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Bulletin No. 16 - Fall 2003
Sixth International Congress of Veterinary Virology - Saint-Malo (France)- No Category
AUDONNET JC
New advances in veterinary vaccines.
Proceedings of the 6th International Congress of Veterinary Virology, 2003, 42-45
The group of classical vaccines comprises live vaccines, inactivated vaccines and subunit vaccines, all of them are briefly reviewed. Novel-technology-based vaccines, which progressively substitute classical vaccines, utilize recombinant DNA or other novel technology. Modified or deleted vaccines allow to make a virus or a bacteria highly unlikely or unable to revert to virulence, and allow as well to differentiate vaccinated from infected animals. The technology of live vectored vaccines consists in inserting genes in a non-pathogenic carrier (virus or bacteria) so as to present a recombinant immunogen to the immune system, in a situation identical to infection and trigger immune responses. Poxviruses are already used as vaccine vectors, several examples are reviewed. Herpesvirus vectors are investigated as well, in particular for poultry vaccines. Adenovirus vectors are under development, the main example available is that of canine adenovirus type 2 (CAV2) as vector of canine distemper virus (CDV) HA and E proteins. This vaccine was shown to provide effective protection in seronegative dogs using intranasal route and in seropositive dogs using the subcutaneous route. Among potential live bacterial vectors, Salmonella represents a vector of choice for animal use but no conclusive results has been obtained yet. The technology of recombinant subunit vaccines consists in using bacteria (E.coli) to produce immunogenic factors. These type of vaccines is often associated to adjuvants in order to enhance immunogenicity. Another pathway is DNA vaccines, that is the insertion of genes (naked DNA) within transinfected cells and their subsequent expression by the cells. DNA vaccination represents a field with great prospects. Even if peptide-based vaccines could be another direction to explore, the underlying complexity of such a technology keeps them off of any commercial reality. Much work will be necessary in order to further develop and master novel technology based vaccines and fully introduce them on the market.
