# Virus-free Tn5 insect cell lines match commercial High Five protein yields in serum-free culture

- Published: 2026-11-13 09:07 UTC
- Section: Life & Health › Biotechnology
- Tags: BTI-TN-5B1-4, High Five cells, Trichoplusia ni, virus-free cell lines, Tn5 Cell Line Virus, Bombyx mori macula-like virus, Sf9 co-culture, recombinant protein production, serum-free suspension culture, biomanufacturing
- URL: https://realtech.media/news/rt-a0c5dc5ac7b88439dffa750d_virus_free_tn5/

**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.**

![Virus-free Tn5 insect cell lines match commercial High Five protein yields in serum-free culture](https://realtech.media/media/2026/11/45d8bf365e2ac26a.jpg)
*Gerit Linneweber, Wikimedia Commons, CC BY 2.0*

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 [1].

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 [1].

## 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) [1].

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 [1].

## 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 [1].

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 [1].

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 [1].

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.

## Sources

1. [BMC Biotechnology](https://doi.org/10.1186/s12896-026-01246-7)
2. [bioengineer.org](https://bioengineer.org/virus-free-insect-cell-lines-match-commercial-high-five-protein-yields)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-a0c5dc5ac7b88439dffa750d_virus_free_tn5/