34 results on '"Rochon K"'
Search Results
2. Equipping TFC Parents as Treatment Providers: Findings from Expert Interviews
- Author
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Rochon K. Steward, Bethany R. Lee, Suzanne E. U. Kerns, and Danielle R. Phillips
- Subjects
050103 clinical psychology ,Medical education ,business.industry ,media_common.quotation_subject ,Best practice ,education ,05 social sciences ,Peer support ,Experiential learning ,Coaching ,Group care ,Foster care ,Transformative learning ,Developmental and Educational Psychology ,0501 psychology and cognitive sciences ,Life-span and Life-course Studies ,Psychology ,business ,Welfare ,050104 developmental & child psychology ,media_common - Abstract
As U.S. policy and practice further constrains the prevalence of residential treatment for youth with emotional and behavior challenges, treatment foster care (TFC) placements are expected to expand and serve challenging youth who were previously receiving group care placement. Treatment foster parents play an essential role in the delivery of TFC and its potential to be a transformative and healing environment for youth. Using qualitative analysis of semi-structured interviews from 23 experts in TFC practice as well as more general child welfare training and implementation science, this paper seeks to build knowledge around the training and support needs of TFC parents from the perspectives of TFC experts. Findings suggest the importance of TFC parents viewing themselves as treatment providers and not just parents. They need to have competencies specific to working as a member of a treatment team, knowledge of public systems, and skills to manage youth challenging behaviors. Best practices in equipping TFC parents should follow adult learning principles that focus on experiential learning with peer support and ongoing coaching or reinforcement.
- Published
- 2020
3. Stable Fly (Diptera: Muscidae)—Biology, Management, and Research Needs
- Author
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Rochon, K, primary, Hogsette, J A, additional, Kaufman, P E, additional, Olafson, P U, additional, Swiger, S L, additional, and Taylor, D B, additional
- Published
- 2021
- Full Text
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4. Equipping TFC Parents as Treatment Providers: Findings from Expert Interviews
- Author
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Lee, Bethany R., primary, Phillips, Danielle R., additional, Steward, Rochon K., additional, and Kerns, Suzanne E. U., additional
- Published
- 2020
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5. Technical Assistance: A Comparison Between Providers and Recipients
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Leah Bartley, Berenice Rushovich, Charlotte Lyn Bright, and Rochon K. Steward
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Health (social science) ,Public Administration ,Sociology and Political Science ,business.industry ,Strategy and Management ,media_common.quotation_subject ,Public relations ,Focus group ,Nursing ,Political science ,Quality (business) ,business ,Welfare ,media_common - Abstract
This study aims to understand how the technical assistance (TA) provided by a child welfare implementation center was perceived by TA recipients and providers, with focus on similarities and differences in perceptions. Six focus groups were conducted with TA recipients (n = 35), and individual interviews were conducted with TA providers (n = 12). Results suggest a comprehensive framework was critical, a team approach was essential, the quality of relationships and communication between providers and recipients was important. The findings have implications for supporting readiness for change, ensuring leadership support, clarifying roles, and addressing organizational factors to enhance the success of the TA experience.
- Published
- 2015
6. Persistence and Retention of Porcine Reproductive and Respiratory Syndrome Virus in Stable Flies (Diptera: Muscidae)
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Rochon, K., primary, Baker, R. B., additional, Almond, G. W., additional, Gimeno, I. M., additional, Pérez de León, A. A., additional, and Watson, D. W., additional
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- 2015
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7. Technical Assistance: A Comparison Between Providers and Recipients
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Rushovich, Berenice R., primary, Bartley, Leah H., additional, Steward, Rochon K., additional, and Bright, Charlotte L., additional
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- 2015
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8. Dispersion and Sampling of Adult Dermacentor andersoni in Rangeland in Western North America
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Rochon, K., primary, Scoles, G. A., additional, and Lysyk, T. J., additional
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- 2012
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9. Assessment of Stomoxys calcitrans (Diptera: Muscidae) as a Vector of Porcine Reproductive and Respiratory Syndrome Virus
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Rochon, K., primary, Baker, R. B., additional, Almond, G. W., additional, and Watson, D. W., additional
- Published
- 2011
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10. Activity of Bacillus thuringiensis Isolates Against Immature Horn Fly and Stable Fly (Diptera: Muscidae)
- Author
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Lysyk, T. J., primary, Kalischuk-tymensen, L. D., additional, Rochon, K., additional, and Selinger, L. B., additional
- Published
- 2010
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11. Retention ofEscherichia coliby House Fly and Stable Fly (Diptera: Muscidae) During Pupal Metamorphosis and Eclosion
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Rochon, K., primary, Lysyk, T. J., additional, and Selinger, L. B., additional
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- 2005
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12. Retention of Escherichia coli by House Fly and Stable Fly (Diptera: Muscidae) During Pupal Metamorphosis and Eclosion
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Rochon, K., primary, Lysyk, T. J., additional, and Selinger, L. B., additional
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- 2005
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13. Persistence of Escherichia coli in Immature House Fly and Stable Fly (Diptera: Muscidae) in Relation to Larval Growth and Survival
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Rochon, K., primary, Lysyk, T. J., additional, and Selinger, L. B., additional
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- 2004
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14. Retention of Escherichia coli by house fly and stable fly (Diptera: Muscidae) during pupal metamorphosis and eclosion
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Rochon, K., Timothy Lysyk, and Selinger, L. B.
