title: Production of the baculovirus-expressed dengue virus glycoprotein NS1 can be improved dramatically with optimised regimes for fed-batch cultures and the addition of the insect moulting hormone, 20-Hydroxyecdysone.
abstract: A perennial problem in recombinant protein expression is low yield of the product of interest. A strategy which has been shown to increase the production of baculovirus-expressed proteins is to utilise fed-batch cultures. One disadvantage of this approach is the time-consuming task of optimising the feeding strategy. Previously, a statistical optimisation routine was applied to develop a feeding strategy that increased the yield of beta-Galactosidase (beta-Gal) by 2.4-fold (Biotechnol. Bioeng. 59 (1998) 178). This involves the single addition of nutrient concentrates (amino acids, lipids, glucose and yeastolate ultrafiltrate) into Sf 9 cell cultures grown in SF 900II medium. In this study, it is demonstrated that this optimised fed-batch strategy developed for a high-yielding intracellular product beta-Gal could be applied successfully to a relatively low-yielding glycosylated and secreted product such as the dengue virus glycoprotein NS1. Optimised batch infections yielded 4 microg/ml of NS1 at a peak cell density of 4.2 x 10 (6) cells/ml. In contrast, optimised fed-batch infections exhibited a 3-fold improvement in yield, with 12 microg/ml of NS1 produced at a peak cell density of 11.3 x 10 (6) cells/ml. No further improvements in yield were recorded when the feed volumes were doubled and the peak cell density was increased to 23 x 10 (6) cells/ml, unless the cultures were stimulated by the addition of 4 microg/ml of 20-Hydroxyecdysone (an insect moulting hormone). In this case, the NS1 yield was increased to 20 microg/ml, which was nearly 5-fold higher than optimised batch cultures.
authors.affiliation: Department of Chemical Engineering, The University of Queensland, Qld St Lucia 4072, Australia. lesliec@cheque.uq.edu.au
authors.forename: Leslie C L
authors.initials: LC
authors.lastname: Chan
authors.forename: Paul R
authors.initials: PR
authors.lastname: Young
authors.forename: Cheryl
authors.initials: C
authors.lastname: Bletchly
authors.forename: Steven
authors.initials: S
authors.lastname: Reid
mesh_terms: D000818:Animals; D002460:Cell Line; D003470:Culture Media; D003716:Dengue Virus / Q000235:genetics*; D004441:Ecdysterone / Q000378:metabolism; D005822:Genetic Vectors; D017924:Nucleopolyhedroviruses / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D018411:Spodoptera; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D003470:Culture Media; C079340:NS1 protein, Dengue virus type 2; D011994:Recombinant Proteins; D017361:Viral Nonstructural Proteins; D004441:Ecdysterone; D001616:beta-Galactosidase