Stability of recombinant baculoviruses for biopharmaceutical applications in chemically defined medium

Insect cell-baculovirus expression vector systems (IC-BEVS) are valuable tools in pharmaceutical bioprocesses for producing complex proteins like immunogenic virus-like particles. In this context, standardization is key to guarantee consistency in process yield, productivity, and product quality attributes. The study investigates the nine-month stability of the main biotechnological input used in IC-BEVS, the recombinant baculovirus vectors produced in chemically defined medium. Viral titer (pfu/mL), zeta potential (mV), and mean hydrodynamic particle size (μm), were employed to assess viral inactivation under eight combinations of generation and storage conditions. First-order, Weibull, and biphasic models were applied to describe viral decay. The critical parameters (factors) analyzed were the size of the heterologous gene inserted (719 and 1621 bp), storage temperature (- 80 and 1.5 °C), and infection time used for baculovirus batch generation (48 or 72 h post-infection). They were mainly explored according to a two-level factorial design (2³). The primary quality attribute evaluated in this study was the one-log₁₀ decay time of the viral titer (td), which exhibited an overall mean value of 80 days across eight batches. The biphasic model best fits the dispersion of the viral titer data collected over the assessed time in all considered combinations of factors and was employed to find significant factors over td values. Gene size was the only factor with a statistically significant effect on viral titer decay; additionally, the study indicates the occurrence of particle aggregation over the course of the analysis.