15. The Structure of the Drp1 Lattice on Membrane.
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Peng R, Rochon K, Stagg SM, and Mears JA
- Abstract
Mitochondrial health relies on the membrane fission mediated by dynamin-related protein 1 (Drp1). Previous structural studies of Drp1 on remodeled membranes were hampered by heterogeneity, leaving a critical gap in the understanding of the mitochondrial fission mechanism. Here we present a cryo-electron microscopy structure of full-length human Drp1 decorated on membrane tubules. Using the reconstruction of average subtracted tubular regions (RASTR) technique, we report that Drp1 forms a locally ordered lattice along the tubule without global helical symmetry. The filaments in the lattice are similar to dynamin rungs with conserved stalk interactions. Adjacent filaments are connected by GTPase domain interactions in a novel stacked conformation. Additionally, we observed contact between Drp1 and membrane that can be assigned to variable domain sequence. We identified two states of the Drp1 lattice representing conformational changes related to membrane curvature differences. Together these structures revealed a putative mechanism by which Drp1 constricts mitochondria membranes in a stepwise, "ratchet" manner.
- Published
- 2024
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16. Structural basis for regulated assembly of the mitochondrial fission GTPase Drp1.
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Rochon K, Bauer BL, Roethler NA, Buckley Y, Su CC, Huang W, Ramachandran R, Stoll MSK, Yu EW, Taylor DJ, and Mears JA
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- Animals, Microtubule-Associated Proteins metabolism, Dynamins metabolism, Mitochondria metabolism, Mitochondrial Proteins metabolism, Mammals metabolism, GTP Phosphohydrolases metabolism, Mitochondrial Dynamics
- Abstract
Mitochondrial fission is a critical cellular event to maintain organelle function. This multistep process is initiated by the enhanced recruitment and oligomerization of dynamin-related protein 1 (Drp1) at the surface of mitochondria. As such, Drp1 is essential for inducing mitochondrial division in mammalian cells, and homologous proteins are found in all eukaryotes. As a member of the dynamin superfamily of proteins (DSPs), controlled Drp1 self-assembly into large helical polymers stimulates its GTPase activity to promote membrane constriction. Still, little is known about the mechanisms that regulate correct spatial and temporal assembly of the fission machinery. Here we present a cryo-EM structure of a full-length Drp1 dimer in an auto-inhibited state. This dimer reveals two key conformational rearrangements that must be unlocked through intramolecular rearrangements to achieve the assembly-competent state observed in previous structures. This structural insight provides understanding into the mechanism for regulated self-assembly of the mitochondrial fission machinery., (© 2024. The Author(s).)
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- 2024
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17. Allosteric control of dynamin-related protein 1 through a disordered C-terminal Short Linear Motif.
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Pérez-Jover I, Rochon K, Hu D, Mahajan M, Madan Mohan P, Santos-Pérez I, Ormaetxea Gisasola J, Martinez Galvez JM, Agirre J, Qi X, Mears JA, Shnyrova AV, and Ramachandran R
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- Mitochondria metabolism, Hydrolysis, Membrane Fusion, Mitochondrial Dynamics, Mitochondrial Proteins metabolism, Dynamins metabolism, GTP Phosphohydrolases metabolism
- Abstract
The mechanochemical GTPase dynamin-related protein 1 (Drp1) catalyzes mitochondrial and peroxisomal fission, but the regulatory mechanisms remain ambiguous. Here we find that a conserved, intrinsically disordered, six-residue Short Linear Motif at the extreme Drp1 C-terminus, named CT-SLiM, constitutes a critical allosteric site that controls Drp1 structure and function in vitro and in vivo. Extension of the CT-SLiM by non-native residues, or its interaction with the protein partner GIPC-1, constrains Drp1 subunit conformational dynamics, alters self-assembly properties, and limits cooperative GTP hydrolysis, surprisingly leading to the fission of model membranes in vitro. In vivo, the involvement of the native CT-SLiM is critical for productive mitochondrial and peroxisomal fission, as both deletion and non-native extension of the CT-SLiM severely impair their progression. Thus, contrary to prevailing models, Drp1-catalyzed membrane fission relies on allosteric communication mediated by the CT-SLiM, deceleration of GTPase activity, and coupled changes in subunit architecture and assembly-disassembly dynamics., (© 2024. The Author(s).)
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- 2024
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18. Allosteric control of dynamin-related protein 1-catalyzed mitochondrial fission through a conserved disordered C-terminal Short Linear Motif.
- Author
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Pérez-Jover I, Rochon K, Hu D, Mohan PM, Santos-Perez I, Gisasola JO, Galvez JMM, Agirre J, Qi X, Mears JA, Shnyrova AV, and Ramachandran R
- Abstract
The mechanochemical GTPase dynamin-related protein 1 (Drp1) catalyzes mitochondrial fission, but the regulatory mechanisms remain ambiguous. Here we found that a conserved, intrinsically disordered, six-residue S hort Li near M otif at the extreme Drp1 C-terminus, named CT-SLiM, constitutes a critical allosteric site that controls Drp1 structure and function in vitro and in vivo . Extension of the CT-SLiM by non-native residues, or its interaction with the protein partner GIPC-1, constrains Drp1 subunit conformational dynamics, alters self-assembly properties, and limits cooperative GTP hydrolysis, leading to the fission of model membranes in vitro . In vivo , the availability of the native CT-SLiM is a requirement for productive mitochondrial fission, as both non-native extension and deletion of the CT-SLiM severely impair its progression. Thus, contrary to prevailing models, Drp1-catalyzed mitochondrial fission relies on allosteric communication mediated by the CT-SLiM, deceleration of GTPase activity, and coupled changes in subunit architecture and assembly-disassembly dynamics., Competing Interests: Additional Declarations: Competing interests: The authors declare no competing interests.
