250 nm). Zeta potential measurements indicate that both vaccines consist of weakly anionic particles. Interestingly, we demonstrate that simulated cold chain disruptions (heat treatment, freeze-thawing) induce significant changes in the particle size distribution of both vaccines.