Objetivo
The programme aims to assess the environmental impact (if any) of the use of live recombinant virus vaccines. The host and tissue tropism of the recombinant vaccines will be determined and compared to those of the parent viruses. Possible evolution of an altered vaccine, following recombination of the recombinant vaccine and wild type viruses present in the environment, will be assessed.
Initial project objectives include:
construction of the different recombinant viruses based on capripox, Aujeszky's disease, and fowl pox virus;
construction of vectors to assess recombination between fowl pox virus and vaccinia virus;
recombination in vivo of wild type adenovirus (ADV) and modified ADV and of cowpox and vaccinia virus;
sera and tissue collection and screening for ecological surveys;
pathogenesis of cowpox in mammals.
Work to date has resulted in the construction of most of the recombinant viruses and construction of the vectors.
The virulence of the worst case recombinant virus NIA-3 gX E1 was compared with that of the virulent parent virus NIA-3 gX. 5 of the 3 week old specific pathogen free (SPF) piglets were infected intra-nasally with 10{5} pfu of the parent virus NIA-3 gX. and the recombinant virus NIA-3 gX E1. Preliminary findings indicate that both of the viruses cause sever and typical Aujeszky's disease and death. Three out of five died after inoculation with the recombinant and five out of five died after inoculation with the parent virus. Thus it appears that the worst case recombinant virus will not result in increased virulence of the virus in the field.
Sera samples have been collected from wild mammals for analysis for the presence of orthopoxvirus antibodies. Sera samples have also been collected from domestic animals in Continental Europe. These will be tested for the presence of antibodies to capripox or capripox related viruses. Samples from human and domestic animals with suspected cowpox have been screened. A further 14 strains of cowpox virus have been isolated, thus identifying geographical regions in which wild rodents will be sampled in an attempt to identify the reservoir host of the virus.
The project is continuing.
The development of recombinant vaccines has made rapid progress in the last few years. Environmental aspects related to the use of such vaccines are unknown and the safety regulations for the use of such vaccines are largely undefined. This collaborative programme aims to address the following aspects.
To provide a scientific basis to be able to predict and evaluate potential environmental problems involved in the use of these vaccines by identifying the factors that are pertinent to the safety of the vaccines, and developing the techniques necessary to evaluate the effect of the use of these vaccines prior to release.
Identification of factors that must be considered to develop the techniques necessary to evaluate the effect of the use of these vaccines prior to release.
To provide a basis for the establishment European and international legislation for the use of the recombinant vaccines. Studies will concentrate on possible changes in tissue and host tropism of the vector system as a result of the expression of the heterologous genes, and any associated pathogenic alterations. In addition we will study the possibility of recombination between live recombinant vaccine virus and wild type field virus. The virus vector systems to be studied, capripoxvirus, fowlpoxvirus, orthopoxvirus and herpes virus are expected to be applied in the field in the near future as multivalent recombinant vaccines.
Ámbito científico
Tema(s)
Data not availableConvocatoria de propuestas
Data not availableRégimen de financiación
CSC - Cost-sharing contractsCoordinador
GU24 0NF WOKING
Reino Unido