- Published
- 2023
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19. Disease-associated mutations in Drp1 have fundamentally different effects on the mitochondrial fission machinery.
- Author
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Bauer BL, Rochon K, Liu JC, Ramachandran R, and Mears JA
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- Dynamins genetics, Dynamins metabolism, GTP Phosphohydrolases genetics, GTP Phosphohydrolases metabolism, Mutation, Lipids, Mitochondrial Proteins genetics, Mitochondrial Proteins metabolism, Mitochondrial Dynamics genetics, Microtubule-Associated Proteins genetics, Microtubule-Associated Proteins metabolism
- Abstract
Patient mutations have been identified throughout dynamin-related protein 1 (Drp1), the key protein mediator of mitochondrial fission. These changes generally impact young children and often result in severe neurological defects and, in some instances, death. Until now, the underlying functional defect leading to patient phenotypes has been largely speculative. We therefore analyzed six disease-associated mutations throughout the GTPase and middle domains (MD) of Drp1. The MD plays a role in Drp1 oligomerization, and three mutations in this region were predictably impaired in self-assembly. However, another mutant in this region (F370C) retained oligomerization capability on pre-curved membranes despite being assembly-limited in solution. Instead, this mutation impaired membrane remodeling of liposomes, which highlights the importance of Drp1 in generating local membrane curvature before fission. Two GTPase domain mutations were also observed in different patients. The G32A mutation was impaired in GTP hydrolysis both in solution and in the presence of lipid but remains capable of self-assembly on these lipid templates. The G223V mutation also exhibited decreased GTPase activity and was able to assemble on pre-curved lipid templates; however, this change impaired membrane remodeling of unilamellar liposomes similar to F370C. This demonstrates that the Drp1 GTPase domain also contributes to self-assembly interactions that drive membrane curvature. Overall, the functional defects caused by mutations in Drp1 are highly variable even for mutations that reside within the same functional domain. This study provides a framework for characterizing additional Drp1 mutations to provide a comprehensive understanding of functional sites within this essential protein., (© The Author(s) 2023. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)
- Published
- 2023
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20. Adaptive exhaustion during prolonged intermittent hypoxia causes dysregulated skeletal muscle protein homeostasis.
- Author
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Attaway AH, Bellar A, Mishra S, Karthikeyan M, Sekar J, Welch N, Musich R, Singh SS, Kumar A, Menon A, King J, Langen R, Webster J, Scheraga RG, Rochon K, Mears J, Naga Prasad SV, Hatzoglou M, Chakraborty AA, and Dasarathy S
- Subjects
- Humans, Mice, Animals, Proteostasis, Muscle, Skeletal metabolism, Hypoxia metabolism, Sarcopenia metabolism, Pulmonary Disease, Chronic Obstructive complications
- Abstract
Nocturnal hypoxaemia, which is common in chronic obstructive pulmonary disease (COPD) patients, is associated with skeletal muscle loss or sarcopenia, which contributes to adverse clinical outcomes. In COPD, we have defined this as prolonged intermittent hypoxia (PIH) because the duration of hypoxia in skeletal muscle occurs through the duration of sleep followed by normoxia during the day, in contrast to recurrent brief hypoxic episodes during obstructive sleep apnoea (OSA). Adaptive cellular responses to PIH are not known. Responses to PIH induced by three cycles of 8 h hypoxia followed by 16 h normoxia were compared to those during chronic hypoxia (CH) or normoxia for 72 h in murine C2C12 and human inducible pluripotent stem cell-derived differentiated myotubes. RNA sequencing followed by downstream analyses were complemented by experimental validation of responses that included both unique and shared perturbations in ribosomal and mitochondrial function during PIH and CH. A sarcopenic phenotype characterized by decreased myotube diameter and protein synthesis, and increased phosphorylation of eIF2α (Ser51) by eIF2α kinase, and of GCN-2 (general controlled non-derepressed-2), occurred during both PIH and CH. Mitochondrial oxidative dysfunction, disrupted supercomplex assembly, lower activity of Complexes I, III, IV and V, and reduced intermediary metabolite concentrations occurred during PIH and CH. Decreased mitochondrial fission occurred during CH. Physiological relevance was established in skeletal muscle of mice with COPD that had increased phosphorylation of eIF2α, lower protein synthesis and mitochondrial oxidative dysfunction. Molecular and metabolic responses with PIH suggest an adaptive exhaustion with failure to restore homeostasis during normoxia. KEY POINTS: Sarcopenia or skeletal muscle loss is one of the most frequent complications that contributes to mortality and morbidity in patients with chronic obstructive pulmonary disease (COPD). Unlike chronic hypoxia, prolonged intermittent hypoxia is a frequent, underappreciated and clinically relevant model of hypoxia in patients with COPD. We developed a novel, in vitro myotube model of prolonged intermittent hypoxia with molecular and metabolic perturbations, mitochondrial oxidative dysfunction, and consequent sarcopenic phenotype. In vivo studies in skeletal muscle from a mouse model of COPD shared responses with our myotube model, establishing the pathophysiological relevance of our studies. These data lay the foundation for translational studies in human COPD to target prolonged, nocturnal hypoxaemia to prevent sarcopenia in these patients., (© 2022 The Authors. The Journal of Physiology © 2022 The Physiological Society.)
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- 2023
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21. A structure and function relationship study to identify the impact of the R721G mutation in the human mitochondrial lon protease.
