Bioreactor production of rVSV-vectored vaccines in Vero cell suspension cultures

Abstract

The Vero cell line is the most used continuous cell line in viral vaccine manufacturing. This adherent cell culture platform requires the use of surfaces to support cell growth, typically roller bottles or microcarriers. We have recently compared the production of rVSV-ZEBOV on Vero cells between microcarrier and fixed-bed bioreactors. However, suspension cultures are considered superior with regards to process scalability. Therefore, we further explore the Vero suspension system for rVSV-vectored vaccine production. Previously, this suspension cell line was only able to be cultivated in a proprietary medium. Here, we expand the adaptation and bioreactor cultivation to a serum-free commercial medium. Following small scale optimization and screening studies, we demonstrate bioreactor productions of highly relevant vaccines and vaccine candidates against Ebola virus disease, HIV and COVID-19 in the Vero suspension system. rVSV-ZEBOV, rVSV-HIV and rVSVInd-msp-SF-Gtc can replicate to high titers in the bioreactor, reaching 3.87 × 107 TCID50/mL, 2.12 × 107 TCID50/mL and 3.59 × 109 TCID50/mL, respectively. Further, we compare cell specific productivities, and the quality of the produced viruses by determining the ratio of total viral particles to infectious viral particles

Application of bioreactor technology for cell culture-based viral vaccine production: Present status and future prospects

“…Frontiers in Bioengineering and Biotechnology frontiersin.org suitable for infection than MDCK, with a cell density of 1.02 × 10 6 cells/mL, a maximum infection titer of 3.87 × 10 7 TCID 50 /mL, a cell specific productivity was 37.9 TCID 50 /cell, and the ratio of total virus particles to infected particles of 282 VG/TCID 50 . Under similar culture environment conditions, with the improvement of the bioreactor, the yield and infection titer of rVSV-ZEBOV increased significantly (Kiesslich et al, 2021).…”

“…Research on a SARS-CoV-2 vaccine based on rVSV vector is also ongoing (Henao-Restrepo et al, 2015). Kiesslich et al compared the production of rVSVInd-msp-sf-Gtc in MDXK medium and IHM03 medium respectively (Kiesslich et al, 2021). They grew Vero cells in MDXK medium and provided 31 °C, pH 7.2, dissolved oxygen (DO) in a 50% culture environment to achieve an optimal cell density of 1.02 × 106 cells/mL.…”

“…They grew Vero cells in MDXK medium and provided 31 °C, pH 7.2, dissolved oxygen (DO) in a 50% culture environment to achieve an optimal cell density of 1.02 × 106 cells/mL. At 48hpi, the MOI was 0.01, the infection titer was 3.59 × 10 9 TCID50/mL, and genomic titer was 2.13 × 1010 viral genome (VG)/mL (Kiesslich et al, 2021).…”