The hydrophobicity of viruses can affect their transport, delivery, and interaction with other molecules. Virus hydrophobicity can be taken advantage of as a purification method or it can be detrimental to many pharmaceutical and environmental processes. Virus hydrophobicity can result in losses from virus adsorption to various pieces of equipment or piping in the manufacturing system. However, we can take advantage of the viral surface hydrophobicity in the downstream process of viral vectors by using hydrophobic interaction chromatography to separate viral vectors from impurities. There are currently no reliable methods to measure virus hydrophobicity as a result of changes in solution and surface conditions on a single particle scale. We have developed a method to measure how virus hydrophobicity changes, and thus how virus adsorption changes in different solution conditions using chemical force microscopy (CFM). CFM uses an atomic force microscope (AFM) with chemically modified probes to measure adhesion of different chemistries to the viral surface. CFM results have shown changes in virus hydrophobicity. With increasing ionic strength, the hydrophobicity of the model non-enveloped virus remained the same while that of the enveloped virus increased. CFM results have been compared to a conventional method of quantifying hydrophobicity in bulk by adsorption to hydrophobic butyl and phenyl chromatography beads, and the results correlate. This demonstrates that the CFM can be used to characterize virus hydrophobicity with very small amounts of viral vector, as compared to chromatography screening. It also offers an advantage of testing virus hydrophobicity in biologically relevant conditions. This technique could revolutionize the development of downstream processing by decreasing the time and cost associated with buffer selection and optimization and increase the speed of getting viral products to the market.

Characterization of virus hydrophobicity using chemical force microscopy

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.