Author
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Swayne, David |
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Submitted to: Developments in Biologicals
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/30/2004 Publication Date: 12/15/2004 Citation: Swayne, D.E. 2004. Application of new vaccine technologies for the control of transboundary diseses. Developments in Biologicals. 119:219-228. Interpretive Summary: Not required. Technical Abstract: Vaccines have played an important role in control of diseases of livestock and poultry including Transboundary Diseases. In the future, vaccines will play a greater role in controlling these diseases. Historically, inactivated whole viruses in various adjuvant systems have been used and will continue usage in the near future. For the future, emerging technologies will allow targeted use of only the protective antigens of the pathogen and will provide the opportunity to differentiation vaccinated from field-exposed animals. Furthermore, expression of cytokines by vaccines will afford earlier or greater enhancement of protection than can be achieved by the protective response elicited by the antigenic epitopes of the pathogen alone. Avian influenza (AI) is a good case study on future trends in vaccine design and usage. Inactivated AI virus (AIV) vaccines will continue as the primary vaccines used over the next 10 years. These vaccines will utilize homologous hemagglutinin subtypes either from usage of field strains or generation of new strains through use of infectious clones produced in the laboratory. The latter will allow creation of high growth reassortants, which will provide consistent high yields of antigen and result in potent vaccines. New viral and bacterial vectors with inserts of AIV hemagglutinin gene will be developed and potentially used in the field. Such new vectors will include herpesvirus-turkey, infectious laryngotracheitis virus, adenoviruses, various types of paramyxoviruses and Salmonella sp. In addition, there is a theoretical possibility of gene-deleted mutants that would allow use of live AIV vaccines, but application of such vaccines have inherent dangers for gene reassortment with field viruses for generation of disease causing strains. Subunit hemagglutinin protein and DNA hemagglutinin gene vaccines are possible, but with current technologies, the cost is prohibitive. In the future, effective 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 virus or bacterial vector systems will provide economic incentives for adoption over current labor-intensive manual individual bird injection methods used with today's AI vaccines. |
