Viruses and Viral Vaccines: Characterization by Nanoparticle Tracking Analysis

NTA utilizes the properties of both light scattering and Brownian motion in order to obtain the particle size distribution of samples in liquid suspension. A laser beam is passed through the sample chamber, and the particles in suspension in the path of this beam scatter light in such a manner that they can easily be visualized via a 20x magnification microscope onto which is mounted a camera. The camera, which operates at approximately 30 frames per second (fps), captures a video file of the particles moving under Brownian motion within the field of view of approximately 100 μm x 80 μm x 10 μm.

As NTA allows suspensions of nanoparticles to be visualized, sized and enumerated based on a particle-by-particle basis, its ability to determine the concentration and direct number frequency based particle size distribution profile means that virus preparations in particular can be studied in higher detail. 

It is frequently the case in vaccine production and manufacture that the size of any particular virus or phage particle is known and of secondary importance to the estimation of virus particle concentration measurement and degree of aggregation. In this regard, the ability of NTA to determine virus concentration measurement through direct visualization, irrespective of virus infectivity, is of significant value. 

Similarly, NTA’s ability to detect, size and, most importantly, measure concentration of all but the smallest viruses has led to numerous studies and assessment in this area, where it is considered to compare favorably with existing techniques.