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Current vaccines targeting surface proteins can drive antigenic variation resulting either in the emergence of more highly pathogenic viruses or of antigenically distinct viruses that escape control by vaccination and thereby persist in the host population. Influenza vaccines typically target the highly mutable surface proteins and do not provide protection against heterologous challenge. Vaccines which induce immune responses against conserved influenza epitopes may confer protection against heterologous challenge. We report here the results of vaccination with recombinant modified Vaccinia virus Ankara (MVA) and Adenovirus (Ad) expressing a fusion construct of nucleoprotein and matrix protein (NP+M1). Prime and boost vaccination regimes were trialled in different ages of chicken and were found to be safe and immunogenic. Interferon-γ (IFN-γ) ELISpot was used to assess the cellular immune response post secondary vaccination. In ovo Ad prime followed by a 4 week post hatch MVA boost was identified as the most immunogenic regime in one outbred and two inbred lines of chicken. Following vaccination, one inbred line (C15I) was challenged with low pathogenic avian influenza (LPAI) H7N7 (A/Turkey/England/1977). Birds receiving a primary vaccination with Ad-NP+M1 and a secondary vaccination with MVA-NP+M1 exhibited reduced cloacal shedding as measured by plaque assay at 7 days post infection compared with birds vaccinated with recombinant viruses containing irrelevant antigen. This preliminary indication of efficacy demonstrates proof of concept in birds; induction of T cell responses in chickens by viral vectors containing internal influenza antigens may be a productive strategy for the development of vaccines to induce heterologous protection against influenza in poultry.

Original publication

DOI

10.1016/j.vaccine.2012.11.047

Type

Journal article

Journal

Vaccine

Publication Date

11/01/2013

Volume

31

Pages

670 - 675

Keywords

Adenoviridae, Animals, Chickens, Genetic Vectors, Immunization, Secondary, Influenza A Virus, H7N7 Subtype, Influenza Vaccines, Influenza in Birds, Interferon-gamma, Poultry, RNA-Binding Proteins, Recombinant Proteins, T-Lymphocytes, Vaccination, Vaccinia virus, Viral Core Proteins, Viral Matrix Proteins, Virus Shedding