- To delineate the cellular and molecular mechanisms of chicken immune responses to avian influenza virus.
- To utilize these responses to develop vaccines that effectively control replication and transmission of the virus.
BackgroundImmunology of avian influenza virus (AIV) infection in the chicken has not been extensively studied. While it has been established that both HA and NA antigens of AIV elicit neutralizing antibodies, the roles played by these antibodies in protecting the chicken from infection is not entirely clear. Similarly, it is known that T cells play a role in immunity to AIV, but there is little information on the mechanism by which they do so. A better understanding of the chicken’s immune response to AIV infection will lead to better strategies to control the virus.
OutcomesDr. Sharif’s research has provided valuable information on various aspects of chicken immune responses to AIV. His research team obtained evidence that T cells respond to the HA antigen of AIV and characterized immune responses to a commercial vaccine (not approved for use in Canada). The researchers then set their sights on developing a more effective, virosome-based vaccine. Virosomes are virus-like particles that are devoid of nucleic acids and hence cannot replicate. By virtue of their physicochemical characteristics, virosomes can gain access to the compartments inside host cells and induce antibody- and cell-mediated responses, both of which are necessary for protection against influenza. By contrast, inactivated (or killed) influenza vaccines are not able to produce this full spectrum of immune responses. Some of the antibodies induced by the virosomes were shown to be cross-reactive to a range of AIV subtypes, which further increases their potential utility as a vaccine. Work is ongoing to improve the immunogenicity of the virosomes. Results thus far demonstrate that virosomes combined with certain adjuvants can reduce AIV shedding and elicit virus-specific antibody responses in vaccinated birds.
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. Results thus far suggest the virosome vaccine system could be part of such a strategy.
Funding$388,632 ($166,132 AAFC*, $40,000 PIC, $87,500 OMAFRA (in-kind), $95,000 OMAFRA (cash))
PublicationsMallick AI, Parvizi P, Read LR, Nagy E, Behboudi S, Sharif S 2011. Enhancement of immunogenicity of a virosome-based avian influenza vaccine in chickens by incorporating CpG-ODN. Vaccine, 29:1657-1665. Mallick AI, Haq K, Brisbin JT, Mian MF, Kulkarni RR, Sharif S 2011. Bioactivity of a recombinant chicken interferon-gamma expressed using a baculovirus expression system. J Interferon Cytoine Res. 31(6):493-500. Mallick AI, Kulkarni RR, St Paul M, Parvizi P, Nagy E, Behboudi S, Sharif S. Vaccination with CpG-Adjuvanted Avian Influenza Virosomes Promotes Antiviral Immune Responses and Reduces Virus Shedding in Chickens. Viral Immunol. 2012 Apr.
*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.