Mamestra brassicae NIAS-Mb-32 cell strain 2g2 enables high-yield recombinant protein production in baculovirus-free and baculovirus-based insect cell expression.

The production of recombinant proteins using insect cells has been widely used for over 30 years, which contributing to life science research and biotechnology. Insect cells exhibiting enhanced N-glycosylation and recombinant protein productivity enhance the productivity of the baculovirus-insect cell system (BICS). A new highly proliferative insect cell strain, 2g2, was established from the Mamestra brassicae pupa ovary cell strain NIAS-MB-32 (RCB0413) to address the problem of Sf-rhabdovirus and to explore the newly available possibilities in BICS as well as Sf9, such as increased protein production and recombinant baculovirus amplification. The high-growth cell strain 2g2 was examined for its recombinant protein production ability and baculovirus productivity; moreover, the activity of the produced recombinant proteins was examined using Sf9 as a benchmark. Recombinant protein productivity and virus production by BICS in 2g2 was confirmed as equivalent to that of Sf9. Furthermore, we produced the severe acute respiratory syndrome coronavirus 2 spike protein in a baculovirus-free system and compared its productivity, binding activity with human angiotensin-converting enzyme 2, and N-glycosylation. The productivity and bioactivity were found to be equal to or better than that of Sf9. Moreover, N-glycosylation analysis revealed that the glycans derived from the 2g2-produced glycoproteins were mostly of the high mannose type as Sf9. Therefore, 2g2 may have the same N-glycosylation ability as Sf9. Finally, the Sf-rhabdovirus was confirmed to be negative in 2g2. Our results demonstrated that the novel insect cell strain 2g2 can serve as a protein production tool in scientific research and industrial biotechnology.