Physical Characterization of Icosahedral Virus Ultra Structure, Stability, and Integrity Using Electrospray Differential Mobility Analysis

Abstract

We present a rapid and quantitative method to physically characterize the structure and stability of viruses. Electrospray differential mobility analysis (ES-DMA) is used to determine the size of capsomers (i.e., hexons) and complete capsids. We demonstrate how to convert the measured mobility size into the icosahedral dimensions of a virus, which for PR772 become 68.4 nm for vertex-to-vertex, 54.4 nm for facet-to-facet, and 58.2 nm for edge-to-edge lengths, in reasonable agreement with dimensions from transmission electron microscopy for other members of the family Tectiviridae (e.g., PRD1). These results indicate ES-DMA's mobility diameter most closely approximates the edge-to-edge length. Using PR772's edge length (36.0 nm) and the size of the major capsid hexon (≈8.4 nm) from ES-DMA with icosahedral geometry, PR772's T = 25 symmetry is confirmed and the number of proteins in the capsid shell is determined. We also demonstrate the use of ES-DMA to monitor the temporal disintegration of PR772, the thermal degradation of PP7, and the appearance of degradation products, essential to viral stability assays. These results lay groundwork essential for the use of ES-DMA for a variety of applications including monitoring of vaccine and gene therapy vector products, confirmation of viral inactivation, and theoretical studies of self-assembling macromolecular structures.

Electrospray–differential mobility analysis of bionanoparticles

“…This size dependence is usually accounted for by calibrating CPCs against electrometers and is called the CPC collection efficiency (η CPC ) [30]. It should be pointed out that modifications, including use of different working fluids and operating temperatures can lower the size limit to ~ 1 nm [31]. Further discussion about the operating principle of the CPC can be found elsewhere [29].…”

Evaluation of electrospray differential mobility analysis for virus particle analysis: Potential applications for biomanufacturing

“…For example, a number of studies measured the size of both large and small viruses (Bacher et al, 2001;Bothner and Siuzdak, 2004;Wick et al, 2005;Hogan et al, 2006;Thomas et al, 2004;Cole et al, 2009;Kaddis et al, 2007;Laschober et al, 2008;Pease et al, 2009;Wick et al, 2007). Using ES-DMA size distributions Pease et al (2011) determined the symmetry and number of proteins per capsid for PR772 (Family Tectiviridae, Genus Tectivirus), a biosafety level 1 (BSL1) simulant of adenovirus. Lute et al (2008) and Wick et al (2007) extended ES-DMA analyses to viruses of particular interest to biomanufacturers and filter firms by characterizing the size distributions of murine minute virus (Family Parvoviridae, parvovirus) and the BSL1 models, PP7 (Family Leviviridae, Genus Levivirus) and X174 (Family Microvaridae, Genus Microvirus) (Wick et al, 2007) used in virus filtration studies (Lute et al, 2008) and in the Parenteral Drug Association's (PDA) new nomenclature standards for small and large virus retentive filters.…”

Mass Spectrometry in Virological Sciences

“…MS-based analysis of viral capsid assembly and stability is a good example of another interesting application. Pease et al, using ESI-DMA technique, have shown, in addition to previously described experiments (Bacher et al, 2001;Hogan et al, 2006), that it is possible to measure the geometry of the viral particles, their structure and integrity (Pease et al, 2011). As a model object, phage PR772 was used, which belongs to the Tectiviridae family.…”