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Sha Z, Montano MM, Rochon K, Mears JA, Deredge D, Wintrode P, Szweda L, Mikita N, and Lee I
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- Amino Acid Sequence, Amino Acid Substitution, Animals, B-Lymphocytes enzymology, Biocatalysis, Craniofacial Abnormalities enzymology, Craniofacial Abnormalities genetics, Enzyme Stability genetics, Eye Abnormalities enzymology, Eye Abnormalities genetics, Growth Disorders enzymology, Growth Disorders genetics, Hip Dislocation, Congenital enzymology, Hip Dislocation, Congenital genetics, Humans, Kinetics, Mice, Models, Molecular, Molecular Dynamics Simulation, Mutant Proteins chemistry, Mutant Proteins genetics, Mutant Proteins metabolism, Mutation, Missense, Osteochondrodysplasias enzymology, Osteochondrodysplasias genetics, Protease La metabolism, Pyruvate Dehydrogenase Acetyl-Transferring Kinase metabolism, Recombinant Proteins chemistry, Recombinant Proteins genetics, Recombinant Proteins metabolism, Structure-Activity Relationship, Substrate Specificity, Tooth Abnormalities enzymology, Tooth Abnormalities genetics, Mitochondria enzymology, Protease La chemistry, Protease La genetics
- Abstract
Lon is an ATP-dependent protease belonging to the "ATPase associated with diverse cellular activities" (AAA+) protein family. In humans, Lon is translated as a precursor and imported into the mitochondria matrix through deletion of the first 114 amino acid residues. In mice, embryonic knockout of lon is lethal. In humans, some dysfunctional lon mutations are tolerated but they cause a developmental disorder known as the CODAS syndrome. To gain a better understanding on the enzymology of human mitochondrial Lon, this study compares the structure-function relationship of the WT versus one of the CODAS mutants R721G to identify the mechanistic features in Lon catalysis that are affected. To this end, steady-state kinetics were used to quantify the difference in ATPase and ATP-dependent peptidase activities between WT and R721G. The K
m values for the intrinsic as well as protein-stimulated ATPase were increased whereas the kcat value for ATP-dependent peptidase activity was decreased in the R721G mutant. The mutant protease also displayed substrate inhibition kinetics. In vitro studies revealed that R721G did not degrade the endogenous mitochondrial Lon substrate pyruvate dehydrogenase kinase isoform 4 (PDK4) effectively like WT hLon. Furthermore, the pyruvate dehydrogenase complex (PDH) protected PDK4 from hLon degradation. Using hydrogen deuterium exchange/mass spectrometry and negative stain electron microscopy, structural perturbations associated with the R721G mutation were identified. To validate the in vitro findings under a physiologically relevant condition, the intrinsic stability as well as proteolytic activity of WT versus R721G mutant towards PDK 4 were compared in cell lysates prepared from immortalized B lymphocytes expressing the respective protease. The lifetime of PDK4 is longer in the mutant cells, but the lifetime of Lon protein is longer in the WT cells, which corroborate the in vitro structure-functional relationship findings., (Copyright © 2021 Elsevier Inc. All rights reserved.)- Published
- 2021
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22. Distribution of Dermacentor andersoni (Acari: Ixodidae) in Grassland Regions of Alberta, Canada.
- Author
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Lysyk TJ, Dergousoff SJ, Rochon K, Chilton NB, and Smith AM
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- Alberta, Animals, Female, Male, Population Density, Animal Distribution, Arachnid Vectors, Dermacentor, Grassland, Models, Statistical
- Abstract
The geographic distribution of the Rocky Mountain wood tick, Dermacentor andersoni Stiles, was determined in Alberta, Canada, by drag sampling at 86 and 89 sites during 2011 and 2012, respectively. Tick density and prevalence varied between years, averaging (range) 1.0 (0-26.2) and 5.9 (0-110) ticks/1,000 m2 in 2011 and 2012, respectively. Ticks were detected at 24.4% and 42.7% of the sites sampled in each respective year. Tick density and presence declined in a northerly direction to 51.6°N and in a westerly direction to ca. 113°W, except for a small area of high density at the edge of the Rocky Mountains in the southeastern portion of the province. Ticks were most abundant in the Dry Mixedgrass and Montane natural subregions and in areas with Brown Chernozemic, Regosol, and Solodized Solonetzic great soil groups. A logistic regression model indicated that tick presence was increased in the Dry Mixedgrass natural subregion and in regions with greater temperatures during the previous summer and normal winter precipitation but was reduced in areas with Dark Brown Chernozemic soils. The model will be useful for predicting tick presence and the associated risk of tick-borne diseases in the province., (© Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada, 2021.)
- Published
- 2021
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23. Sentinel surveillance of Lyme disease risk in Canada, 2019: Results from the first year of the Canadian Lyme Sentinel Network (CaLSeN).
