The injection of a DNA plasmid containing a gene encoding an antigen under the control of a eukaryotic promoter is a novel approach to vaccination which has received considerable attention in the past few years.
Immune responses have been induced with genes from a variety of infectious agents including influenza, HBV, HIV, rabies, LCMV, malaria and mycoplasma. Protection from disease has been reported. The USA has made significant progress in this field and a clinical trial of a DNA vaccine has already begun. There are several safety and regulatory concerns regarding this form of vaccination.
- The injected DNA may integrate into the host chromosome resulting in a transformation (or tumorigenic) event,
- Injected DNA may persist and be expressed for a considerable time within the recipient which could lead to the induction of immunopathological reactions, tolerance or antigenic competition,
- The inclusion of genes for regulatory cytokines, which may improve the immune response, may have serious consequences such as the stimulation of one arm of the immune response at the expense of the other leading to generalised immunosuppression or chronic inflammation.
To date, there is a paucity of scientific data in relation to the above issues regarding the safety of DNA vaccines. Two reports exist investigating whether integration of a DNA vaccine into the host chromosome occurs. The results were negative although the methods were not validated. There is a similar lack of information on potential immunopathological reactions. In order to ensure the safe application of DNA vaccines, the specific objectives of this project are:
- to validate methods for assessing integration of a DNA vaccine into the host chromosome,
- to apply such methods to the analysis of potential integration of a DNA vaccine,
- to analyze the persistence of expression of antigen and of DNA, - to investigate the immunological basis of DNA vaccination, such as the site of expression of the antigen and the nature of the B and T cell response, in order to increase our understanding of possible adverse immunological reactions,
- to investigate specific conditions likely to lead to immunopathological conditions.
The project will utilise nucleic acid vaccines containing the haemagglutinin and nucleoprotein genes of influenza virus and the fusion and glycoprotein genes of respiratory syncytial virus in mice, both viruses being likely candidates for future DNA vaccines. It is important for public confidence that safety studies are performed by independent scientists involved in the control of vaccines and that the data on safety does not derive entirely from industry. Within the EU, DNA vaccines will be regulated by the Committee for Proprietary Medicinal Products (CPMP). Two out the five partners in this consortium are members of the CPMP's Biotechnology Working Party. The data generated by this project will provide assurance of the safety of DNA vaccines, help formulate safety requirements, and will directly assist the CPMP and industry on the suitability of this novel form of vaccination. In order to give European vaccine industry swift and accurate information about developments we have established open links of communication with the European Vaccine Manufacturers (EVM).
Funding SchemeCSC - Cost-sharing contracts
RG20 7NN Newbury
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