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Title: Avian influenza mucosal vaccination in chickens with replication-defective recombinant adenovirus vaccine

item TORO, HAROLDO - Auburn University
item Suarez, David
item TANG, DE-CHU - Vaxin, Inc
item VAN GINKEL, FREDERIK - Auburn University
item BREEDLOVE, CASSANDRA - Auburn University

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2010
Publication Date: 2/1/2011
Citation: Toro, H., Suarez, D.L., Tang, D.C., Van Ginkel, F.W., Breedlove, C. 2011. Avian influenza mucosal vaccination in chickens with replication-defective recombinant adenovirus vaccine. Avian Diseases. 55:43-47.

Interpretive Summary: Avian influenza virus can cause mild to severe disease in many poultry species, and the control of the virus is important to mitigate its affect. One way to control the virus is through vaccination. A well vaccinated bird is unlikely to be infected when exposed to the virus, and if infected will not produce a large amount of virus that can infect other birds. However our current influenza vaccines must be given to the birds individually which requires a lot of manpower. Ideally a vaccination method that can be given in the drinking water or by a spray in the air, as is performed with other poultry viruses, would reduce administration costs and speed the vaccination procedure. A human adeno-virus that has been modified to be extremely safe was made that also expresses the influenza hemagglutinin gene. This vaccine was evaluated to see if it could be given by a mass administration route. This vaccine was previously shown to work given as an injection. The vaccine when tested in chickens only provided partial protection. The procedure may provide some advantages when administered with other types of vaccines, but it does not appear to be suitable as a single vaccine given by the spray route.

Technical Abstract: We evaluated protection conferred by mucosal vaccination with replication competent adenovirus (RCA)-free recombinant adenovirus expressing a codon-optimized avian influenza (AI) H5 gene (AdTW68.H5ck). Commercial layer-type chicken groups were singly vaccinated ocularly at 5 days of age, or singly vaccinated via spray at 5 days of age, or ocularly primed at 5 days and ocularly boosted at 15 days of age. Only chickens primed and boosted via the ocular route developed AI systemic antibodies with maximum haemagglutination inhibition (HI) mean titres of 3.9 log2 at 32 days of age. In contrast, single vaccination via the ocular or spray routes maintained an antibody status similar to unvaccinated controls. All chickens (16/16) subjected to ocular priming and boosting with AdTW68.H5ck survived challenge with highly pathogenic (HP) AI virus A/Chicken/Queretaro/14588-19/95 (H5N2). Single ocular vaccination resulted in 63% (10/16) of birds surviving the challenge followed by 44% (7/16) survival of single sprayed vaccinated birds. Birds vaccinated twice via the ocular route also showed significantly lower (P<0.05) AI virus RNA concentrations in oropharyngeal swabs compared to unvaccinated/challenged controls. Finally, we investigated interferon-gamma (IFN-gamma) and interleukin-6 (IL-6) expression in chickens vaccinated in ovo and boosted via the ocular route. Interestingly, in ovo immunization with AdTW68.H5ck induced immune cytokine responses in the Harderian gland irrespective of ocular boost with increased expression of IL-6 and IFN-gamma compared to unvaccinated controls.