title: Virus-like particle production at low multiplicities of infection with the baculovirus insect cell system.
abstract: The baculovirus insect cell expression system (BEVS) was used for the production of self-forming Porcine parvovirus-like particles (VLPs) in serum-free medium. A low multiplicity of infection (MOI) strategy was used to overcome an extra virus amplification step, undesirable in industrial production, and to minimize the virus passage effect. It was confirmed that the time of infection (TOI) and MOI are dependent variables. Higher cell densities were obtained at low MOIs, keeping a constant TOI; however, both volumetric and specific productivities were lower. In synchronous infection, at high MOI, the specific productivity decreased when the cells were infected in the late phase of growth. Product degradation due to cell lysis strongly influenced the optimal time of harvest (TOH). Time of harvest was found to be highly dependent on the MOI, and a direct relationship with the cell yield was obtained. Analysis of the culture medium reveals that glutamine depletion occurs in the late phase of the growth. Supplementation of glutamine to uninfected cell cultures resulted in an increased cell yield. Its addition to cultures infected in the middle phase of the growth curve was also able to restore the productivity levels, but addition to cells in their stationary phase caused no observable effect on product expression. The study clearly shows that for a specific TOI it is not obvious what the correct MOI should be to obtain the best volumetric productivity.
authors.affiliation: Instituto de Biologia Experimental e Tecnológica/Instituto de Tecnologia Química e Biológica IBET/ITQB, Apartado 12, P-2781-901 Oeiras, Portugal.
authors.forename: Luis
authors.initials: L
authors.lastname: Maranga
authors.forename: Tiago F
authors.initials: TF
authors.lastname: Brazão
authors.forename: Manuel J T
authors.initials: MJ
authors.lastname: Carrondo
mesh_terms: D000465:Algorithms; D000818:Animals; D016367:Baculoviridae / Q000254:growth & development* / Q000378:metabolism; D036022:Capsid Proteins / Q000378:metabolism; D018929:Cell Culture Techniques; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004307:Dose-Response Relationship, Radiation; D005947:Glucose / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D005973:Glutamine / Q000494:pharmacology; D019344:Lactic Acid / Q000494:pharmacology; D028323:Parvovirus, Porcine / Q000254:growth & development / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D018411:Spodoptera / Q000166:cytology / Q000254:growth & development / Q000821:virology*; D010948:Viral Plaque Assay; D014771:Virion / Q000254:growth & development*; D014776:Virus Cultivation; D014779:Virus Replication
chemical_list: D036022:Capsid Proteins; D011994:Recombinant Proteins; C095548:capsid protein VP2, parvovirus B19; D005973:Glutamine; D019344:Lactic Acid; D018698:Glutamic Acid; D005947:Glucose