Schlüsselwörter
(Deutsch)
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Infektionserkrankung, D. nodosus, Moderhinke, Schafe, Resistenz, Empfänglichkeit, Selektion, Bekämpfung, Antibiotika
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Schlüsselwörter
(Englisch)
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Infectious disease, D. nodosus, footrot, sheep, resistance, susceptibility, selection, control, antibiotics
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Schlüsselwörter
(Französisch)
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maladie infectieuse, D. nodosus, pied, mouton, résistance, susceptibilité, sélection, contrôle, antibiotiques
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Kurzbeschreibung
(Deutsch)
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Moderhinke infolge einer Infektion mit Dichelobacter nodosus ist als wesentliche Ursache von Lahmheiten beim Schaf weit verbreitet und stellt in vielen Schweizer Beständen ein dauerndes Problem dar. Zur Bekämpfung werden derzeit Klauenschnitt, Klauenbäder, spezifische Impfungen und Antibiotika eingesetzt. Neue mikrobiologische Diagnostikmethoden zur Früherkennung von virulenten Erregerstämmen haben bestätigt, dass innerhalb betroffener Herden immer wieder Tiere mit vermutlich genetisch bedingter geringer und hoher Empfänglichkeit gegenüber einer Infektion auftreten. Die Studie sieht einen DNA-basierten Vergleich von Weissen Alpenschafen mit bekanntem Moderhinke- und Infektionsstatus vor. Somit könnten Genomregionen identifiziert werden, welche die variable Moderhinke-Empfänglichkeit oder Resistenz bestimmen. Die Resultate sollen eine Grundlage schaffen, um zukünftig neben bestehenden Massnahmen auch züchterisch die Anzahl an Moderhinke erkrankter Schafe zu verringern und dadurch auch einem vermehrten Einsatz von Antibiotika vorzubeugen.
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Kurzbeschreibung
(Englisch)
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Footrot is a highly contagious disease caused by Dichelobacter nodosus, which is the major cause of lameness in sheep occurring continuous in many Swiss sheep flocks. Besides foot trimming and foot bathing in disinfectant solutions, vaccination and/or antibiotic treatment are used as traditional footrot control measures. New microbiologic diagnostic methods for early diagnosis of virulent strains confirmed that within affected flocks usually some animals resist the development of clinical signs (healthy carriers) probably due to a genetically determined resistance against the infection. The study aims at a DNA-based comparison of Swiss White Alpine sheep with known footrot and infectious status. Thereby, genomic regions associated with decreased susceptibility or resistance to footrot could be identified. These results will provide a basis for additional breeding based measures within the frame of a future Swiss footrot control program to reduce the number of sheep severely affected with footrot and to prevent an increase of antibiotic treatments.
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Projektziele
(Englisch)
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The goal of the study is to exploiting the host’s genetic susceptibility/resistance to infections with virulent strains of D. nodosus causing clinical signs of footrot. Until now, linking footrot phenotype to genetic markers of the sheep has not yet been undertaken in any Swiss breed. The aim of this study is to investigate if existing significant genetic markers are related to clinical signs of footrot and the presence of an infection with virulent strains of D. nodosus in a cohort of Swiss White Alpine sheep, a breed to which nearly every second sheep in Switzerland belongs. This study should be considered as an initial attempt to go towards identifying genetic markers that are associated with footrot resistance in sheep which will be useful for future breeding decisions. However, we recognize that the current genetic test (Lincoln University footrot gene test) that is already available from New Zealand for detecting footrot resistance (Hickford et al. 2004) is most likely not be applicable to Swiss breeds because, a) having polymorphisms that are not recognized by the test, and b) existing test categories not conferring the same degree of resistance under Swiss conditions.
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Abstract
(Englisch)
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The development and use of a genetic screening for footrot resistance has potentially considerable advantages. First, animals under selection do not need to be exposed to the disease to determine whether they are genetically susceptible or not. Second, genotype information offers a practical alternative to laborious phenotypic scoring and disease exposure protocols. Molecular techniques to identify resistant animals would help Swiss breeders to select for footrot resistance. This would provide an important alternative tool for control of footrot in sheep in addition to the established strategies.
This study should help to identify genetic markers that are associated with footrot resistance in Swiss White Alpine sheep which could be used immediately for marker-assisted selection based breeding decisions in the future. This would potentially add a currently unavailable tool in addition to the existing portfolio of measures to control footrot in Switzerland.
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Arbeitsvorgang/Stand der Arbeiten
(Englisch)
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In this study, we genotyped 373 Swiss White Alpine sheep, using the ovine high-density 600k SNP chip, in order to run a DNA-based comparison of individuals with known clinical footrot status. We performed a case–control genome-wide association study, which revealed a genome-wide significant association for SNP rs418747104 on ovine chromosome 2 at 81.2 Mb. The three best associated SNP markers were located at the MPDZ gene, which codes for the multiple PDZ domain crumbs cell polarity complex component protein, also known as multi-PDZ domain protein 1 (MUPP1). This protein is possibly involved in maintaining the barrier function and integrity of tight junctions. Therefore, we speculate that individuals carrying MPDZ variants may differ in their footrot resistance/susceptibility due to modified horn and interdigital skin integrity. In conclusion, our study reveals that MPDZ might represent a functional candidate gene, and further research is needed to explore its role in footrot affected sheep.
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