The project aim is the further development of safe, improved poxvirus vectors for the expression of foreign antigens, for vaccination of animals and Man. The vectors have the advantage that they will be safer than earlier vaccine vectors, in that they can be used as nonreplicating poxviral vectors (NRPVs). Objectives of the project are:
(i) the development of cell lines permissive for the replication of new, non-replicating defective vaccinia vectors.
This will be achieved by transient and then permanent expression of vaccinia virus genes, which are essential to virus replication, in cell lines. These cell lines will then be used to allow isolation of viruses in which the complemented virus function is deleted;
(ii) the development of new high level promoters to optimise expression of foreign genes by non-replicating poxvirus vectors and to reduce the risk of recombination (thus increasing vector stability).
These will include natural poxvirus promoters in heterologous backgrounds as well as strong synthetic and chimaeric promoters;
(iii) the development of fusion proteins for antigen display. Epitopes will be fused to the haemagglutinin molecule of vaccinia virus and to the 39K immunodominant protein of fowlpox virus (FPV);
(iv) the development of poxviruses targeted to specific tissues.
(v) the development of new selection methods (GUS & GFP) for the isolation of poxvirus recombinants;
(vi) the identification of non-essential regions, in a host rangedefective vaccinia virus (MVA) and orf virus, suitable for the insertion of foreign genes These developments will be applied to:
(a) the artificial nonreplicating defective vaccinia virus,
(c) naturally host range-restricted FPV and
(d) attenuated orf virus, which is nonreplicating in some mammals (eg. cats an The relative efficacy of these recombinant vectors, incorporating the new developments as appropriate, will then be compared. This will be achieved by polyvalent expression of equivalent gene/promoter cassettes in the various vectors. Genes from human papilloma virus 16 (HPV-16) and from measles virus will be expressed in all the vectors (genes from canine distemper virus will be expressed initially only in orf virus).
Relative levels of foreign antigen expression by the recombinant viruses will be analysed in permissive and non-permissive cell types in vitro. The viruses will then be used in animal immunization studies, to monitor humoral and cellular responses to the foreign antigens.
Challenge/protection studies will also be performed using animal models for HPV-16, measles and canine distemper virus.
Funding SchemeCSC - Cost-sharing contracts