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Edwin Claerebout - One of the best experts on this subject based on the ideXlab platform.
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Dermal immune responses against Psoroptes Ovis in two cattle breeds and effects of anti-inflammatory dexamethasone treatment on the development of psoroptic mange
Veterinary Research, 2021Co-Authors: Zhenzhen Chen, Edwin Claerebout, Koen Chiers, Mathilde Pas, Bart Pardon, Wouter Mol, Stijn Casaert, Nathalie Wilde, Luc Duchateau, Peter GeldhofAbstract:Psoroptic mange is a common disease of livestock, caused by Psoroptes Ovis . Compared to Holstein–Friesian (HF) cattle, the Belgian Blue (BB) cattle breed is highly susceptible to the infestation. However, the mechanism for this difference is still unclear. To determine the factors responsible for this breed susceptibility, the immune response to P. Ovis was studied in experimentally infested BB and HF cattle, using clinical signs, histology, immunohistochemical profiling and gene expression analysis of skin biopsies. The mite numbers and lesion area of BB cattle were greater than in HF during the whole study period. Significant influxes of eosinophils in the epidermis and dermis were detected in comparison with the pre-infestation samples in both breeds, with significantly higher eosinophils in BB at 6 weeks post infestation (wpi). Mast cell numbers were unaffected at all stages of infestation in HF, but were significantly elevated relative to pre-infestation in BB cattle at 2 and 6 wpi. The more pronounced cutaneous eosinophilia and higher IL-4 levels at 6 wpi in BB cattle suggest that a Th2-type immune response is underlying the higher susceptibility of the BB breed. In naturally infested BB cattle, development of the psoroptic mange lesions and eosinophils and CD3+ T cell areas were severely depressed after anti-inflammatory treatment with dexamethasone. Together, these results suggest that a stronger Th2-type immune response to P. Ovis causes the skin lesions in psoroptic mange in BB cattle and that local anti-inflammatory treatment could potentially be an alternative to control the pathology caused by this parasite.
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new insights into the use of a mite count reduction test for the detection of therapeutic acaricide efficacy in Psoroptes Ovis in cattle
International Journal for Parasitology-Drugs and Drug Resistance, 2020Co-Authors: Wouter Van Mol, Edwin Claerebout, Stijn Casaert, Peter Geldhof, B LeveckeAbstract:When used for the evaluation of drug efficacy against Psoroptes Ovis, the diagnostic performance of different sampling strategies for a mite count reduction test (MCRT) remains unclear. In the present study, a novel simulation framework was constructed that accounted for relevant biological features of P. Ovis infestations in cattle and that was parameterized with field data from 16 farms (154 animals). Second, this framework was applied to explore the impact of study specific factors (number of animals, number of sampled lesions, and number of scrapings per lesion) and biological factors (mite infestation intensity and size of lesions) on the diagnostic performance of MCRT. Its outcome provided a basis to determine the diagnostic performance of MCRT when it was applied according to the World Association for the Advancement in Veterinary Parasitology (WAAVP) and the European Medicine Agency (EMA) guidelines, and to formulate recommendations to ensure a good diagnostic performance of the MCRT. For both guidelines, the MCRT allowed to correctly detect (power 80%) reduced and normal efficacy when the therapeutic efficacy was <70%, and ≥95%, respectively. The results highlighted a reliable diagnostic performance of the MCRT when performed as recommended by WAAVP and EMA for the detection of normal drug efficacy. When used for the detection of reduced efficacy, therapeutic efficacies between 70% and 90% could not be detected with sufficient reliability. The diagnostic performance can be improved by increasing the total number of skin scrapings (increasing the number of animals, number of sampled lesions and/or number of samples per lesion). In order to help researchers and veterinarians to optimize the design of the MCRT to their field settings, the findings were translated into a simple tool.
