ObjectiveTo further develop fowl adenovirus-based vectors and determine their potential to generate replication-competent recombinant vaccines.
BackgroundDr. Nagy and her team is exploiting the molecular machinery of fowl adenovirus (FAdV; a strain that does not cause disease in poultry), to develop a system that can deliver specific antigens to the bird. The researchers identified portions of the FAdV genome that are not necessary to produce intact virus and, using modern techniques of molecular biology, replaced some of these sequences with genes coding for specific antigens. The resulting virus vector retains its ability to infect cells, but its genetic payload now also instructs host cells to produce the antigens that will elicit the desired immune response. Towards an avian influenza virus (AIV) vaccine, for example, this system can be used to deliver genes coding for hemagglutinin (HA), neuraminidase (NA), and other viral proteins. The power of this system lies in its flexibility. Using the same biological platform, a wide array of antigens can be produced. These vaccines can also be engineered to allow distinction between birds that were vaccinated and those that were naturally infected by intact virus. This capability, formally known as ”Differentiation of naturally Infected from Vaccinated Animals (DIVA)”, will be an important component of many commercially viable vaccination strategies in the future.
OutcomesDr. Nagy’s group has developed a number of FAdV-based vectors carrying various antigens specific to AIV and other viruses. Preliminary studies have shown that fowl adenovirus can be successfully administered in ovo at 18 days of incubation and that the resulting chicks develop good antibody (Ab) and innate immune responses. The researchers have also shown that orally administered virus induces good Ab response in chickens, and is not shed in the feces. Innate immune response to the vector virus has been characterized. Work is underway to develop an ELISA-based DIVA protocol to test serum from vaccinated chickens.
ApplicationThis research is part of an overall program to better understand the biology of avian influenza with the long-term goal of developing rational control strategies in domestic poultry. Dr. Nagy’s FAdV vector may serve as a platform for a new generation of AIV vaccines.
PublicationsCorredor JC, Nagy, É 2011. Antibody response and virus shedding of chickens inoculated with left end deleted fowl adenovirus 9-based recombinant viruses. Avian Diseases, 55(3):443-446.
*This research was part of the 2010-2013 Poultry Science Cluster which was supported by AAFC as part of Growing Forward, a federal-provincial-territorial initiative.