Author
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Swayne, David |
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Submitted to: Developments in Biologicals
Publication Type: Abstract Only Publication Acceptance Date: 2/26/2004 Publication Date: 4/13/2004 Citation: Swayne, D.E. 2004. New Vaccine Technologies For Transboundary Diseases. Developments In Biologicals. International Conference on the Control of Infectious Animal DIseases by Vaccinations, p.32, 2004. Interpretive Summary: Technical Abstract: Vaccines have played an important role in control of transboundary diseases of livestock and poultry. In the future, vaccines will play a greater role in controlling these diseases. Historically, inactivated whole viruses using various adjuvant systems have been used. Emerging technologies will allow targeted use of only the protective epitopes from specific proteins and will provide the opportunity to differentiation vaccinated from field-exposed animals. Furthermore, expression of cytokines by vaccines, will afford earlier protection than can be achieved by the active immune response alone. Avian influenza (AI) is a good case study on future trends in vaccine design and usage. Inactivated AI virus vaccines will continue as the primary vaccines used over the next 10 years. These vaccines will utilize homologous subtypes of hemagglutinin proteins as the primary protective antigen either from usage of field strains or generation of new strains through the reverse genetic process. The latter will allow creation of high growth reassortants, which will provide most consistent production of high yield antigen mass and result in potent vaccines. Virus vectors with inserts of homologous hemagglutinin gene will see increased usage. The licensed fowlpox-vectered-H5-AIV recombinant will receive more usage in the future and additional H5, H7 and H9 products will be developed. Furthermore, additional virus vectored products will be developed and tested with AIV-H5 gene inserts. This new virus vectored products could include herpesvirus-turkey, infectious laryngotracheitis virus, adenovirus and Newcastle disease virus vectors. In addition, there is a possibility of gene-deleted mutants to allow use of live AI virus vaccines, but application of a live AI vaccine has potential for gene reassortment with field viruses and production of disease, which will make regulators cautious for approval. Subunit hemagglutinin protein and DNA hemagglutinin gene vaccines are possible, but with current technologies, the cost is prohibitive. These future AI vaccines must prevent clinical signs and death, increase resistance of the host to infection, decrease the rate of replication and shedding of a challenge or field virus and provide uniform protection following single immunization. Mass application technologies of new vector systems will provide economic incentives for adoption over current labor intensive manual individual bird injection methods used with today's AI vaccines. |