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Resistance against macrocyclic lactones in Psoroptes Ovis in cattle
Parasites & Vectors, 2020Co-Authors: Wouter Van Mol, Zhenzhen Chen, Stijn Casaert, Nathalie Wilde, Luc Duchateau, Marieke Vanhecke, Edwin ClaereboutAbstract:Background Psoroptic mange is an important disease in Belgian Blue cattle. Treatment failure of macrocyclic lactones against Psoroptes Ovis has been reported, but clear evidence of in vivo resistance is lacking. This study assessed the efficacy of macrocyclic lactone products on 16 beef farms in Belgium and the Netherlands in vivo and in vitro . Methods On each farm a group of animals ( n = 7–14) with psoroptic mange was treated with two subcutaneous injections of a macrocyclic lactone product with 7–10 days interval (15 farms) or a single injection with a long-acting macrocyclic lactone (1 farm). In vivo efficacy was assessed by the reduction in mite counts, clinical index (proportion of the body surface affected by lesions), the proportion of the animals with negative mite counts after the first treatment round and the number of treatment rounds needed to obtain zero mites counts in all animals. A mite population was categorized as sensitive when the mite count reduction after the first treatment round > 95% and the lower limit of the uncertainty interval > 90%. Resistance was detected when both parameters were below their threshold and suspected when one parameter was too low. In vitro knockdown and mortality were evaluated in a contact test. Results The proportion of the animals with negative mite counts after the first treatment round varied from 0 to 80%. All farms needed two or more treatments rounds to obtain zero mite counts on all animals. Clinical index only started to reduce after the second treatment round. Mite populations from three farms were categorized as sensitive, one as suspected resistant and 12 as resistant. No correlation was found between in vitro lethal dose 50 and knockdown dose 50 values and in vivo efficacy parameters. Conclusions Unambiguous treatment failure was detected on 12 out of 16 farms, confirming the presence of macrocyclic lactone resistance on Belgian Blue beef farms. In vitro parameters could not discriminate the farms based on their in vivo sensitivity. The mean reduction in mite counts and the lower limit of the confidence interval are proposed as parameters to identify acaricide resistance.
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Resistance against macrocyclic lactones in Psoroptes Ovis in cattle
Parasites & vectors, 2020Co-Authors: Wouter Van Mol, Zhenzhen Chen, Stijn Casaert, Nathalie Wilde, Luc Duchateau, Marieke Vanhecke, Edwin ClaereboutAbstract:Psoroptic mange is an important disease in Belgian Blue cattle. Treatment failure of macrocyclic lactones against Psoroptes Ovis has been reported, but clear evidence of in vivo resistance is lacking. This study assessed the efficacy of macrocyclic lactone products on 16 beef farms in Belgium and the Netherlands in vivo and in vitro. On each farm a group of animals (n = 7–14) with psoroptic mange was treated with two subcutaneous injections of a macrocyclic lactone product with 7–10 days interval (15 farms) or a single injection with a long-acting macrocyclic lactone (1 farm). In vivo efficacy was assessed by the reduction in mite counts, clinical index (proportion of the body surface affected by lesions), the proportion of the animals with negative mite counts after the first treatment round and the number of treatment rounds needed to obtain zero mites counts in all animals. A mite population was categorized as sensitive when the mite count reduction after the first treatment round > 95% and the lower limit of the uncertainty interval > 90%. Resistance was detected when both parameters were below their threshold and suspected when one parameter was too low. In vitro knockdown and mortality were evaluated in a contact test. The proportion of the animals with negative mite counts after the first treatment round varied from 0 to 80%. All farms needed two or more treatments rounds to obtain zero mite counts on all animals. Clinical index only started to reduce after the second treatment round. Mite populations from three farms were categorized as sensitive, one as suspected resistant and 12 as resistant. No correlation was found between in vitro lethal dose 50 and knockdown dose 50 values and in vivo efficacy parameters. Unambiguous treatment failure was detected on 12 out of 16 farms, confirming the presence of macrocyclic lactone resistance on Belgian Blue beef farms. In vitro parameters could not discriminate the farms based on their in vivo sensitivity. The mean reduction in mite counts and the lower limit of the confidence interval are proposed as parameters to identify acaricide resistance.
