Highly proliferative silkworm cell line: Development of a new line for recombinant protein production

Recombinant proteins such as vaccines, antibodies, and enzymes play essential roles in research, veterinary, and medical applications. The insect cell-baculovirus expression system is widely used for recombinant protein production, and silkworm (Bombyx mori) cells can also be used because they are susceptible to baculovirus. However, many silkworm-derived cell lines suffer from limitations such as slow proliferation and the persistent presence of B. mori latent virus (BmLV). To overcome these issues, we established a new cultured cell line, BmMAX7050np, from B. mori embryos and evaluated its growth characteristics and protein productivity. BmMAX7050np exhibited approximately twice the proliferation rate compared to the commonly used BmN strain and maintained a growth rate comparable to that of Sf9 cells. No detectable BmLV was observed. The cell line supported both adherent and suspension cultures, making it suitable for scalable protein production. Several intracellular and secreted proteins were used as target proteins to evaluate their production capacities under the control of the baculovirus polyhedrin promoter. BmMAX7050np and Sf9 cells showed comparable protein yields. Collectively, these findings indicate that BmMAX7050np is a promising cell line for laboratory and industrial-scale protein production.