http://hdl.handle.net/1903/2231 2013-06-20T06:16:05Z http://hdl.handle.net/1903/13577 Title: Review of the Molecular Biology and Epidemiology of Infectious Laryngotracheitis (Gallid Herpesvirus-1) Authors: Menendez, Kimberly Rae Abstract: A review of the molecular biology and epidemiology of avian infectious laryngotracheitis (ILT) is conducted due to the outdated state of current ILT review material. The objective of this review is to include updated information on the molecular biology of Gallid herpesvirus 1 (GaHV-1), the causative agent of ILT, and to present the latest information on the molecular epidemiology of ILT. Recent developments in molecular biology specific to GaHV-1 have been made and are highlighted in this review, and the role of current and historical use of live-attenuated vaccines is associated with the global and molecular epidemiology of ILT. Also, target genes for detection and strain differentiation are compiled by region of the world, and the global distribution of ILT is illustrated. Additionally, the field of epigenetics related to virus-host interactions is reviewed, and the molecular, epidemiologic, and epigenetic factors investigated are related to prospects for future eradication of ILT. 2012-01-01T00:00:00Z http://hdl.handle.net/1903/13504 Title: ROLE OF FUSION PROTEIN IN NEWCASTLE DISEASE VIRUS PATHOGENESIS Authors: Samal, Sweety Abstract: The fusion (F) protein of Newcastle disease virus (NDV) is a type I membrane glycoprotein that mediates the merger of the viral envelope to the host cell membrane. The F protein activation initiates a series of conformational changes in the F protein leading to membrane merge which occurs at the cell surface at neutral pH thus modulating NDV entry and spread. The present studies have given an insight to understand the role of F protein in NDV pathogenesis by using established reverse genetic techniques. The F gene of NDV has six glycosylation sites, two of which are present in heptad repeats that facilitate conformational changes during fusion process. To understand the importance of the glycosylation sites in NDV replication and virulence, each site was eliminated individually and in combination on a cDNA clone of NDV strain BC. Our results suggest that glycosylation of F protein plays a major role in virulence and some of the N-glycosylation sites are critical for fusogenicity of the F protein thus modulating NDV infectivity. The F protein is synthesized as an inactive precursor, F0, which is only fusogenic after cleavage into disulfide-linked F1 and F2 polypeptides by host cell proteases. The amino acid sequence surrounding the F protein cleavage site determines the virulence of NDV, since different host proteases that cleave the F protein of virulent strains are present in more tissues than those that cleave the F protein of non-virulent strains. The role of conserved glutamine residue in NDV F protein cleavage site in viral pathogenesis has been examined. This study has helped us to understand the requirement of F protein cleavage site conserved amino acids in proteolytic processing and viral infectivity. Further in this study, the role of F protein cytoplasmic domain and conserved cysteine residues in viral pathogenesis have been explored using reverse genetics. These regions have been suggested to play important roles in F protein conformation, stability and thus affecting the fusion process and viral infectivity. In summary, the purpose of this work is to determine the important domains and residues of the NDV F protein that facilitates fusion process and regulates viral pathogenesis and immunogenicity. An understanding of how NDV F protein fusion process are regulated may lead to the creation of more effective therapies and better vaccine against NDV and other paramyxoviruses in general. 2012-01-01T00:00:00Z http://hdl.handle.net/1903/13362 Title: Characterization of influenza virus sialic acid receptors in minor poultry species Authors: Kimble, Brian; Ramirez Nieto, Gloria; Perez, Daniel R Abstract: It is commonly accepted that avian influenza viruses (AIVs) bind to terminal a2,3 sialic acid (SA) residues whereas human influenza viruses bind to a2,6 SA residues. By a series of amino acid changes on the HA surface protein, AIVs can switch receptor specificity and recognize a2,6 SA positive cells, including human respiratory epithelial cells. Animal species, like pigs and Japanese quail, that contain both a2,3 and a2,6 SA become ideal environments for receptor switching. Here, we describe the SA patterns and distributions in 6 common minor domestic poultry species: Peking duck, Toulouse geese, Chinese ring-neck pheasant, white midget turkey, bobwhite quail, and pearl guinea fowl. Lectins specific to a2,3 and a2,6 SA (Maakia amurensis agglutinin and Sambuca nigra agglutinin, respectively) were used to detect SA by an alkaline phosphotase-based method and a fluorescent-based method. Differences in SA moieties and their ability to bind influenza viruses were visualized by fluorescent labeling of 4 different H3N2 influenza viruses known to be specific for one receptor or the other. The geese and ducks showed a2,3 SA throughout the respiratory tract and marginal a2,6 SA only in the colon. The four other avian species showed both a2,3 and a2,6 SA in the respiratory tract and the intestines. Furthermore, the turkey respiratory tract showed a positive correlation between age and a2,6 SA levels. The fact that these birds have both avian and human flu receptors, combined with their common presence in backyard farms and live bird markets worldwide, mark them as potential mixing bowl species and necessitates improved surveillance and additional research about the role of these birds in influenza host switching. 2010-12-09T00:00:00Z http://hdl.handle.net/1903/13360 Title: Improved hatchability and efficient protection after in ovo vaccination with live-attenuated H7N2 and H9N2 avian influenza viruses Authors: Cai, Yibin; Song, Haichen; Ye, Jianqiang; Shao, Hongxia; Padmanabhan, Rangarajan; Sutton, Troy C; Perez, Daniel R Abstract: Mass in ovo vaccination with live attenuated viruses is widely used in the poultry industry to protect against various infectious diseases. The worldwide outbreaks of low pathogenic and highly pathogenic avian influenza highlight the pressing need for the development of similar mass vaccination strategies against avian influenza viruses. We have previously shown that a genetically modified live attenuated avian influenza virus (LAIV) was amenable for in ovo vaccination and provided optimal protection against H5 HPAI viruses. However, in ovo vaccination against other subtypes resulted in poor hatchability and, therefore, seemed impractical. In this study, we modified the H7 and H9 hemagglutinin (HA) proteins by substituting the amino acids at the cleavage site for those found in the H6 HA subtype. We found that with this modification, a single dose in ovo vaccination of 18- day old eggs provided complete protection against homologous challenge with low pathogenic virus in ≥70% of chickens at 2 or 6 weeks post-hatching. Further, inoculation of 19-day old egg embryos with 10 6 EID50 of LAIVs improved hatchability to ≥90% (equivalent to unvaccinated controls) with similar levels of protection. Our findings indicate that the strategy of modifying the HA cleavage site combined with the LAIV backbone could be used for in ovo vaccination against avian influenza. Importantly, with protection conferred as early as 2 weeks post-hatching, with this strategy birds would be protected prior to or at the time of delivery to a farm or commercial operation. 2011-01-21T00:00:00Z