Biology of fowl adenoviruses

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Avian health, including protection from infectious agents, is an important component of reliably providing much of the world's population a safe supply of this staple food source. Even though the infectious agents differ, birds are as susceptible to infectious diseases as humans are. This has been dramatically illustrated in the latest outbreak of the avian H5N1 influenza virus in South East Asia and Europe. Similarly in 2004 in western Canada there was an outbreak caused by influenza strain, H7N3 whereby many birds died and many more were destroyed. Not only do such diseases impact on the chicken industry directly, but they also affect the reliability of this food supply. In my research I study several avian viral diseases with the aim of being able to better understand them, provide diagnostic tools for detecting them and developing vaccines or antiviral strategies to better protect birds from these diseases. In the current proposal and in my more recent research I have focussed on a group of viruses called fowl adenoviruses (FAdVs) which infect mainly chickens. While some infections with FAdVs appear to be asymptomatic, other FAdVs are highly virulent with high death rates and some FAdVs seem to compromise the ability of the immune system to counteract infection with other microbial agents. My research has already uncovered major differences in the genetic composition of avian versus mammalian adenoviruses and I believe these differences in avian adenoviruses relate directly to their specific interaction with the avian host and some are responsible for the biological effects different FAdVs have on the infected birds. In order to determine which genes are responsible for various aspects of virus replication and pathology in the host, I developed a simple (FAdmid) system in which I can either remove a complete gene or alter it. Using this method, I will generate a panel of FAdV mutants defective in various genes unique to FAdV and test the effect of these mutants on virus replication, first in cell culture to determine which genes are essential for virus replication, and then in chickens to monitor differences in pathogenesis and immune response between birds infected with the wild type (unchanged) virus vs the mutated ones.