Behavior of wild-type and transfected S2 cells cultured in two different media.

An animal protein-free medium composed of IPL-41 containing 6 g L(-1) yeastolate ultrafiltrate, 10 g L(-1) glucose, 2 g L(-1) lactose, 5 g L(-1) glutamine, 1% lipid emulsion, and 0.1% Pluronic F-68 was used for producing recombinant proteins in batch mode employing two cell lines, S2AcRVGP2k expressing the G glycoprotein from rabies virus (RVGP) and S2AcHBsAgHy-9C expressing the surface antigen of hepatitis B virus (HBsAg), both obtained from Drosophila melanogaster S2 cells. Growth of wild-type S2 cells was also evaluated in the same medium. Cell behavior in the tested medium was compared to that verified in Sf900 II®. The results show that in shake flasks, S2AcRVGP2k and S2AcHBsAgHy-9C cells reached around 2 × 10(7) cells mL(-1) in both media. In supplemented IPL-41 and Sf900 II® media, S2AcRVGP2k cells produced 367 ng RVGP mL(-1) and 638 ng RVGP mL(-1), respectively, while S2AcHBsAgHy-9C cells correspondently produced 573 ng HBsAg mL(-1) and 322 ng HBsAg mL(-1) in the mentioned media. In stirred tanks, S2AcRVGP2k cells reached 3 × 10(7) cells mL(-1) and produced up to 758 ng RVGP mL(-1). In general, glucose was consumed by cells, while lactate and ammonia were produced.

Antiviral activity of the hemolymph of Lonomia obliqua (Lepidoptera: Saturniidae).

Potent antiviral activity against measles, influenza and polio viruses was observed in the hemolymph of Lonomia obliqua. The antiviral protein responsible for this activity was isolated, purified by gel filtration chromatography using a gel filtration column system (Superdex 75) and further fractionated using a Resource-Q ion exchange column system. Experiments with the purified protein led to a 157-fold reduction (from 3.3+/-1.25 x 10(7) to 2.1+/-1.5 x 10(5) TCID(50)mL(-1)) in measles virus production and a 61-fold reduction (from 2.8+/-1.08 x 10(9) to 4.58+/-1.42 x 10(7)mL(-1)) in polio virus production. Heating and freezing seem to have no influence over its antiviral activity. Also, the protein does not display virucidal activity and does not act on receptors on the cell membrane. The observations suggest an intracellular mechanism of action and that the protein may act as a constitutive agent that affects the innate antiviral immune response.

Study of kinetic parameters for the production of recombinant rabies virus glycoprotein.

Gene expression in insect cells is an advantageous system for recombinant protein production, mainly because of its capacity to produce complex proteins with correct post-translational modifications. Recently, we identified and purified a protein from Lonomia obliqua hemolymph able to increase the production of rabies virus glycoprotein, expressed in Drosophila melanogaster cells, by about 60%. In this work, the kinetic parameters for cell growth and recombinant rabies virus glycoprotein production were determined in cultures of transfected Drosophila melanogaster Schneider 2 (S2) cells expressing recombinant rabies virus glycoprotein (rRVGP), enriched and non-enriched with the hemolymph of Lonomia obliqua (Hb). The highest concentration of rRVGP was achieved at the beginning of the culture enriched with Hb, indicating that the cells produce greater amounts of rRVGP per cell (specific rRVGP concentration) at the early exponential growth phase. After day 8, a decrease in the concentration of rRVGP (ng/mL) was observed, probably due to protein decomposition. The average specific rRVGP production rate (mu(rRVGP)) was 30 ng rRVGP/10(7)cell.day, higher than that observed in the non-enriched culture.

Enhancing effect of a protein from Lonomia obliqua hemolymph on recombinant protein production.

Gene expression in animal cells allows large scale production of proteins used for either structure and function studies or therapeutic purposes. Maximizing recombinant protein production is necessary to optimize cell growth and protein expression. Some studies have demonstrated the presence of pharmacologically active substances in insect hemolymph. In this work, we have identified and purified a protein from Lonomia obliqua hemolymph able to increase the production of the rabies virus glycoprotein, expressed in Drosophila melanogaster S2 cells, by about 59%.