The vaccine preparation process is similar to that of general recombinant protein preparation. However, since the expressed proteins are antigens, they typically form virus-like particles (VLPs) (e.g., the HPV vaccine) or some type of polymer (e.g., the RSV vaccine). In the final purification stage, it is crucial to remove monomers and poorly formed VLPs. Some VLPs have larger particle sizes and can easily encapsulate impurities during formation, potentially causing side effects in the human body. Therefore, it is necessary to inhibit VLP formation in the early stages of purification and promote VLP formation by changing the liquid conditions when the purity is high, or remove VLP particles formed in the early stages. It is important to note that ion-exchange chromatography may disrupt the VLP structure during adsorption, leading to VLP disintegration. Thus, when designing antigen structures, surface charge interactions should be considered.
