Non-destructive Remote Determination of Total Native Protein Concentration in Virus-Like Particle Vaccine Preparations

Introduction. Virus-Like Particles (VLPs) are nanoscale entities characterized by surface shape heterogeneity and enhanced emission activity in the millimeter wavelength range (30-300 GHz), which is influenced by external physical factors such as heating or electromagnetic radiation. This phenomenon presents opportunities for the noninvasive determination of accurate concentrations of the protein component in commercially prepared VLP vaccines. Objective. To propose a modern and rapid approach for the quantitative determination of native proteins in VLP-containing vaccines, which enables research to be conducted without opening the primary packaging. Materials and methods. Vaccines imitating rotavirus (Gam-VLP-Rota) and SARS-CoV2 virus (Gam-VLP-multivac) were studied. The density of the radiothermal emission flux at extremely high frequency (EHF) wavelengths was measured using a TES-92 device. The reference values for protein concentration in vaccines, prior to the addition of the adjuvant, were measured using the commercial "Micro BCA™ Protein Assay Kit". The dimensional characteristics of the VLP vaccine were analyzed using dynamic laser light scattering (Zetasizer Nano ZSP). Results. A strong linear correlation (r = 0.99) was established between the flux density of radiothermal emission and the protein content in vaccines, allowing for analysis without opening the packaging. The validation procedure for this technique assessed linearity, accuracy, and intra-laboratory precision for Gam-VLP-multivac. Conclusion. The values of the intrinsic radiothermal emission flux density enabled the determination of the native concentration of complex-shaped virus-like nanoparticles in vaccines without the need to open the primary packaging, irrespective of the presence of an adjuvant. Keywords: VLP, Virus-Like Particles, quality control, protein concentration determination, radiothermal emission.