Efficient Serum-Free Rabies Virus Propagation Using BSR and Vero Cell Lines: A Comparative Evaluation of BioNOC II® Macrocarriers in the BelloStage™-3000 Bioreactor Versus Conventional Microcarriers

The rabies virus remains a significant public health threat, particularly in regions with limited access to vaccination. This study shows that the BelloStage™-3000 bioreactor, operating on the "Tide Motion" principle, in combination with BioNOC^® II macrocarriers, ensures highly efficient rabies virus cultivation in BSR and Vero cells grown in serum-free OptiPRO™ SFM medium. This system supports effective cell attachment, formation of a dense and metabolically active cell layer, and reduces microbial contamination risks associated with serum-containing media. For comparison, rabies virus cultivation was also performed on Cytodex 1 and Cytodex 3 microcarriers in spinner flasks. The use of the BelloStage™-3000 bioreactor system with BelloCell™ 500A disposable vials and BioNOC II^® macrocarriers resulted in significantly higher virus titers compared to traditional Cytodex 1 and Cytodex 3 microcarrier culture systems. Thus, in the BSR cell culture, the maximum virus titer reached 5.6 × 10⁸ FFU/mL by day 4 of cultivation, which exceeded the titers obtained on Cytodex 1 and Cytodex 3 microcarriers by about 19.3-fold and 15.3-fold, respectively. A similar trend was observed for the Vero cell line: the peak titer was 2.0 × 10⁸ FFU/mL by day 5 of culturing, which was higher than the values obtained on Cytodex 1 and Cytodex 3 by about 14.0-fold and 9.6-fold, respectively. These findings demonstrate that the integrated use of BioNOC^® II macrocarriers, the BelloStage™-3000 bioreactor, and a serum-free medium provides a scalable, reproducible, and biosafe platform for rabies virus production, offering substantial advantages over traditional microcarrier-based systems.