Virus-free Tn5 insect cell lines match commercial High Five protein yields in serum-free culture
Researchers cleared two adventitious viruses from the Tn5 (High Five) insect cell line and derived clonal lines with comparable or higher protein yields, which matters for vaccine manufacturing.
A research team has found a second adventitious virus in the Trichoplusia ni cell line BTI-TN-5B1-4 (Tn5), commonly called High Five, and eliminated it together with a previously known one. The work was published in BMC Biotechnology in 2026 by Chen and colleagues biomedcentral.com
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The Tn5 line is widely used for recombinant protein production in the baculovirus-insect cell expression system because of its high productivity and strong secretion capacity. Adventitious viral contamination remains a concern, particularly in the manufacture of vaccines and therapeutic proteins, where viral safety is paramount.
Two viruses in one cell line
In 2007, a latent infection with Tn5 Cell Line Virus (TnCLV), a member of the genus Alphanodavirus, was identified in Tn5 cells. The authors now report a second virus in the same line: Bombyx mori macula-like virus (BmMLV).
To remove both, they used a co-culture protocol in which the Tn5 cells were grown with Sf9 cells across a permeable membrane. According to the authors, both viruses were successfully eliminated this way biomedcentral.com
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Clonal lines and protein yields
Clonal cell lines were established from the virus-free Tn5 cells and characterized in serum-free suspension culture. Selected lines showed growth kinetics comparable to those of commercial High Five cells and supported productive baculovirus infection.
Recombinant protein yields were comparable to or higher than those of High Five cells. The tested products were secreted alkaline phosphatase (SEAP), β-galactosidase (β-gal), the adenovirus penton-based virus-like particle ADDomer, and the malaria vaccine candidate PfRipr5.
The authors describe the new lines as fully traceable and virus-free, with an enhanced biosafety profile. They state that this potentially increases the lines' suitability for regulated biomanufacturing, and that the lines can serve as platforms for high-level recombinant protein production in both research and industrial applications biomedcentral.com
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The study reports results from laboratory characterization of the cell lines; the source material does not describe use of the new lines in commercial manufacturing.