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acaricidal activity of plant derived essential oil components against Psoroptes Ovis in vitro and in vivo
Parasites & Vectors, 2019Co-Authors: Zhenzhen Chen, Luc Duchateau, Marieke Vanhecke, Wouter Van Mol, Edwin ClaereboutAbstract:Treatment of Psoroptes Ovis in cattle is limited to topical acaricides or systemic treatment with macrocyclic lactones. Treatment failure of macrocyclic lactones has been reported. The aim of this study was to evaluate a potential alternative treatment against P. Ovis. The acaricidal activity against P. Ovis of four plant-derived essential oil components, i.e. geraniol, eugenol, 1,8-cineol and carvacrol, was assessed in vitro and in vivo. In vitro contact, fumigation and residual bioassays were performed. In addition, 12 Belgium Blue cattle were artificially infested and treated topically once a week for three successive weeks with carvacrol in Tween-80 (treatment group) or with Tween-80 alone (control). The efficacy of carvacrol was determined by the reduction in lesion size and mite counts. Six additional animals were topically treated with carvacrol to assess local adverse reactions. Three components showed a concentration-dependent acaricidal activity in a contact assay, with LC50 of 0.56, 0.38 and 0.26% at 24 h for geraniol, eugenol, and carvacrol, respectively. However, 1,8-cineol showed no activity at any of the tested concentrations in a contact bioassay. In a fumigation bioassay, carvacrol killed all mites within 50 min after treatment, whereas geraniol, eugenol and 1,8-cineol needed 90 to 150 min. Following a 72 h incubation period in a residual bioassay, carvacrol killed all mites after 4 h of exposure to LC90, while geraniol and eugenol killed all mites only after 8 h exposure. Based on these results, carvacrol was further assessed in vivo. Mite counts in the treatment group were reduced by 98.5 ± 2.4% at 6 weeks post-treatment, while in the control group the mite population had increased. Topical application of carvacrol only caused mild and transient erythema 20 min after treatment. No other side effects were observed. Considering the strong acaricidal activity of carvacrol in vitro and in vivo and the mild and transient local side effects, carvacrol shows potential as an acaricidal agent in the treatment of P. Ovis in cattle.
J F Huntley - One of the best experts on this subject based on the ideXlab platform.
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the use of a Psoroptes Ovis serodiagnostic test for the analysis of a natural outbreak of sheep scab
Parasites & Vectors, 2012Co-Authors: Stewart T. G. Burgess, Alasdair J. Nisbet, Fiona Kenyon, David Frew, Francesca Nunn, G T Innocent, J F HuntleyAbstract:Background Sheep scab is a highly contagious disease of sheep caused by the ectoparasitic mite Psoroptes Ovis. The disease is endemic in the UK and has significant economic impact through its effects on performance and welfare. Diagnosis of sheep scab is achieved through observation of clinical signs e.g. itching, pruritis and wool loss and ultimately through the detection of mites in skin scrapings. Early stages of infestation are often difficult to diagnose and sub-clinical animals can be a major factor in disease spread. The development of a diagnostic assay would enable farmers and veterinarians to detect disease at an early stage, reducing the risk of developing clinical disease and limiting spread.
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host transcription factors in the immediate pro inflammatory response to the parasitic mite Psoroptes Ovis
PLOS ONE, 2011Co-Authors: Stewart T. G. Burgess, Alasdair J. Nisbet, Craig A Watkins, Tom N Mcneilly, J F HuntleyAbstract:Background: Sheep scab, caused by infestation with the ectoparasitic mite Psoroptes Ovis, results in the rapid development of cutaneous inflammation and leads to the crusted skin lesions characteristic of the disease. We described previously the global host transcriptional response to infestation with P. Ovis, elucidating elements of the inflammatory processes which lead to the development of a rapid and profound immune response. However, the mechanisms by which this response is instigated remain unclear. To identify novel methods of intervention a better understanding of the early events involved in triggering the immune response is essential. The objective of this study was to gain a clearer understanding of the mechanisms and signaling pathways involved in the instigation of the immediate pro-inflammatory response. Results: Through a combination of transcription factor binding site enrichment and pathway analysis we identified key roles for a number of transcription factors in the instigation of cutaneous inflammation. In particular, defined roles were elucidated for the transcription factors NF-kB and AP-1 in the orchestration of the early pro-inflammatory response, with these factors being implicated in the activation of a suite of inflammatory mediators. Conclusions: Interrogation of the host temporal response to P. Ovis infestation has enabled the further identification of the mechanisms underlying the development of the immediate host pro-inflammatory response. This response involves key regulatory roles for the transcription factors NF-kB and AP-1. Pathway analysis demonstrated that the activation of these transcription factors may be triggered following a host LPS-type response, potentially involving TLR4-signalling and also lead to the intriguing possibility that this could be triggered by a P. Ovis allergen.
