Comparison of transient and stable expression of foot-and-mouth disease virus capsid proteins in mammalian cells

Abstract

Foot-and-mouth disease is a highly contagious disease that produces severe economic losses in the livestock industry. This disease is being controlled by the use of an inactivated vaccine. However, the use of recombinant empty capsids as a subunit vaccine has been reported to be a promising candidate because it avoids the use of virus in the vaccine production. A plasmid containing the capsid precursor P12A and protease 3C sequences of foot-and-mouth disease virus (FMDV) was constructed and used to compare transient and stable expression in mammalian cells. When BHK-21 cells were transfected with the recombinant vector, protease 3C cleaved the capsid precursor P12A into the structural proteins VP0, VP1 and VP3. A sucrose gradient demonstrated that the structural proteins assembled into different subviral particles. Attempts to generate a stable cell line only allowed isolating low-level-expressing clones, probably due to the effect of protease 3C on the cells. Moreover, the recombinant protein yield achieved in transient expression assays was much higher than the one achieved in stable expression assays. Results indicate that mammalian cells are a good strategy to produce recombinant FMDV subviral particles. However, the alternative approach of transient gene expression in scalable systems should be used instead of the standard method that involves the generation of a stable cell line.

Foot-and-Mouth Disease: Optimization, Reproducibility, and Scalability of High-Yield Production of Virus-Like Particles for a Next-Generation Vaccine

“…However, toxic proteins like protease 3C do not allow the development of stable cell lines. In this context, TGE is a simple and fast technology for the production of recombinant proteins, which was developed to produce mg of proteins for the first steps in clinical trials and thus represents the strategy of choice for mammalian cell expression of toxic proteins ( 24 ). In the case of FMD novel vaccines, TGE has some advantages because the process itself is quite similar to the current production of the inactivated virus but the preparation of viral seeds and infection of cells are replaced by plasmid production and transfection, respectively.…”