This Guideline, coming into effect on 12 February 2012, lays down the quality recommendations for cells used to isolate candidate influenza vaccine viruses, the conditions under which the viruses are isolated and the subsequent passage of the viruses until the manufacturer’s Master Seed is prepared under GMP conditions.
Manufacturers of cell-derived vaccine typically use the recommended egg-derived candidate vaccine virus to derive their seed virus. Research indicates, that there are phenotypic changes of human influenza virus when they are adapted to grow in eggs. It can't be ruled out, that this might include changes in antigenicity or immunogenicity. Viruses isolated from mammalian cell cultures do not appear to undergo these changes. Thus a cell-isolated virus may be more clinically relevant for vaccine than an egg isolate. Many vaccine manufacturers wish by those reasons, to use non-egg adapted viruses which are antigenically closer to the wild type virus. The available cells in use by National Influenza Centres and WHO Collaborating Centres for virus isolation are not qualified/validated for use in deriving a candidate vaccine virus and so currently only egg-isolated viruses are taken forward as vaccine candidates.
An influenza virus isolated on cell culture could be used to derive a seed virus for either a cell culture or an egg vaccine production process for the manufacture of inactivated or live attenuated influenza vaccines. Thus, the scope of this document is to provide guidance for the isolation on cell culture of any potential influenza vaccine virus intended for cell culture or egg-based influenza vaccine manufacture. It should be reminded however that influenza viruses used in vaccines should also follow the recommendations published by the WHO on this matter.
For further information please see the "Guideline on quality aspects on the isolation of candidate influenza vaccine viruses in cell culture".
Please also pay attention to ECA's conference "Vaccines and Biologics" on 22 and 23 November in Dessau, Germany, including a site visit at IDT's manufacturing site.
Axel H. Schroeder
CONCEPT HEIDELBERG (a service provider entrusted by the ECA Foundation)