Challenges in the Analytical Characterization of VLPs Through HPLC-Based Methods

Abstract

Characterization and quantification of virus-like particles (VLPs) through high performance liquid chromatography (HPLC)-based methods are challenging because of their large size, structural complexity, internal structural heterogeneity, and instability. Analytical techniques are essential to monitor morphology and internal structural heterogeneity at each process stage. Common analytical tools used in VLP characterization are microscopic techniques (such as transmission electron microscopy [TEM], atomic force-field microscopy [AFM], cryo-electron microscope [cryo-EM]), biochemical techniques (SDS-PAGE, western blotting), and light scattering techniques (such as dynamic light scattering [DLS], nanoparticle tracking analysis [NTA], and size-exclusion chromatography coupled with multi-angle light scattering [SEC-MALS]). However, these techniques are semi-quantitative and do not address morphology and internal heterogeneity. Therefore, HPLC-based techniques are sensitive, robust, and offer better resolution. The purity and titer of VLPs at any process stage can be monitored by reversed-phase chromatography and morphology, and stability-related issues can be monitored by the combination of HPLC and light scattering techniques like SEC-MALS. Challenges in HPLC-based methods are choosing columns with the right pore size and surface chemistry and effective sample preparations, as VLPs are very unstable and prone to fragmentation at process stages and the low titre of the VLPs. This article discusses the challenges and effective solutions for HPLC-based analytical characterization of VLPs.