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Browsing by Author "Quackenbush, Sandra, advisor"

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    Japanese encephalitis virus: pathogenesis and immunity
    (Colorado State University. Libraries, 2010) Bosco-Lauth, Angela M., author; Bowen, Richard, advisor; Quackenbush, Sandra, advisor
    Japanese encephalitis virus (JEV) is a vector-borne disease of Asian origin that has the potential to spread into temperate regions across the globe. The recent incursion of the virus into Northern Australia illustrates its ability to replicate in different vectors and has led to an increase in the need for disease surveillance in the U.S. and other locations. The focus of this dissertation was to investigate the potential of some common North American mosquitoes to transmit JEV and to study the pathogenesis and immunity in animal models, namely horses and hamsters.
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    Molecular determinants of vector specificity in Highlands J virus
    (Colorado State University. Libraries, 2014) Borland, Erin M., author; Quackenbush, Sandra, advisor; Powers, Ann, advisor; Chen, Chaoping, committee member
    Highlands J Virus (HJV) is an understudied alphavirus that is closely related to western equine encephalitis virus (WEEV) and eastern equine encephalitis virus (EEEV). HJV is not known to cause disease in humans or equids, but it is a known avian pathogen with potential to significantly disrupt commercial production flocks. These studies compared the sequences of multiple strains of HJV in order to better characterize and compare the range of available strains. Strain B230, the prototype strain, was used to compare all other strains tested. Strain 64A-1519 was most similar to B230 with 22 nucleotide substitutions, only 5 of which resulted in a change in amino acid residues. Strain WX3-2AP was the most divergent with 167 nucleotide changes resulting in 8 amino acid residue changes. Four distinct lineages were identified through phylogenetic analysis. Lineage 1 consisted of strains B230 and 64A-15191. Lineage 2 consisted of strains AB-80-9, RU-M-80-259, and 73V-2540. Lineage 3 consisted of strains W17791 and two GenBank strains (744-01 and 585-01). Strain WX3-2AP was the sole member of Lineage 4. Vector capacity studies for HJV in live Culex tarsalis mosquitoes have not been published prior to these experiments. Cx. tarsalis mosquitoes were orally infected with one of four strains of HJV: B230, 64A-1519, WX3-2AP, or AB-80-9. The heads and bodies of mosquitoes were separated and processed independently to assess viral presence by cytopathic effects (CPE). The experiments were run in duplicate and at different times to ensure accuracy of results. Two infection patterns emerged: Lineage 1 strains had low infection and dissemination rates at all three time points, while Lineage 2 and 4 strains had high infection and dissemination rates which were more similar to those previously published for WEEV Imperial strain in Cx. tarsalis. Virus titrations were performed on mosquito heads and bodies, and Lineage 4 strain WX3-2AP was found to have the highest average titers. Mosquito bodies had the highest average titer on day 8 post infection and average titers for bodies ranged from 6.60 to 7.26 log10 pfu equivalents/body. Heads had no discernable pattern among titers or strains, but titers ranged between 6.01 and 6.80 log10 pfu equivalents/head. Saliva was collected from mosquitoes infected with Lineage 2 strain AB-80-9 to assess the potential presence of a salivary gland barrier resulting in lack of transmission. Twenty-two of 49 mosquitoes tested transmitted detectible levels of virus, meaning 44.9% of orally infected mosquitoes were able to actively transmit the virus. While the titer of the saliva on a per mL basis was impossible to compute since the volume of saliva could not be quantified, the titers of the samples collected ranged between 1.68 and 5.81 log10 pfu equivalents/saliva sample. By combining the data obtained by sequencing the strains with the data from the mosquito infections, a single amino acid difference between the attenuated Lineage 1 strains and the more virulent Lineage 2 and 4 strains was identified as being potentially responsible for the differences in infectivity. The mutation was located at genome nucleotide position 8605, E2 glycoprotein amino acid 69. This change caused the non-polar glycine in the attenuated Lineage 1 strains to be replaced with an acidic glutamic acid in the more virulent Lineage 2 and 4 strains. Additional studies are needed to assess the in vivo effects of this amino acid change in Cx. tarsalis mosquitoes.
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    Walleye dermal sarcoma virus Orf C: a potential oncolytic therapy
    (Colorado State University. Libraries, 2011) Magden, Elizabeth, author; Quackenbush, Sandra, advisor; VandeWoude, Sue, committee member; Biller, Barbara, committee member
    The taxonomy and nomenclature of the North American weevil genus Thecesternus Say was reviewed. Five previously described species are recognized as valid: affinis, foveolatus, hirsutus, humeralis, and maculosus. One new species, tumulosus, from Texas is described as new. The following new synonymy is proposed: longior LeConte 1856 (= affinis LeConte 1856) and albidus Pierce 1909 (= maculosus Pierce 1909). A neotype is designated for T. humeralis (Say). A key to identify the species is provided, with various illustrations of key morphological features characterizing these species. Additionally, distribution maps, species descriptions, and species differentiation for each species is provided. A cladistic hypothesis of the included species is presented. Walleye dermal sarcoma virus (WDSV) is a complex retrovirus that causes the growth of multifocal, cutaneous tumors in walleye fish (Sander vitreus vitreus). These virus-induced tumors spontaneously regress on a seasonal basis. The WDSV genome encodes three accessory proteins (rv-cyclin, Orf B, and Orf C) that are necessary for regulation of virus expression, tumor formation, and tumor regression. While rv-cyclin and B are critical for tumor development, Orf C contributes to the observed seasonal tumor regression. Previous studies have shown that Orf C targets the cell mitochondria and induces apoptosis. These studies suggest that Orf C-induced apoptosis leads to the observed tumor regression in fish infected with WDSV. To further define the mechanism(s) of apoptosis, we generated a recombinant lentivirus (Lenti Orf C) that expresses WDSV Orf C. By infecting cells with Lenti Orf C, we showed decreasing cell viability in association with increasing virus concentrations. We also demonstrated Orf C expression in mitochondrial, cytosolic, and nuclear cell fractions, with the strongest Orf C expression in cell nuclei. In addition, we identified two pro-apoptotic proteins that associate with Orf C, ANT and Bax, and identified a third protein, AIF, as a potential Orf C target. While significant progress has been made in elucidating the mechanism(s) of Orf C-induced apoptosis, further studies are necessary to determine which cellular proteins are the primary targets of Orf C. These apoptosis-inducing Orf C targets may be useful in developing future oncolytic therapies.