- Author
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Guillot C, Badcock J, Clow K, Cram J, Dergousoff S, Dibernardo A, Evason M, Fraser E, Galanis E, Gasmi S, German GJ, Howse DT, Jardine C, Jenkins E, Koffi J, Kulkarni M, Lindsay LR, Lumsden G, McKay R, Moore K, Morshed M, Munn D, Nelder M, Nocera J, Ripoche M, Rochon K, Russell C, Slatculescu A, Talbot B, Thivierge K, Voordouw M, Bouchard C, and Leighton P
- Abstract
Background: Lyme disease is an emerging vector-borne zoonotic disease of increasing public health importance in Canada. As part of its mandate, the Canadian Lyme Disease Research Network (CLyDRN) launched a pan-Canadian sentinel surveillance initiative, the Canadian Lyme Sentinel Network (CaLSeN), in 2019., Objectives: To create a standardized, national sentinel surveillance network providing a real-time portrait of the evolving environmental risk of Lyme disease in each province., Methods: A multicriteria decision analysis (MCDA) approach was used in the selection of sentinel regions. Within each sentinel region, a systematic drag sampling protocol was performed in selected sampling sites. Ticks collected during these active surveillance visits were identified to species, and Ixodes spp. ticks were tested for infection with Borrelia burgdorferi , Borrelia miyamotoi , Anaplasma phagocytophilum , Babesia microti and Powassan virus., Results: In 2019, a total of 567 Ixodes spp. ticks ( I. scapularis [n=550]; I. pacificus [n=10]; and I. angustus [n=7]) were collected in seven provinces: British Columbia, Manitoba, Ontario, Québec, New Brunswick, Nova Scotia and Prince Edward Island. The highest mean tick densities (nymphs/100 m
2 ) were found in sentinel regions of Lunenburg (0.45), Montréal (0.43) and Granby (0.38). Overall, the Borrelia burgdorferi prevalence in ticks was 25.2% (0%-45.0%). One I. angustus nymph from British Columbia was positive for Babesia microti , a first for the province. The deer tick lineage of Powassan virus was detected in one adult I. scapularis in Nova Scotia., Conclusion: CaLSeN provides the first coordinated national active surveillance initiative for tick-borne disease in Canada. Through multidisciplinary collaborations between experts in each province, the pilot year was successful in establishing a baseline for Lyme disease risk across the country, allowing future trends to be detected and studied., Competing Interests: Competing interests: None.- Published
- 2020
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24. Passive and Active Surveillance for Ixodes scapularis (Acari: Ixodidae) in Saskatchewan, Canada.
- Author
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Chilton NB, Curry PS, Lindsay LR, Rochon K, Lysyk TJ, and Dergousoff SJ
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- Animals, Ixodes microbiology, Ixodes parasitology, Saskatchewan, Anaplasma phagocytophilum isolation & purification, Animal Distribution, Babesia microti isolation & purification, Borrelia burgdorferi isolation & purification, Epidemiological Monitoring veterinary, Ixodes physiology
- Abstract
Passive and active surveillance for the blacklegged tick, Ixodes scapularis Say, in the Canadian province of Saskatchewan was conducted over a 9-yr period (2009-2017). More than 26,000 ixodid ticks, representing 10 species, were submitted through passive surveillance. Most (97%) of these were the American dog tick, Dermacentor variabilis (Say). Of the 65 I. scapularis adults submitted, 75% were collected from dogs. Infection rates of Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti in I. scapularis were 12%, 8%, and 0%, respectively. Although the I. scapularis submitted by passive surveillance were collected from five of seven ecoregions in central and southern Saskatchewan, they were most frequent in the Moist Mixed Grassland and Aspen Parklands. In contrast, no I. scapularis were collected from the extensive field sampling conducted at multiple sites in different ecoregions across the province. Hence, there is no evidence of I. scapularis having established a breeding population in Saskatchewan. Nonetheless, continued surveillance for blacklegged ticks is warranted given their important role as a vector of medically and veterinary important pathogens, and because they have recently become established across much of the southern portions of the neighboring province of Manitoba., (© Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada, 2019.)
- Published
- 2020
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25. Role of container type, behavioural, and ecological factors in Aedes pupal production in Dhaka, Bangladesh: An application of zero-inflated negative binomial model.
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Islam S, Haque CE, Hossain S, and Rochon K
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- Animals, Bangladesh, Behavior, Cities, Ecosystem, Female, Humans, Models, Statistical, Mosquito Vectors, Water, Aedes, Human Activities, Mosquito Control methods, Pupa
- Abstract
The container-inhabiting Aedes mosquitoes are the major vectors transmitting dengue and several other arboviral diseases such as chikungunya and zika across the tropical world. Surveillance for immature Aedes, particularly pupae, is an effective tool for measuring dengue outbreak risk. While in Bangladesh, the greatest burden of dengue fever and dengue hemorrhagic fever cases has periodically been occurring since the first major outbreak in 2000, very limited research has yet been pursued to understand the dynamics of Aedes pupal production in this country. In this backdrop, this study was carried out to i) identify containers at household premises contributing to dengue vector productivity; ii) measure the extent of pupae productivity of household containers; and, iii) determine the effects of household ecological factors upon productivity of pupae in the city of Dhaka, Bangladesh. During the monsoon months of 2013, a total of 1,033 containers (674 wet and 363 dry) in 727 household premises in 12 wards of the city of Dhaka were inspected to measure container productivity and collect household ecological, and human behavioural data. The results reveal that the majority of immature mosquitoes (73.52% larvae and 84.91% pupae) developed in containers located outdoor that are used mostly for household chores. Plastic containers (57.55% of all immature mosquito-positive containers) used for household chores produce most of the immature mosquitos. The results of the zero-inflated negative binomial (ZINB) model reveal that pupae production significantly varies by container type (p-value = 0.0136) for the count regression group. However, when considering container size along with container type, container size is found significant for pupae production (p-value = 0.0041), showing that container size is confounded with the container type and the pupae production. Containers greater than 50 litres (L) are likely to produce 4.9 times more pupae than containers with <1L. Two household ecological factors are found to be significant (shade: p-value = 0.005 in the count regression group and type of water: p-value = 0.001 in the excess zero group) for pupae production. We found that containers with partial shade produce 4.6 times more pupae than without any shade, whereas in the excess zero group the expected number of observed zero pupae count is 86.5% lower in containers filled with rain water than those with tap water, tube-well water, ring well water and water from other sources. The most commonly used plastic-made containers (i.e., refrigerator trays, drums, buckets) and flower tubs/trays are the most abundant immature mosquito-positive containers. These findings would help the concerned authorities to formulate programs for changing human behaviour targeting the most productive containers for Aedes habitat management and vector control in the city of Dhaka, Bangladesh., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)
- Published
- 2019
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26. The role of 'filth flies' in the spread of antimicrobial resistance.
