Animal & Avian Sciences Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2741
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Item Molecular markers of interspecies transmission of H2N2 and H9N2 avian influenza A viruses(2008-11-19) Sorrell, Erin Maureen; Perez, Daniel R; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Most avian influenza viruses do not replicate or transmit efficiently in mammals. The events that lead to interspecies transmission and host adaptation are unknown. Part one of this project set out to establish quail as an intermediate host of influenza. Our results indicate that adapting a mallard H2N2 virus in quail leads to expanded host range in chickens. The molecular changes, which occur during the adaptation in quail, are crucial for viral replication and transmission in chickens. Further adaptation of this quail-adapted virus in chickens leads to a 27 amino acid-deletion in the stalk region of the NA, changing the tissue tropism and temperature phenotype of the virus. H9N2 influenza viruses have created in poultry an endemic situation in much of Asia, Europe and the Middle East. This subtype, albeit low pathogenic, carries with it human receptor specificity and the ability to infect humans without prior adaptation. The generation of an influenza pandemic requires interspecies transmission of a novel strain, which can adapt to its new host through either reassortment or point mutations. Given that two previous pandemics were the result of reassortment between low pathogenic avian viruses and human subtypes of that period, and given the endemic situation of avian H9N2 viruses in Eurasia, for part two of this project, we wanted to determine if adaptation of an avian-human H9N2 reassortant in ferrets could support mammalian respiratory droplet transmission. Here we show for the first time that a reassortant virus carrying the HA and NA of an avian H9N2 virus can transmit in respiratory droplets. This is the first report of respiratory droplet transmission of H9N2 influenza, which carries profound implications for pandemic preparedness. The amino acid changes on the HA might identify critical, adaptive mutations necessary for respiratory transmission in subsequent pandemic avian influenza strains. Using reverse genetics we identified key combinations of this adapted reassortant that support respiratory droplet transmission.Item Adaptation of A/Mallard/Potsdam/178-4/83 (H2N2) in Japanese quail leads to Replication and Transmission in Chickens(2005-05-02) Sorrell, Erin Maureen; Perez, Daniel R; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Influenza is a single stranded, negative-sense RNA virus with a segmented genome that can infect avian and mammalian species. Influenza viruses from the avian reservoir do not seem to replicate efficiently in humans upon direct transmission. Therefore, an intermediate host is involved in generating mutations to create a more transmissible or an avian-human reassortant virus. Quail have been highlighted as a potential reservoir and intermediate host of avian influenza. To assess the potential of quail as an intermediate host, A/Mallard/Postdam/178-4/83, H2N2 was tested to determine if through adaptation in quail a mallard strain can replicate and transmit in quail, as well as other avian species. After six serial passages of lung homogenate a virus arose, which replicated and transmitted directly to contact quail. When chickens were infected with this quail-adapted virus replication and transmission were observed, while no replication was noted in the chickens infected with wild type H2N2 virus.