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generation analysis and functional annotation of expressed sequence tags from the ectoparasitic mite Psoroptes Ovis
Parasites & Vectors, 2011Co-Authors: Stewart T. G. Burgess, Alasdair J. Nisbet, Fiona Kenyon, J F HuntleyAbstract:Background Sheep scab is caused by Psoroptes Ovis and is arguably the most important ectoparasitic disease affecting sheep in the UK. The disease is highly contagious and causes and considerable pruritis and irritation and is therefore a major welfare concern. Current methods of treatment are unsustainable and in order to elucidate novel methods of disease control a more comprehensive understanding of the parasite is required. To date, no full genomic DNA sequence or large scale transcript datasets are available and prior to this study only 484 P. Ovis expressed sequence tags (ESTs) were accessible in public databases.
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transcriptomic analysis of the temporal host response to skin infestation with the ectoparasitic mite Psoroptes Ovis
BMC Genomics, 2010Co-Authors: Stewart T. G. Burgess, Alasdair J. Nisbet, David Frew, Francesca Nunn, Craig A Watkins, Tom N Mcneilly, J F HuntleyAbstract:Background Infestation of ovine skin with the ectoparasitic mite Psoroptes Ovis results in a rapid cutaneous immune response, leading to the crusted skin lesions characteristic of sheep scab. Little is known regarding the mechanisms by which such a profound inflammatory response is instigated and to identify novel vaccine and drug targets a better understanding of the host-parasite relationship is essential. The main objective of this study was to perform a combined network and pathway analysis of the in vivo skin response to infestation with P. Ovis to gain a clearer understanding of the mechanisms and signalling pathways involved.
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transcriptomic analysis of the temporal host response to skin infestation with the ectoparasitic mite Psoroptes Ovis
BMC Genomics, 2010Co-Authors: Stewart T. G. Burgess, Alasdair J. Nisbet, David Frew, Francesca Nunn, Craig A Watkins, Tom N Mcneilly, J F HuntleyAbstract:Infestation of ovine skin with the ectoparasitic mite Psoroptes Ovis results in a rapid cutaneous immune response, leading to the crusted skin lesions characteristic of sheep scab. Little is known regarding the mechanisms by which such a profound inflammatory response is instigated and to identify novel vaccine and drug targets a better understanding of the host-parasite relationship is essential. The main objective of this study was to perform a combined network and pathway analysis of the in vivo skin response to infestation with P. Ovis to gain a clearer understanding of the mechanisms and signalling pathways involved. Infestation with P. Ovis resulted in differential expression of 1,552 genes over a 24 hour time course. Clustering by peak gene expression enabled classification of genes into temporally related groupings. Network and pathway analysis of clusters identified key signalling pathways involved in the host response to infestation. The analysis implicated a number of genes with roles in allergy and inflammation, including pro-inflammatory cytokines (IL1A, IL1B, IL6, IL8 and TNF) and factors involved in immune cell activation and recruitment (SELE, SELL, SELP, ICAM1, CSF2, CSF3, CCL2 and CXCL2). The analysis also highlighted the influence of the transcription factors NF-kB and AP-1 in the early pro-inflammatory response, and demonstrated a bias towards a Th2 type immune response. This study has provided novel insights into the signalling mechanisms leading to the development of a pro-inflammatory response in sheep scab, whilst providing crucial information regarding the nature of mite factors that may trigger this response. It has enabled the elucidation of the temporal patterns by which the immune system is regulated following exposure to P. Ovis, providing novel insights into the mechanisms underlying lesion development. This study has improved our existing knowledge of the host response to P. Ovis, including the identification of key parallels between sheep scab and other inflammatory skin disorders and the identification of potential targets for disease control.
