Insect Cell Culture Medium Supplementation with Fetal Bovine Serum and Bovine Serum Albumin: Effects on Baculovirus Adsorption and Infection Kinetics

The effects of insect cell culture medium supplementation with FBS were investigated. BSA was found to be the factor responsible for the increased baculovirus infection rate ofFBS-supplemented cultures in a concentration-dependent form up to 25 g L^-1 Lower rates of baculovirus binding to cells were observed with FBS- and BSAsupplemented cultures compared with infections carried out in serum-free media. Virus attachment constants were found to depend on medium matrix composition. An efficiency factor dependent on the medium matrix composition was introduced to account for these effects, and a mathematical model was developed to describe the virus-cell interactions. It was shown that BSA acts by minimizing the nonspecific virus binding leading to an increased cell infection rate. Cell specific Porcine paruouirus virus-like particles (PPV-VLPs) expression was unaffected by medium supplementation pointing out that BSA and/or FBS affects mainly the initial phase of the baculovirus infection cycle. Implications for process definition are discussed.