Abstract

Background:
Lumpy skin disease virus (LSDV) is an increasingly prevalent pathogen that is of significant worldwide 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 the establishment of effective and scalable vaccine production systems to satisfy both local and global vaccine demands. Vaccine manufacturing has depended on LSDV multiplication in adherent cell cultures, thus constraining large-scale manufacturing.

Aim:
This study aimed to enhance and maximize the productivity of a LSDVon suspension-adapted cell line. VERO cells are anchorage-dependent, and there are currently no commercially available suspension VERO cell lines do not currently exist. 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.

Methods:
A robust small-scale suspension culture system of Vero cells was developed for the efficient propagation of Lumpy Skin Disease Virus (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.

Results:
The adapted cells maintained high viability and proliferation rates in suspension, reaching 1.94×106 cells/mL. Upon infection with LSDV, the suspension-adapted Vero cells supported efficient viral replication, as confirmed by cytopathic effect observation, quantitative PCR, and infectivity titration assays, reaching as high as 6.85 log₁₀ TCID₅₀/mL 96 hr post infection following 9 passages in suspension-adapted Vero cells, and 5.5 log₁₀ TCID₅₀/mL in adherent Vero cells indicating a superior performance of the suspension culture system compared to traditional adherent cultures. 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 our results suggest advantages in terms of process control and culture flexibility, further studies in bioreactors are needed to confirm performance at industrial scales.

Conclusion:
The work reported here is among the first studies demonstrating high-titer LSDV production in suspension-adapted Vero cell culture (up to 7 × 10⁶ TCID₅₀/mL), highlighting its potential as a flexible and efficient platform for future scale-up. Although these results are promising, further studies in bioreactors and process validation are needed to confirm their industrial applicability and regulatory compliance.

Key words: Cell culture; Lumpy skin disease virus; New methods; Vero cells.