Alasdair J. Nisbet - One of the best experts on this subject based on the ideXlab platform.
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Gene silencing by RNA interference in the ectoparasitic mite, Psoroptes Ovis
Veterinary Research, 2018Co-Authors: Edward J. Marr, Harry W. Wright, Alasdair J. Nisbet, Neil D. Sargison, Stewart T. G. BurgessAbstract:The presence of components of the RNA interference (RNAi) pathway in Psoroptes Ovis , an ectoparasitic mite responsible for psoroptic mange, was investigated through interrogation of the P. Ovis genome. Homologues of transcripts representing critical elements for achieving effective RNAi in the mite, Tetranychus urticae and the model organisms Caenorhabditis elegans and Drosophila melanogaster were identified and, following the development of a non-invasive immersion method of double stranded RNA delivery, gene silencing by RNAi was successfully demonstrated in P. Ovis. Significant reductions in transcript levels were achieved for three target genes which encode the Group 2 allergen (Pso o 2), mu-class glutathione S -transferase ( Po GST-mu1) and beta-tubulin ( Po βtub). This is the first demonstration of RNAi in P. Ovis and provides a mechanism for mining transcriptomic and genomic datasets for novel control targets against this economically important ectoparasite.
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Host Transcription Factors in the Immediate Pro- Inflammatory Response to the Parasitic Mite Psoroptes Ovis
2013Co-Authors: Stewart T. G. Burgess, Alasdair J. Nisbet, Craig A Watkins, Tom N Mcneilly, John F. HuntleyAbstract:Background: Sheep scab, caused by infestation with the ectoparasitic mite Psoroptes Ovis, results in the rapid development of cutaneous inflammation and leads to the crusted skin lesions characteristic of the disease. We described previously the global host transcriptional response to infestation with P. Ovis, elucidating elements of the inflammatory processes which lead to the development of a rapid and profound immune response. However, the mechanisms by which this response is instigated remain unclear. To identify novel methods of intervention a better understanding of the early events involved in triggering the immune response is essential. The objective of this study was to gain a clearer understanding of the mechanisms and signaling pathways involved in the instigation of the immediate pro-inflammatory response. Results: Through a combination of transcription factor binding site enrichment and pathway analysis we identified key roles for a number of transcription factors in the instigation of cutaneous inflammation. In particular, defined roles were elucidated for the transcription factors NF-kB and AP-1 in the orchestration of the early pro-inflammatory response, with these factors being implicated in the activation of a suite of inflammatory mediators. Conclusions: Interrogation of the host temporal response to P. Ovis infestation has enabled the further identification of the mechanisms underlying the development of the immediate host pro-inflammatory response. This response involves key regulatory roles for the transcription factors NF-kB and AP-1. Pathway analysis demonstrated that the activation of thes
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Development of a cDNA microarray for the measurement of gene expression in the sheep scab mite Psoroptes Ovis
Parasites & Vectors, 2012Co-Authors: Stewart T. G. Burgess, Alasdair J. Nisbet, Edward J. Marr, Fiona Kenyon, Craig A Watkins, Alison Downing, Carol Mcnair, John F. HuntleyAbstract:Background Sheep scab is caused by the ectoparasitic mite Psoroptes Ovis which initiates a profound cutaneous inflammatory response, leading to the development of the skin lesions which are characteristic of the disease. Existing control strategies rely upon injectable endectocides and acaricidal dips but concerns over residues, eco-toxicity and the development of acaricide resistance limit the sustainability of this approach. In order to identify alternative means of disease control, a deeper understanding of both the parasite and its interaction with the host are required. Methods Herein we describe the development and utilisation of an annotated P. Ovis cDNA microarray containing 3,456 elements for the measurement of gene expression in this economically important ectoparasite. The array consists of 981 P. Ovis EST sequences printed in triplicate along with 513 control elements. Array performance was validated through the analysis of gene expression differences between fed and starved P. Ovis mites. Results Sequences represented on the array include homologues of major house dust mite allergens and tick salivary proteins, along with factors potentially involved in mite reproduction and xenobiotic metabolism. In order to validate the performance of this unique resource under biological conditions we used the array to analyse gene expression differences between fed and starved P. Ovis mites. These analyses identified a number of house dust mite allergen homologues up-regulated in fed mites and P. Ovis transcripts involved in stress responses, autophagy and chemosensory perception up-regulated in starved mites. Conclusion The P. Ovis cDNA microarray described here has been shown to be both robust and reproducible and will enable future studies to analyse gene expression in this important ectoparasite.
