Counting and Sizing of Virus and Protein Aggregates by Nanoparticle Tracking Analysis (NTA)

A new analytical system is described which provides total particle count and high-resolution size measurements for biological structures such as virus and protein aggregates. This system builds on the Nanoparticle Tracking and Analysis (NTA) technique for the simultaneous visualization and individual sizing of nanoparticles based on their Brownian motion. Virus production and purification processes rely on overall measurements of concentration such as optical density and infectivity assays which may take days to obtain results. The NTA method provides a total particle concentration result in minutes, providing a clearer picture of how the sample has been attenuated or killed by the purification process. Fluorescence measurements can be used to isolate a sub-population of interest. NTA provides the only alternative for concentration and sizing of polydisperse protein aggregates formed in the submicron range.