title: Viral antigen production in cell cultures on microcarriers Bovine parainfluenza 3 virus and MDBK cells.
abstract: Viral antigens can be obtained from infected mammalian cells cultivated on microcarriers. We have worked out parameters for the production of bovine parainfluenza 3 (PI-3) virus by Mandin-Darby Bovine Kidney (MDBK) cells cultivated on Cytodex 1 microcarriers (MCs) in spinners flasks and bioreactor using fetal bovine serum (FBS) supplemented Eagle minimal essential medium (Eagle-MEM). Medium renewal during the cell culture was shown to be crucial for optimal MCs loading (>90% MCs with confluent cell monolayers) and cell growth (2.5 x 10(6)cells/mL and a micro(x) (h(-1)) 0.05). Since cell cultures performed with lower amount of MCs (1g/L), showed good performances in terms of cell loading, we designed batch experiments with a lower concentration of MCs in view of optimizing the cell growth and virus production. Studies of cell growth with lower concentrations of MCs (0.85 g/L) showed that an increase in the initial cell seeding (from 7 to 40 cells/MC) led to a different kinetic of initial cell growth but to comparable final cell concentrations ((8-10)x10(5)cells/mL at 120 h) and cell loading (210-270 cells/MC). Upon infection with PI-3 virus, cultures showed a decrease in cell growth and MC loading directly related to the multiplicity of infection (moi) used for virus infection. Infected cultures showed also a higher consumption of glucose and production of lactate. The PI-3 virus and PI-3 antigen production among the cultures was not significantly different and attained values ranging from, respectively, 7-9 log(10) TCID(50)/mL and 1.5-2.2 OD. The kinetics of PI-3 virus production showed a sharp increase during the first 24h and those of PI-3 antigen increased after 24h. The differential kinetics of PI-3 virus and PI-3 antigen can be explained by the virus sensitivity to temperature. In view of establishing a protocol of virus production and based on the previous experiments, MDBK cell cultures performed under medium perfusion in a bioreactor of 1.2L were infected and the PI-3 virus production in 12L attained 12 log(10) TCID(50). Other than establishing a protocol for PI-3 production in MDBK cell cultures on Cytodex 1, the experiments are proposed as a basis for approaching the development of a virus production protocol in mammalian cells cultivated on microcarriers in bioreactors.
authors.affiliation: Laboratório de Imunologia Viral, Instituto Butantan, Av. Vital Brasil 1500, 05503-900 São Paulo, Brazil.
authors.forename: M M
authors.initials: MM
authors.lastname: Conceição
authors.forename: A
authors.initials: A
authors.lastname: Tonso
authors.forename: C B
authors.initials: CB
authors.lastname: Freitas
authors.forename: C A
authors.initials: CA
authors.lastname: Pereira
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000096:biosynthesis* / Q000378:metabolism; D019149:Bioreactors; D002417:Cattle; D018929:Cell Culture Techniques / Q000295:instrumentation* / Q000379:methods; D029101:Parainfluenza Virus 3, Bovine / Q000254:growth & development*; D014407:Tumor Cells, Cultured / Q000821:virology*; D014776:Virus Cultivation / Q000295:instrumentation* / Q000379:methods; D014779:Virus Replication / Q000502:physiology*
chemical_list: D000956:Antigens, Viral