The ExpreS2 Platform

The ExpreS2 Platform

The Company’s ExpreS2 platform has been used successfully for the development and production of hard-to-express proteins for over a decade. It has a great track record, with over 500 proteins expressed and a success rate above 90 percent. Additional advantages include a rapid delivery process of 3-6 months, and a high batch-to-batch consistency.

The platform is used in ExpreS2ion’s two most valuable development programs, the ABNCoV2 COVID-19 vaccine and the Company’s own ES2B-C001 HER2 breast cancer vaccine programme, as well as in several Malaria vaccine partner projects and the influenza vaccine project developed within the INDIGO consortium. The platform is also used in ExpreS2ion’s CRO services, which will be increasingly used to drive value generation in the company’s pipeline development projects going forward.

In addition to its current advantages, the ExpreS2 platform is also in the process of being upgraded with unique and genetically engineered cell lines, such as the HighMan-S2™. With these cell lines, the proteins expressed are given improved characteristics such as the facilitation of higher immunization levels compared to regular versions of the same proteins.

ExpreS2 Value-Add


1) Significantly less costly and time consuming than alternative methods, which is an important competitive advantage, considering time-to-market and patent expiry. It also makes the platform particularly valuable for the development of diagnostics and vaccines in epidemic or pandemic situations where speed is of the essence.

2) Generates higher yields, i.e. amount of protein per manufacturing batch, compared to competing systems.

3) Provides homogeneous manufacturing batches, a requirement in pharmaceutical development. The platform includes the Company’s patented expression vectors which were developed, among other things, to make it possible for the cells to generate higher yields.

4) Since 2019 the Company’s offering to the biopharma sector includes glyco-engineered S2 cell lines under the GlycoX-S2™ brand. This allows for functional modification, e.g. by enhancing immunogenicity or improving pharmacokinetics.


The ExpreS2 Kit

The ExpreS2 Kit

For biotechnology companies eager to use our ExpreS2 technology in their own projects, ExpreS2ion has put together a complete ExpreS2 kit.

The ExpreS2 platform is a perfect addition to the standard toolbox available to researchers when working with protein expression. Its strong and flexible feature set has been proven to advance even the most challenging projects in various research and development areas.

The ExpreS2 kit is globally available and includes the following:

  • ExpreS2 plasmids
  • ExpreS22 cells
  • ExpreS2 transfection reagent, TRx5s
  • Culture media for S2 cells
  • Plasmid maps and protocols for use

The ExpreS2 kit can be ordered from ExpreS2ion for technology assessment within a set time period through a material transfer agreement (MTA). Upon achieving successful results, the next step is to sign a license agreement for further use of the ExpreS2 platform.

For more information on how to order the ExpreS2 kit, contact us.



Glycosylation in S2 cells is very similar to that of SF9, Sf21, and High Five cells. The nature of Drosophila N-linked glycosylation is less complex than mammalian glycosylation – it is generally of the paucimannose type and is not trimmed and sialylated.

O-linked glycosylation is similar, although not identical, to that obtained in mammalian cells. However, human glycosylation profiles are difficult to obtain, also glycosylation from CHO and HEK293 differ from human glycosylation. Human O-glycosylation can be divided into N-acetylGalactosamine linked (mucin type), N-acetylGlucosamine lined (O-GlcNAc type) and xylose linked (proteoglycans) families. The most abundant form is the mucin type, while O-GlcNac has only been found for cytoplasmic and nuclear proteins, the proteoglycans are of less interest here.

In CHO cells, O-glycosylation results in terminally sialated mucin type glycans, with a low percentage core-1 structure (T-antigen) reported. In Drosophila S2, cell O-glycosylation is less complex than in human or mammalian cells. Unlike human proteins, O-GlcNAc has been found on an external protein. It appears that O-GlcNAc can occur in specific cases and are linked to the regulation of the protein, in this case the Notch receptor. However, mucin type glycosylation is the dominant O-glycosylation type in S2 cells and has been shown to be of the Tn-antigen (GalNAcalpha-Ser/Thr) and the core-1 structure (T-antigen) (Galbeta1-3GalNAcalpha-Ser/Thr) forms.

More information on glycosylation insert can be found here.

More information on S2 cells and glyco-engineered S2 cell lines can be found here.


  • 10 µg/mL Inhibits bacterial protein synthesis.


  • 100 U/mL Penicillin Inhibits bacterial cell wall synthesis.
  • 100 µg/mL Streptomycin Inhibits bacterial protein synthesis.

Amphotericin B

  • Fungizone 0.25 µg/mL Binds sterols and interferes with membrane permeability.

No, and in fact CO2 is toxic to S2 cells.

More information about S2 cells and how easy they are to grow can be found here

Humidification is only necessary for monolayer cultures in tissue culture plates. Plates can also be wrapped in parafilm and put in a box with a beaker with water. For other S2 culture modes in incubators, humidification is not necessary.

More information about S2 cells and how easy they are to grow can be found here.

The accumulating dogma seems to indicate that CMV expresses in a number of cell types. For example, CMV drives expression in frog oocytes. The following articles discuss the CMV promoter in S2 cells. One provides evidence that it works well, and one finds that it does not. Indicates that CMV promoter does not work in Kc1 and S2 cells: Gene 1997 Apr 1;188(2):183-90 Pfeifer TA, Hegedus DD, Grigliatti TA, Theilmann DA Baculovirus immediate-early promoter-mediated expression of the Zeocin resistance gene for use as a dominant selectable marker in dipteran and lepidopteran insect cell lines. Demonstrates that CMV promoter does work in Drosophila cells: Nucleic Acids Res 1987 Mar 11;15(5):2392 Sinclair JH. The human cytomegalovirus immediate early gene promoter is a strong promoter in cultured Drosophila melanogaster cells.

Yes. D. Mel is short for Drosophila melanogaster, which is the proper species name for the cells commonly referred to as Schneider S2 cells or just S2 cells.

We recommend 110 rpm for shake flasks with or without baffles.

S2 cells can be grown at 23-27 °C but they will recover after excursions up to 37 °C. However, we routinely grow our cells at 25 °C.

More information baout S2 cells and how easy they are to grow can be found here

Yes, bBaculovirus can infect S2 cells., Hhowever, the virus will not replicate in the infected cells and will not be able to infect subsequent cells. No high-titreer stocks can be generated from S2 cells.

Some of the advantages are: a more homogeneous glycosylation profile; better reproducibility between manufacturing runs; several options for cultivation modes, such as perfusion that allows for long cultivation times with daily harvests; no cell lysis due to establishment of stable cell lines, resulting in lower levels of contaminating host cell proteins.

The baculovirus system is a lytic system (the cells lyse upon infection with a recombinant bBaculovirus containing the gene of interest) while the S2 platform is stable insect cell expression. Insect cells are transfected with an expression vector, followed by selection and screening of polyclonal or monoclonal high-producers.