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Onwugamba FC, Fitzgerald JR, Rochon K, Guardabassi L, Alabi A, Kühne S, Grobusch MP, and Schaumburg F
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- Animals, Bacteria classification, Bacteria isolation & purification, Communicable Disease Control, Diptera anatomy & histology, Diptera growth & development, Disease Vectors, Epidemiological Monitoring, Humans, Insect Vectors anatomy & histology, Insect Vectors growth & development, Bacteria growth & development, Communicable Diseases transmission, Diptera microbiology, Drug Resistance, Bacterial, Insect Vectors microbiology
- Abstract
Background: 'Filth flies' feed and develop in excrement and decaying matter and can transmit enteric pathogens to humans and animals, leading to colonization and infection. Considering these characteristics, 'filth flies' are potential vectors for the spread of antimicrobial resistance (AMR). This review defines the role of flies in the spread of AMR and identifies knowledge gaps., Methods: The literature search (original articles, reviews indexed for PubMed) was restricted to the English language. References of identified studies were screened for additional sources., Results: 'Filth flies' are colonized with antimicrobial-resistant bacteria of clinical relevance. This includes extended spectrum beta-lactamase-, carbapenemase-producing and colistin-resistant (mcr-1 positive) bacteria. Resistant bacteria in flies often share the same genotypes with bacteria from humans and animals when their habitat overlap. The risk of transmission is most likely highest for enteric bacteria as they are shed in high concentration in excrements and are easily picked up by flies. 'Filth flies' can 'bio-enhance' the transmission of AMR as bacteria multiply in the digestive tract, mouthparts and regurgitation spots., Conclusion: To better understand the medical importance of AMR in flies, quantitative risk assessment models should be refined and fed with additional data (e.g. vectorial capacity, colonization dose). This requires targeted ecological, epidemiological and in vivo experimental studies., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2018
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27. A Risk Model for the Lyme Disease Vector Ixodes scapularis (Acari: Ixodidae) in the Prairie Provinces of Canada.
- Author
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Gabriele-Rivet V, Koffi JK, Pelcat Y, Arsenault J, Cheng A, Lindsay LR, Lysyk TJ, Rochon K, and Ogden NH
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- Alberta, Animals, Manitoba, Models, Biological, Risk, Saskatchewan, Animal Distribution, Arachnid Vectors physiology, Geographic Mapping, Ixodes physiology
- Abstract
Lyme disease is emerging in Canada due to geographic range expansion of the tick vector Ixodes scapularis Say. Recent areas of emergence include parts of the southeastern Canadian Prairie region. We developed a map of potential risk areas for future I. scapularis establishment in the Canadian Prairie Provinces. Six I. scapularis risk algorithms were developed using different formulations of three indices for environmental suitability: temperature using annual cumulative degree-days > 0 °C (DD > 0 °C; obtained from Moderate Resolution Imaging Spectroradiometer satellite data as an index of conditions that allow I. scapularis to complete its life cycle), habitat as a combined geolayer of forest cover and agricultural land use, and rainfall. The relative performance of these risk algorithms was assessed using receiver-operating characteristic (ROC) area under the curve (AUC) analysis with data on presence-absence of I. scapularis obtained from recent field surveillance in the Prairie Provinces accumulated from a number of sources. The ROC AUC values for the risk algorithms were significantly different (P < 0.01). The algorithm with six categories of DD > 0 °C, habitat as a simple dichotomous variable of presence or absence of forest, and normalized rainfall had the highest AUC of 0.74, representing "fair to good" performance of the risk algorithm. This algorithm had good (>80%) sensitivity in predicting positive I. scapularis surveillance sites, but low (50%) specificity as expected in this region where not all environmentally suitable habitats are expected to be occupied. Further prospective studies are needed to validate and perhaps improve the risk algorithm., (© Crown copyright 2017.)
- Published
- 2017
- Full Text
- View/download PDF
28. Synthesis of Gly-ψ[(Z)CF═CH]-Phe, a Fluoroalkene Dipeptide Isostere, and Its Incorporation into a Leu-enkephalin Peptidomimetic.
