Recombinant rabies virus glycoprotein synthesis in bioreactor by transfected Drosophila melanogaster S2 cells carrying a constitutive or an inducible promoter

Abstract S2 cell populations (S2AcRVGP2K and S2MtRVGP-Hy) were selected after transfection of gene expression vectors carrying the cDNA encoding the rabies virus glycoprotein (RVGP) gene under the control of the constitutive (actin) or inductive (metallothionein) promoters. These cell populations were cultivated in a 1 L bioreactor mimicking a large scale bioprocess. Cell cultures were carried out at 90 rpm and monitored/controlled for temperature (28 °C) and dissolved oxygen (10 or 50% air saturation). Cell growth attained ∼1.5–3 × 10 7  cells/mL after 3–4 days of cultivation. The constitutive synthesis of RVGP in S2AcRVGP2K cells led to values of 0.76 μg/10 7 cells at day 4 of culture. The RVGP synthesis in S2MtRVGP-Hy cell fraction increased upon CuSO 4 induction attaining specific productivities of 1.5–2 μg/10 7 cells at days 4–5. RVGP values in supernatant as a result of cell lysis were always very low (