Site-specific biotinylation of human myeloid differentiation protein 88 in Drosophila melanogaster Schneider 2 cell cytoplasm

Effect of hypothermic temperatures on production of rabies virus glycoprotein by recombinant Drosophila melanogaster S2 cells cultured in suspension

Aiming at maximizing the production of transmembrane rabies virus glycoprotein (rRVGP), the influence of hypothermic temperature on a recombinant Drosophila melanogaster S2 cell culture in Sf-900II medium was investigated. Cell growth and rRVGP production were assessed at 4 culture temperatures in Schott flasks: 16, 20, 24 and 28 °C. The maximum specific growth rates μ(max) were, respectively: 0.009, 0.019, 0.038 and 0.035 h(-1), while the maximum rRVGP levels C(max)(rRVGP) were: 0.075, 2.973, 0.480 and 1.404 mg L(-1). The best production temperature (20 °C) was then tested in a bioreactor with control of pH and dissolved oxygen in batch and fed-batch modes. In the batch culture, μ(max) and C(max)(rRVGP) were 0.060 h(-1) and 0.149 mg L(-1) at 28 °C and 0.026 h(-1) and 0.354 mg L(-1) at 20 °C, respectively. One batch-culture experiment was carried out with adaptation of the cells by the temperature falling in steps from 20 °C to 16 °C, so that μ(max) fell from 0.023 to 0.013 h(-1), while C(max)(rRVGP) was improved to 0.567 mg L(-1). In the fed-batch mode at 20 °C, μ(max) was 0.025 h(-1) and C(max)(rRVGP) was 1.155 mg L(-1). Taken together, these results indicate that the best strategy for optimized rRVGP production is the culture at hypothermic temperature of 20 °C, when μ(max) is kept low and with feeding of limitant aminoacids.

Drosophila melanogaster S2 cells for expression of heterologous genes: From gene cloning to bioprocess development

In the present review we discuss strategies that have been used for heterologous gene expression in Drosophila melanogaster Schneider 2 (S2) cells using plasmid vectors. Since the growth of S2 cells is not dependent on anchorage to solid substrates, these cells can be easily cultured in suspension in large volumes. The factors that most affect the growth and gene expression of S2 cells, namely cell line, cell passage, inoculum concentration, culture medium, temperature, dissolved oxygen concentration, pH, hydrodynamic forces and toxic metabolites, are discussed by comparison with other insect and mammalian cells. Gene expression, cell metabolism, culture medium formulation and parameters involved in cellular respiration are particularly emphasized. The experience of the authors with the successful expression of a biologically functional protein, the rabies virus glycoprotein (RVGP), by recombinant S2 cells is presented in the topics covered.