- Author
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Nadon JF, Rochon K, Grastilleur S, Langlois G, Dao TT, Blais V, Guérin B, Gendron L, and Dory YL
- Subjects
- Animals, Cell Line, Transformed, Cell Line, Tumor, Dipeptides chemistry, Enkephalin, Leucine analogs & derivatives, Green Fluorescent Proteins genetics, Green Fluorescent Proteins metabolism, Humans, Male, Mice, Peptidomimetics pharmacology, Phosphorylation drug effects, Rats, Receptors, Opioid, delta genetics, Transfection, Vas Deferens drug effects, Vas Deferens metabolism, Binding, Competitive drug effects, Enkephalin, Leucine chemistry, Hydrocarbons, Fluorinated chemical synthesis, Hydrocarbons, Fluorinated pharmacology, Peptidomimetics chemical synthesis, Receptors, Opioid, delta metabolism
- Abstract
A new Leu-enkephalin peptidomimetic designed to explore the hydrogen bond acceptor ability of the third peptide bond has been prepared and studied. This new analog is produced by replacing the third amide of Leu-enkephalin with a fluoroalkene. An efficient and innovative synthesis of the corresponding dipeptide surrogate Fmoc-Gly-ψ[(Z)CF═CH]-Phe-OH is described. The key step involves the alkylation of a tin dienolate from the less hindered face of its chiral sulfonamide auxiliary derived from camphor. Once its synthesis was complete, its incorporation into the peptidomimetic sequence was achieved on a solid support with chlorotrityl resin following the Fmoc strategy. The peptidomimetic was characterized using competition binding with [
125 I]-deltorphin I on membrane extracts of HEK293 cells expressing the mouse delta opioid receptor (DOPr) and based on its abilities to inhibit the electrically induced contractions of the mouse vas deferens and to activate the ERK1/2 signaling pathway in DRGF11/DOPr-GFP cells. Together with our previous observations, our findings strongly suggest that the third amide bond of Leu-enkephalin primarily acts as a hydrogen bond acceptor in DOPr. Consequently, this amide bond can be successfully replaced by an ester, a thioamide, or a fluoroalkene without greatly impacting the binding or biological activity of the corresponding analogs. The lipophilicity (LogD7.4 ) of the active analog was also measured. It appears that fluoroalkenes are almost as efficient at increasing the lipophilicity as normal alkenes.- Published
- 2017
- Full Text
- View/download PDF
29. The increasing risk of Lyme disease in Canada.
- Author
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Bouchard C, Leonard E, Koffi JK, Pelcat Y, Peregrine A, Chilton N, Rochon K, Lysyk T, Lindsay LR, and Ogden NH
- Subjects
- Animal Distribution, Animals, Canada epidemiology, Communicable Diseases, Emerging epidemiology, Dog Diseases epidemiology, Dogs, Ixodes physiology, Communicable Diseases, Emerging veterinary, Dog Diseases microbiology, Lyme Disease veterinary
- Abstract
There is an increasing risk of Lyme disease in Canada due to range expansion of the tick vector, Ixodes scapularis. The objectives of this article are to i) raise public awareness with the help of veterinarians on the emerging and expanding risk of Lyme disease across Canada, ii) review the key clinical features of Lyme disease in dogs, and iii) provide recommendations for veterinarians on the management of Lyme disease in dogs.
- Published
- 2015
30. Systematic replacement of amides by 1,4-disubstituted[1,2,3]triazoles in Leu-enkephalin and the impact on the delta opioid receptor activity.
- Author
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Proteau-Gagné A, Rochon K, Roy M, Albert PJ, Guérin B, Gendron L, and Dory YL
- Subjects
- Binding, Competitive, Enkephalin, Leucine pharmacology, Hydrogen Bonding, Inhibitory Concentration 50, Molecular Structure, Peptidomimetics, Receptors, Opioid, delta drug effects, Amides chemistry, Enkephalin, Leucine chemistry, Receptors, Opioid, delta chemistry, Triazoles chemistry
- Abstract
Using Cu(I)-catalyzed azide-alkyne cycloaddition in a mixed classical organic phase and solid phase peptide synthesis approach, we synthesized four analogs of Leu-enkephalin to systematically replace amides by 1,4-disubstituted[1,2,3]triazoles. The peptidomimetics obtained were characterized by competitive binding, contractility assays and ERK1/2 phosphorylation. The present study reveals that the analog bearing a triazole between Phe and Leu retains some potency, more than all the others, suggesting that the hydrogen bond acceptor capacity of the last amide of Leu-enkephalin is essential for the biological activity of the peptide., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
31. Preparation and evaluation at the delta opioid receptor of a series of linear leu-enkephalin analogues obtained by systematic replacement of the amides.
- Author
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Rochon K, Proteau-Gagné A, Bourassa P, Nadon JF, Côté J, Bournival V, Gobeil F Jr, Guérin B, Dory YL, and Gendron L
- Subjects
- Amides pharmacology, Animals, Depsipeptides chemical synthesis, Depsipeptides pharmacology, Enkephalin, Leucine chemical synthesis, Esters chemical synthesis, Esters pharmacology, Hydrogen Bonding, Male, Mice, Peptidomimetics chemical synthesis, Receptors, Opioid, delta drug effects, Solid-Phase Synthesis Techniques methods, Vas Deferens drug effects, Enkephalin, Leucine analogs & derivatives, Peptidomimetics pharmacology, Receptors, Opioid, delta metabolism
- Abstract
Leu-enkephalin analogues, in which the amide bonds were sequentially and systematically replaced either by ester or N-methyl amide bonds, were prepared using classical organic chemistry as well as solid phase peptide synthesis (SPPS). The peptidomimetics were characterized using competition binding, ERK1/2 phosphorylation, receptor internalization, and contractility assays to evaluate their pharmacological profile over the delta opioid receptor (DOPr). The lipophilicity (LogD7.4) and plasma stability of the active analogues were also measured. Our results revealed that the last amide bond can be successfully replaced by either an ester or an N-methyl amide bond without significantly decreasing the biological activity of the corresponding analogues when compared to Leu-enkephalin. The peptidomimetics with an N-methyl amide function between residues Phe and Leu were found to be more lipophilic and more stable than Leu-enkephalin. Findings from the present study further revealed that the hydrogen-bond donor properties of the fourth amide of Leu-enkephalin are not important for its biological activity on DOPr. Our results show that the systematic replacement of amide bonds by isosteric functions represents an efficient way to design and synthesize novel peptide analogues with enhanced stability. Our findings further suggest that such a strategy can also be useful to study the biological roles of amide bonds.
