Baculovirus production for gene therapy: the role of cell density, multiplicity of infection and medium exchange

• Published in: Applied microbiology and biotechnology Vol. 81; no. 6; pp. 1041 - 1049
• Main Authors: Carinhas, Nuno, Bernal, Vicente, Yokomizo, Adriana Y., Carrondo, Manuel J. T., Oliveira, Rui, Alves, Paula M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2009; Springer; Springer Nature B.V
• Subjects: Animals; Baculoviridae - growth & development; Baculovirus; Batch processes; Biological and medical sciences; Biotechnological Products and Process Engineering; Biotechnology; Cell Count; Cell Culture Techniques - methods; Cell Line; Cells; Culture Media, Serum-Free; Fundamental and applied biological sciences. Psychology; Gene expression; Gene therapy; Genetic Therapy - methods; Infections; Life Sciences; Microbial Genetics and Genomics; Microbiology; Productivity; Proteins; Spodoptera; Spodoptera frugiperda; Studies; Vectors (Biology); Viruses; Sf-9 cells; Medium exchange; Multiplicity of infection; Baculovirus; Gene therapy; Cell density effect; Virus; Infection; Cell therapy; Baculoviridae; Production; Gene therapy . Cell density effect; Sf-9 cells . Multiplicity of infection; Density
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-008-1727-4

One of the major concerns regarding the use of insect cells and baculovirus expression vectors for the production of recombinant proteins is the drop in production observed when infecting cultures at high cell densities; this work attempts to understand this so-called cell density effect in the scope of baculovirus production for gene therapy purposes. A Spodoptera frugiperda insect cell line (Sf-9) was cultured and infected in serum-free medium, and the patterns of production of a recombinant baculovirus expressing the green fluorescent protein (GFP) were analyzed at different cell concentrations at infection (CCIs) and multiplicities of infection (MOIs). The results confirm that a cell density effect on productivity occurs which is dependent on the MOI used, with a high MOI “delaying” the drop in production to higher cell densities. Medium replacement at the time of infection using a high MOI considerably improved baculovirus production, with the different production indicators, namely the titer, specific yield, amplification factor, and time of harvesting, increasing with cell concentration for the CCI range tested. Virus titers as high as 2.6 × 10 10  IP.mL −1 were obtained in cultures infected at 3.5 × 10 6 cells.mL −1 , while the amplification factor was roughly 19 times higher than the highest value obtained without medium exchange.