Detection of hemagglutinin spikes on influenza VLPs using automated MiniTEM analysis

During the downstream development of a viral-based vaccine or gene therapy product, information is needed on the type of structures present in the sample, their relative amount and correlation of their presence to biological effects. A robust method is needed that allows reliable classification of the structures.

Influenza VLP samples, produced using the BEVS/IC system, and taken at any point during or after the downstream processing, typically comprise a mix of particles with various morphological characteristics. The primary influenza VLP particle can vary in both shape and size and additionally show differences in the distribution of surface hemagglutinin (HA) structures.

In this case study, we show how MiniTEM can be used to automatically generate a relative quantitative analysis of different particle classes.

A structural footprint of the entire sample is thus obtained with quantitative data on number, size and portion of each particle category in different samples. The data obtained with MiniTEM may not exactly correspond to the absolute number of each particle in solution but can be used to compare samples and evaluate the behaviour of viral particles under different process conditions.