Smart Scale-Up: Expanding Viral Vectors With Microcarrier Bead Technology

By Heidi Trusheim, Director, Process Development, and Edward Fix, Director, Manufacturing, IDT Biologika

As healthcare professionals continue administering the Pfizer-BioNTech and Moderna mRNA-based COVID-19 vaccines, other companies are actively developing viral vector-based vaccines to combat both coronavirus and other infectious diseases. Unlike mRNA vaccines, viral vector vaccines require living cells for production. However, different viral vectors have distinct cultivation requirements — some can only be grown using adherent cell cultures, while others are compatible with suspension cell cultures. Scaling up adherent cell cultures presents unique challenges for vaccine manufacturers, often requiring innovative technologies to enable safe, efficient, and rapid large-scale production.

One such innovation is microcarrier bead technology, a proven yet relatively recent advancement that allows adherent cells to be imprinted onto carriers. These carriers can then be expanded within single-use bioreactors (SUT reactors), facilitating the scale-up required for both clinical and commercial vaccine production. When paired with well-established cell lines, such as Vero cells, microcarrier beads enable manufacturers to optimize the use of their existing suspension culture equipment, enhancing flexibility and production efficiency.

However, some companies may lack the analytical capabilities needed to thoroughly characterize cell lines that can effectively replicate target viruses at titers high enough for large-scale vaccine production. Others may struggle with securing qualified cell lines that meet regulatory and commercial standards. Partnering with a contract development and manufacturing organization (CDMO) can accelerate early-stage development while reducing costs. But, selecting the right CDMO is critical — companies must ensure their partner possesses the deep process knowledge and technical expertise necessary to apply microcarrier technology and specific cell lines to their unique project requirements.