Many vaccines currently given to humans are produced using animal products. This includes the use of media formulations supplemented with bovine serum. The use of animal products in vaccine production carries the risk of introducing infectious agents. While bovine serum is effective in supporting the growth of vaccine production cell lines such as Vero, there are many problems and risks from its use. Bovine serum has the potential to carry prions (mad cow disease). Recently, preparations of Rota Teq™ were found to be contaminated with porcine circovirus (1, bottom)-presumably from the use of animal products during production. To reduce the risk of transmission of infectious agents, irradiated serum is used for vaccine production; however, this adds additional costs. In addition to the safety risks, serum is also undefined, variable in performance from lot-to-lot, and can be a non-human contaminant in vaccine preparations (1, 2).
Current commercial vaccine media do not require the use of bovine serum, but these media have limitations as well. Undefined protein hydrolysates are included in these media in order to support the serum-free growth of cells. The use of hydrolysates can introduce lot-to-lot variability in performance and other potential complications. These media do not have a defined composition. In addition, these media use iron compounds as an iron source to support the growth of cells. The normal physiological carrier for iron is transferrin. As mentioned in a previous blog, iron compounds introduce iron into cells in an unregulated manor. Free iron compounds can introduce oxidative damage to cells.
A superior approach for vaccine production is to use safe, consistent, and defined approaches in vaccine media formulations. The table below summarizes the limitations of current vaccine production media and an ideal vaccine medium approach. An ideal vaccine medium would include the use of recombinant human transferrin for efficient iron delivery and recombinant human albumin to support the robust growth of cells without serum. These animal-free components offer benefits, without the risks and complications of undefined animal products and could be used to create a far superior vaccine media.
|Vaccine Medium (b)||Animal-Free||Defined (a)||No Iron Chelators||Albumin Benefits||Purification Benefits|
|Ideal Vaccine Medium||✔||✔||✔||✔||✔|
|Classical Medium + Serum||✔||✔|
b) Ex-Cell Vero (SAFC) has been discontinued