Bryan Griffiths

Animal Cell Technology

Classical rabies vaccine strains (genotype 1) protect inefficiently against rabies-related lyssaviruses (other genotypes) and in particular against the Mokola virus (genotype 3). DNA vaccine modem approach was used to produce Mokola valency. Purified Plasmid vector was injected into each anterior tibialis muscle of BALB/c mice. It appeared that the Mokola DNA vaccine has induced a sustained level of VNAb, a T helper cell response and confered protection against Mokola virus challenge. Therefore, it seems that the DNA vaccine approach is a very promising technology, which needs further investigations for a possible application.

Can cell culture medium costs be reduced? Strategies and possibilities

Abstract The complex media needed for the culture of animal cells is expensive and is one factor that puts cell culture at a great economic disadvantage compared with other microbial systems. Viewing these costs in a proper perspective shows that this disadvantage is often exaggerated, but even so there are several ways in which significant savings can be made.

DNA fingerprinting--a valuable new technique for the characterisation of cell lines.

DNA fingerprinting is an important new development for the authentication of cell lines. Multilocus methods such as those developed by Alec Jeffreys provide information on a wide range of genetic loci throughout the human genome and thus give a useful genetic “snap-shot” of a cell culture. Our work has shown that Jeffreys multilocus fingerprinting method can be applied to cell lines from a wide range of animals including reptiles, birds, fish and diverse mammals. It can also differentiate very closely related cell lines including those from the same mouse strain. Routine fingerprint analysis has enabled an unprecedented level of confidence in the consistency of cell stocks. Our results demonstrate that this straightforward method represents a powerful and readily interpreted system for cell authentication and exclusion of cross-contamination.

Animal cells — the breakthrough to a dominant technology

Animal Cell Culture has become a dominant technology in the past few years due to a change in attitudes as much as to development in techniques. Whilst manufacturers were locked into the use of human diploid (HD) or primary cells by current licencing regulations, animal cell culture was never going to be a first choice production method. Manufacturers of human biologicals had always looked with envy at their veterinary counterparts using BHK cells in 8000 L stirred tanks to produce FMDV vaccine, and hoped that one day they could use a similar methodology. This moment has now arrived as 3 major biologicals manufactured from heteroploid, tumour-derived or recombinant, cell lines have been licenced in the past few years (Table 1). In addition, there are other products with limited national licences, or in clinical trial. The reasons for products from such cell lines being accepted include major improvements in purification technology, and increased sensitivity of assay techniques for dangerous contaminants (e.g., DNA, retroviruses). Thus the process and final product can be properly validated. The acceptance of more realistic standards (e.g. for DNA) has also greatly helped. This breakthrough which has broken the dogma of only using primary and HD Cells has completely opened up the horizons for future developments in animal cell biotechnology. However important it has not been the sole development over the past few years (Table 2). Scale-up to 8000 L bioreactors for interferon, 2000 L. for monoclonal antibody, and 4000 L for microcarrier culture, has proven that cell culture can be operated at the industrial plant level. A further example of scale-up capability is that the total worldwide production of MAB in 1980 was lg, in 1988 this was in the region of 50 kg or higher. Other developments that have proceeded successfully are the ability to grow cells to high density (50-fold increase in unit cell density), and in serum-free, low-protein media. The last two factors have considerably reduced the advantage gap that bacterial systems had over animal cells in terms of productivity and culture costs.

Adaptation of BHK cells producing a recombinant protein to serum-free media and protein-free medium

In this work a recombinant BHK21 clone producing a fusion protein with potential application in tumour target therapy was adapted to five different serum-free media (SFM) and to a protein-free medium (PFM). Only the PFM did not require a gradual adaptation to cell growth in the absence of serum. All tested SFM required a gradual adaptation (up to 35 days). For the majority of the SFM tested, cell specific productivity was not affected by the decrease in serum concentration during adaptation; however, cell growth was significantly affected by the serum decrease. Both cell growth and productivity were increased when PFM SMIF6 was used instead of the control medium. Long term measurements (approximately 100 days) of cell specific productivity for PFM and the two best SFM showed that productivity was maintained. This indicates the media capability to be used in long term production processes.

ENGINEERING FOR STERILITY AND CONTAINMENT: DESIGN OF A 225L “POLYMODAL” FERMENTER FOR THE CONTAINMENT OF P3 PATHOGENS

ABSTRACT The design approaches to the maintenance of sterility and containment in large scale fermentation plants desccribed together with the solutions arrived at in the design and fabrication of a multi-purpose 225 dm3 fermentation pilot plant capable of being used for the growth of animal cells or bacteria under P3 containment conditions as defined by the UK government Advisory Commiittee on Dangerous Pathogens.