Development of a suspension-based vero cell culture platform for the efficient propagation of lumpy skin disease...

Lumpy skin disease virus (LSDV) is an increasingly prevalent pathogen of significant global concern. It is indigenous to Africa and the Middle East and has recently spread to Europe and Asia. Vaccine-based control programs represent the most effective preventive strategy for disease management. The extraordinary worldwide dissemination of the virus necessitates establishing effective, scalable vaccine production systems to meet both local and global vaccine demand. Vaccine manufacturing has depended on LSDV multiplication in adherent cell cultures, thus constraining large-scale manufacturing.

This study aimed to enhance and maximize the productivity of an LSDV on a suspension-adapted cell line. VERO cells are anchorage-dependent, and there are currently no commercially available suspension VERO cell lines. The creation of our customized cells constitutes a singular R&D investment. Vero cells were adapted for suspension growth to facilitate subcultivation, enhance process scalability, and reduce production costs.

A robust small-scale suspension culture system of Vero cells was developed for the efficient propagation of LSDV. A preliminary step for industrial production in bioreactors, with optimized passage time and initial cell density, along with other factors such as cell density, medium composition, and agitation rates.

The modified cells exhibited remarkable viability and proliferation rates in suspension, reaching 1.94 × 10⁶ cells/ml. Suspension-adapted Vero cells efficiently replicated LSDV, as shown by cytopathic effect observation, quantitative polymerase chain reaction, and infectivity titration assays. After nine passages, suspension-adapted Vero cells reached 6.85 log₁₀ tissue culture infectious dose (TCID₅₀)/ml 96 hours post infection, compared to 5.5 log₁₀in adherent cells. The study demonstrated that LSDV productivity was significantly influenced by a multiplicity of infection of 0.1, a viable cell density of 5.8 × 10⁵ cells/ml, and adequate nutritional supplementation. These findings confirm that suspension-adapted Vero cells offer a promising and potentially scalable platform for the production of LSDV vaccine. Although the obtained results suggest advantages in terms of process control and culture flexibility, further studies in bioreactors are needed to confirm performance at industrial scales.

This study shows high-titer LSDV production in suspension-adapted Vero cell culture (up to 7 × 10⁶TCID₁₀/ml), indicating its potential for future scale-up. These findings are intriguing, but bioreactor studies and process validation are needed to confirm industrial applicability and regulatory compliance.