Submitted to: Veterinary Microbiology
Publication Type: Review Article
Publication Acceptance Date: 11/24/2016
Publication Date: 11/26/2017
Citation: Suarez, D.L., Pantin Jackwood, M.J. 2017. Recombinant viral-vectored vaccines for the control of avian influenza in poultry. Veterinary Microbiology. 206:144-151. doi:10.1016/j.vetmic.2016.11.025.
Interpretive Summary: Avian influenza virus is naturally found in wild waterfowl where it rarely causes clinical disease. However the viru often transmits to poultry, and in poultry it can cause a wide range of clinical disease from mild to severe with high mortality in poultry. The virus is often classified as to either low pathogenic or highly pathogenic depending on how severe the disease is in chickens. Because of the importance of the disease, vaccination is a commonly used tool for the control of both low pathogenic and highly pathogenic avian influenza viruses. Traditionally a low pathogenic virus isolated from poultry would be grown in the laboratory, inactivated and used as a vaccine. Although this type of vaccine can be effective, there are certain limitations on how this type of vaccine can be used. With modern vaccine technology we can now modify one virus to make the protein for another virus, allowing us to use one vaccine that can protect for two different viruses. Several of these viral vectored vaccines are now licensed for use for the control of avian influenza. This review looks at the different commercially available products and evaluates the pros and cons of each vaccine for the control of avian influenza in poultry.
Technical Abstract: Vaccination is a commonly used tool for the control of both low pathogenic and highly pathogenic avian influenza viruses. Traditionally inactivated adjuvanted vaccines made from a low pathogenic field strain has been used for vaccination, but advances in molecular biology has allowed a number of different viral vectored vaccines that express the hemagglutinin gene for avian influenza to be developed and licensed for use with avian influenza. As a group these vaccines can stimulate both a cellular and humoral immune response and when antigenically well matched to the target strain are effective at preventing clinical disease and reducing virus shedding if vaccinated birds do become infected. The vaccines can often be given to one day old chicks in the hatchery, which can provide early protection and a cost effective route of administration of the vaccine. All the vaccines, because they only express the HA gene can potentially be used to differentiate vaccinated and vaccinated and infected birds, which is often referred to as a DIVA strategy. Although a potential valuable tool for the surveillance of the virus in countries that vaccinate, this principal has currently not been applied. Concern remains that maternal antibody or pre-existing immunity to the vector to the influenza hemagglutinin insert can suppress the immune response. The viral vectored vaccines appear to work well with a prime boost strategy where the vectored vaccine is given first and a different type of vaccine, often a killed adjuvanted vaccine is given two or three weeks later.