STUDY OF WUPyV VIRUS-LIKE PARTICLES IMMUNE COMPLEX FORMATION WITH MONOCLONAL ANTIBODIES BY SPECTROSCOPIC ELLIPSOMETRY AND QUARTZ CRYSTAL MICROBALANCE WITH DISSIPATION

Viral infections can cause severe inflammations. Antibodies, produced during these infections or after vaccination, form immune complex with antigens as a response of immune system. Formed immune complex can also participate in inflammation processes. Overactivation and induced inflammation during viral infections or vaccination can cause unwelcome effects to human organism. In order to avoid overactivation, it is of great significance to understand immune cells’ response to immune complex.
In our study, we investigated differences between immune complex formations of recombinant virus-like particles (VLPs) derived from the major capsid protein VP1 of human Washington University (WU) human polyomavirus (PyV), self-assembling to spherical nanoparticles, and a set of VLP-specific monoclonal antibodies (mAbs). We used a collection of mAbs IgG1, IgG2a and IgG2b subclass [1].
For this investigation we utilized two surface-sensitive methods: spectroscopic ellipsometry (SE) and quartz crystal microbalance with dissipation (QCM-D). SE is an optical technique, which can provide valuable information about sensing surfaces’ dielectric properties, such as refractive index or thickness. QCM-D is an acoustic method, based on sound waves, and it gives knowledge about mechanical and viscoelastic characteristics of the layer. SE and QCM-D combination is highly suitable for the real-time detection of protein-protein interactions, as it does not require labelling of proteins and it is non-invasive and non-destructive to analytes.
From data, obtained during SE measurements, the equilibrium dissociation and association constants, dissociation and association rate constants were calculated by applied mathematical model based on encounter theory. All tested mAbs were determined to be from medium to very high affinity to VLPs. Simultaneously, data from QCM-D measurements revealed different viscoelastic properties of mAbs and immune complexes layers and possible mechanisms for mAbs binding to VLPs.