Size distribution analysis of influenza virus particles using size exclusion chromatography.

•SEC of 100nm virus particles allows for separation of aggregates, monomers and fragments.•Separation is based on inter- and intra-particle volume.•Retention of the whole virus particle peak correlates with DNA purity.•Conventional activity based assays can lead to overestimation of influenza virus titers.•HA activity is not directly linked to virus particle integrity.