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Submitted to: International Symposium on Avian Influenza
Publication Type: Abstract Only Publication Acceptance Date: 4/1/2015 Publication Date: 4/12/2015 Citation: Suarez, D.L. 2015. Recombinant viral vectored vaccines for the control of avian influenza: a review [abstract]. 9th International Symposium on Avian Influenza. p. 22. Interpretive Summary: Technical Abstract: The poultry industry has been at the forefront of developing recombinant viral vectored vaccines in an attempt to improve the immune response to vaccination. With AIV, the hemagglutinin surface glycoprotein is the key antigen for protection against infection. This allows a single gene to be transferred to viral vectors that allows protection for both viruses. A key advantage for the viral vectored viruses is the vaccines are administered as live viruses that provide both cellular and humoral immunity, and allows greater flexibility in administration of the vaccine. The safety profile of recombinant vaccines are generally superior to traditional live attenuated vaccines. Two of the more commonly used vaccines, the fowlpox recombinant and the herpes virus of turkey vaccines are designed to be administered at a day of age in the hatchery, which is a timely and cost effective approach for vaccination. Newcastle disease virus is also available in several countries, and can be used by spray or water administration. The vaccines also suffer from issues of maternal immunity to the avian influenza part of the vaccine. Although the viral vectored vaccines have been shown to be good potential tools for the control of AIV, several factors have limited their effectiveness. The commercially available vectored vaccines are available with only a single hemagglutinin gene of one subtype, H5, severely limiting how widely the vaccines can be used. Although the insert in the viral vector can be quickly changed, regulatory rules require these updated vaccines be licensed as “new” vaccines, which greatly adds to the cost of development. In addition, because these are genetically modified organisms, additional restrictions are imposed that make this class of vaccine unavailable in some countries. Regulatory changes that allow for streamlined approval processes are needed to fully benefit from this class of vaccines. |
