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To assess the pathogenicity and infectivity of influenza vaccine reassortants and their respective parental wild type viruses for chickens. This includes: 1) determining in vivo pathotype of wild type and reassortant vaccine candidate strains in chickens, and 2) assess in vivo infectivity and pathogenicity in chickens using simulated natural route of exposure (intranasal).
APPROACH: The challenge studies will be conducted in BSL-3 Enhanced facilities. Four vaccine candidates will be tested per year using the below study design: 1) conducting in vivo pathotype of virus strains by intravenous testing in chickens using intravenous pathogenicity index, and 2) conducting in vivo infectivity and pathogenicity testing by intranasal inoculation of chickens and determining the ability for the virus to grow as evident by virus shedding for oropharynx and cloaca, and ability to cause disease by assessing clinical features, serological reaction and histopathological changes to various organs.