Productivity Improvement of Human Papillomavirus-like Particles in Insect Cells Using Hyper-Expression Baculovirus Vector.

Background/Objectives: Virus-like particle (VLP) vaccines based on human papillomavirus (HPV) L1 proteins have high efficacy for preventing cervical cancer and other HPV-associated diseases. The production yields of commercial HPV VLPs remain suboptimal. We aimed to improve HPV VLP production efficiency using a hyper-expression vector system for the expression of L1 proteins of four major HPV serotypes-HPV 6, 11, 16, and 18. Methods: HPV L1 proteins were expressed in Trichoplusia ni (Hi5) insect cells via a hyper-expression baculovirus vector system. Following cell lysis using a microfluidizer, VLPs were purified through a two-step chromatographic process. Particle morphology was characterized using transmission electron microscopy and dynamic light scattering. Immunogenicity was evaluated using a murine model; mice received three intramuscular injections of the purified quadrivalent VLPs. The resulting IgG and neutralizing antibody responses were compared with those elicited by the commercial quadrivalent vaccine, Gardasil. Results: The L1 proteins from HPV 6, 11, 16, and 18 were successfully expressed at high levels in Hi5 cells, forming uniformly sized VLPs with hydrodynamic diameters of 50-60 nm. The average production yield of the quadrivalent VLPs exceeded 40 mg/L, an improvement over conventional yields. The candidate VLPs elicited strong HPV-specific IgG and neutralizing antibody responses in mice, comparable to those induced by Gardasil. Conclusions: The hyper-expression baculovirus vector system enables high-yield production of HPV L1 VLPs with desirable structural and immunogenic properties. This approach holds promise for the cost-effective and scalable manufacturing of next-generation HPV VLP vaccines, facilitating broader global access to HPV immunization.