- Published
- 2013
- Full Text
- View/download PDF
32. Arthropod Surveillance Programs: Basic Components, Strategies, and Analysis.
- Author
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Cohnstaedt LW, Rochon K, Duehl AJ, Anderson JF, Barrera R, Su NY, Gerry AC, Obenauer PJ, Campbell JF, Lysyk TJ, and Allan SA
- Abstract
Effective entomological surveillance planning stresses a careful consideration of methodology, trapping technologies, and analysis techniques. Herein, the basic principles and technological components of arthropod surveillance plans are described, as promoted in the symposium "Advancements in arthropod monitoring technology, techniques, and analysis" presented at the 58th annual meeting of the Entomological Society of America in San Diego, CA. Interdisciplinary examples of arthropod monitoring for urban, medical, and veterinary applications are reviewed. Arthropod surveillance consists of the three components: 1) sampling method, 2) trap technology, and 3) analysis technique. A sampling method consists of selecting the best device or collection technique for a specific location and sampling at the proper spatial distribution, optimal duration, and frequency to achieve the surveillance objective. Optimized sampling methods are discussed for several mosquito species (Diptera: Culicidae) and ticks (Acari: Ixodidae). The advantages and limitations of novel terrestrial and aerial insect traps, artificial pheromones and kairomones are presented for the capture of red flour beetle (Coleoptera: Tenebrionidae), small hive beetle (Coleoptera: Nitidulidae), bed bugs (Hemiptera: Cimicidae), and Culicoides (Diptera: Ceratopogonidae) respectively. After sampling, extrapolating real world population numbers from trap capture data are possible with the appropriate analysis techniques. Examples of this extrapolation and action thresholds are given for termites (Isoptera: Rhinotermitidae) and red flour beetles.
- Published
- 2012
- Full Text
- View/download PDF
33. Exploring the Backbone of Enkephalins To Adjust Their Pharmacological Profile for the δ-Opioid Receptor.
- Author
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Proteau-Gagné A, Bournival V, Rochon K, Dory YL, and Gendron L
- Subjects
- Animals, Binding, Competitive drug effects, Cell Line, Enkephalin, Leucine analogs & derivatives, Enkephalin, Leucine chemical synthesis, Enkephalin, Leucine pharmacology, Enkephalin, Methionine analogs & derivatives, Enkephalin, Methionine chemical synthesis, Enkephalin, Methionine pharmacology, Indicators and Reagents, Mice, Mitogen-Activated Protein Kinases metabolism, Models, Molecular, Molecular Conformation, Receptors, Opioid, delta agonists, Receptors, Opioid, delta metabolism, Signal Transduction drug effects, Structure-Activity Relationship, Enkephalins chemistry, Enkephalins pharmacology, Receptors, Opioid, delta drug effects
- Abstract
The role of each of the four amide bonds in Leu(5)-enkephalin was investigated by systematically and sequentially replacing each with its corresponding trans-alkene. Six Leu(5)-enkephalin analogs based on six dipeptide surrogates and two Met(5)-enkephalin analogs were synthesized and thoroughly tested using a δ-opioid receptor internalization assay, an ERK1/2 activation assay, and a competition binding assay to evaluate their biological properties. We observed that an E-alkene can efficiently replace the first amide bond of Leu(5)- and Met(5)-enkephalin without significantly affecting biological activity. By contrast, the second amide bond was found to be highly sensitive to the same modification, suggesting that it is involved in biologically essential intra- or intermolecular interactions. Finally, we observed that the affinity and activity of analogs containing an E-alkene at either the third or fourth position were partially reduced, indicating that these amide bonds are less important for these intra- or intermolecular interactions. Overall, our study demonstrates that the systematic and sequential replacement of amide bonds by E-alkene represents an efficient way to explore peptide backbones.
- Published
- 2010
- Full Text
- View/download PDF
34. Experimental evaluation of Musca domestica (Diptera: Muscidae) as a vector of Newcastle disease virus.
- Author
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Watson DW, Niño EL, Rochon K, Denning S, Smith L, and Guy JS
- Subjects
- Animals, Chickens virology, Disease Vectors, Houseflies virology, Newcastle Disease transmission, Newcastle disease virus isolation & purification
- Abstract
House flies, Musca domestica L. (Diptera: Muscidae), were examined for their ability to harbor and transmit Newcastle disease virus (family Paramyxoviridae, genus Avulavirus, NDV) by using a mesogenic NDV strain. Laboratory-reared flies were experimentally exposed to NDV (Roakin strain) by allowing flies to imbibe an inoculum consisting of chicken embryo-propagated virus. NDV was detected in dissected crops and intestinal tissues from exposed flies for up to 96 and 24 h postexposure, respectively; no virus was detected in crops and intestines of sham-exposed flies. The potential of the house fly to directly transmit NDV to live chickens was examined by placing 14-d-old chickens in contact with NDV-exposed house flies 2 h after flies consumed NDV inoculum. NDV-exposed house flies contained approximately 10(4) 50% infectious doses (ID50) per fly, but no transmission of NDV was observed in chickens placed in contact with exposed flies at densities as high as 25 flies per bird. Subsequent dose-response studies demonstrated that oral exposure, the most likely route for fly-to-chicken transmission, required an NDV (Roakin) dose > or =10(6) ID50. These results indicate that house flies are capable of harboring NDV (Roakin) but that they are poor vectors of the virus because they carry an insufficient virus titer to cause infection.
- Published
- 2007
- Full Text
- View/download PDF
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