Browsing by Author "Hall, Karen"

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    A Novel Pathogenic Mammalian Orthoreovirus from Diarrheic Pigs and Swine Blood Meal in the United States
    Narayanappa, Athmaram Thimmasandra; Sooryanarain, Harini; Deventhiran, Jagadeeswaran; Cao, Dianjun; Venkatachalam, Backiyalakshmi Ammayappan; Kambiranda, Devaiah; LeRoith, Tanya; Heffron, C. Lynn; Lindstrom, Nicole; Hall, Karen; Jobst, Peter; Sexton, Cary; Meng, Xiang-Jin; Elankumaran, Subbiah (American Society for Microbiology, 2015-05)
    Since May 2013, outbreaks of porcine epidemic diarrhea have devastated the U.S. swine industry, causing immense economic losses. Two different swine enteric coronaviruses (porcine epidemic diarrhea virus and Delta coronavirus) have been isolated from the affected swine population. The disease has been reported from at least 32 states of the United States and other countries, including Mexico, Peru, Dominican Republic, Canada, Columbia, Ecuador, and Ukraine, with repeated outbreaks in previously infected herds. Here we report the isolation and characterization of a novel mammalian orthoreovirus 3 (MRV3) from diarrheic feces of piglets from these outbreaks in three states and ring-dried swine blood meal from multiple sources. MRV3 could not be isolated from healthy or pigs that had recovered from epidemic diarrhea from four states. Several MRV3 isolates were obtained from chloroform-extracted pig feces or blood meal in cell cultures or developing chicken embryos. Biological characterization of two representative isolates revealed trypsin resistance and thermostability at 90 degrees C. NextGen sequencing of ultrapurified viruses indicated a strong homology of the S1 segment to mammalian and bat MRV3. Neonatal piglets experimentally infected with these viruses or a chloroform extract of swine blood meal developed severe diarrhea and acute gastroenteritis with 100% mortality within 3 days postinfection. Therefore, the novel porcine MRV3 may contribute to enteric disease along with other swine enteric viruses. The role of MRV3 in the current outbreaks of porcine epidemic diarrhea in the United States remains to be determined, but the pathogenic nature of the virus warrants further investigations on its epidemiology and prevalence. IMPORTANCE Porcine orthoreoviruses causing diarrhea have been reported in China and Korea but not in the United States. We have isolated and characterized two pathogenic reassortant MRV3 isolates from swine fecal samples from porcine epidemic diarrhea outbreaks and ring-dried swine blood meal in the United States. These fecal and blood meal isolates or a chloroform extract of blood meal induced severe diarrhea and mortality in experimentally infected neonatal pigs. Genetic and phylogenetic analyses of two MRV3 isolates revealed that they are identical but differed significantly from nonpathogenic mammalian orthoreoviruses circulating in the United States. The present study provides a platform for immediate development of suitable vaccines and diagnostics to prevent and control porcine orthoreovirus diarrhea.
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    Surface water flow resistance due to emergent wetland vegetation
    Hall, Karen (Virginia Tech, 2012-04-11)
    The key to a successful wetland design is duplicating the hydroperiod of the desired wetland type. Dense wetland vegetation affects surface water flow rates by increasing flow resistance. Prior research represented the vegetation as individual stems; however, many wetland species grow in clumps. Therefore, the objectives of this study were to investigate the effect of clumping vegetation on flow resistance and to develop a prediction equation for use in wetland design. A 6-m by 1-m by 0.4-m recirculating flume was planted with mature common rush, Juncus effusus, a common emergent wetland plant. Three different flow rates (3, 4, and 5 L/s) and three different tailgate heights (0, 2.5, and 5 cm) were used to simulate a variety of wetland conditions. Plant spacing and clump diameter were varied (20 and 25 cm, 8 and 12 cm, respectively). Friction factors ranged from 9 to 40 and decreased with increasing plant density. Non-dimensional parameters determined through Buckingham Pi analysis were used in a regression analysis to develop a prediction model. Results of the regression analysis showed that the fraction of vegetated occupied area (P) was most significant factor in determining friction factor.