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the use of a Psoroptes Ovis serodiagnostic test for the analysis of a natural outbreak of sheep scab
Parasites & Vectors, 2012Co-Authors: Stewart T. G. Burgess, Alasdair J. Nisbet, Fiona Kenyon, David Frew, Francesca Nunn, G T Innocent, J F HuntleyAbstract:Background Sheep scab is a highly contagious disease of sheep caused by the ectoparasitic mite Psoroptes Ovis. The disease is endemic in the UK and has significant economic impact through its effects on performance and welfare. Diagnosis of sheep scab is achieved through observation of clinical signs e.g. itching, pruritis and wool loss and ultimately through the detection of mites in skin scrapings. Early stages of infestation are often difficult to diagnose and sub-clinical animals can be a major factor in disease spread. The development of a diagnostic assay would enable farmers and veterinarians to detect disease at an early stage, reducing the risk of developing clinical disease and limiting spread.
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The use of a Psoroptes Ovis serodiagnostic test for the analysis of a natural outbreak of sheep scab
Parasites & Vectors, 2012Co-Authors: Stewart T. G. Burgess, Alasdair J. Nisbet, Fiona Kenyon, David Frew, Francesca Nunn, G T Innocent, John F. HuntleyAbstract:Background Sheep scab is a highly contagious disease of sheep caused by the ectoparasitic mite Psoroptes Ovis . The disease is endemic in the UK and has significant economic impact through its effects on performance and welfare. Diagnosis of sheep scab is achieved through observation of clinical signs e.g. itching, pruritis and wool loss and ultimately through the detection of mites in skin scrapings. Early stages of infestation are often difficult to diagnose and sub-clinical animals can be a major factor in disease spread. The development of a diagnostic assay would enable farmers and veterinarians to detect disease at an early stage, reducing the risk of developing clinical disease and limiting spread. Methods Serum samples were obtained from an outbreak of sheep scab within an experimental flock (n = 480 (3 samples each from 160 sheep)) allowing the assessment, by ELISA of sheep scab specific antibody prior to infestation, mid-outbreak (combined with clinical assessment) and post-treatment. Results Analysis of pre-infestation samples demonstrated low levels of potential false positives (3.8%). Of the 27 animals with clinical or behavioural signs of disease 25 tested positive at the mid-outbreak sampling period, however, the remaining 2 sheep tested positive at the subsequent sampling period. Clinical assessment revealed the absence of clinical or behavioural signs of disease in 132 sheep, whilst analysis of mid-outbreak samples showed that 105 of these clinically negative animals were serologically positive, representing potential sub-clinical infestations. Conclusions This study demonstrates that this ELISA test can effectively diagnose sheep scab in a natural outbreak of disease, and more importantly, highlights its ability to detect sub-clinically infested animals. This ELISA, employing a single recombinant antigen, represents a major step forward in the diagnosis of sheep scab and may prove to be critical in any future control program.
Stijn Casaert - One of the best experts on this subject based on the ideXlab platform.
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Dermal immune responses against Psoroptes Ovis in two cattle breeds and effects of anti-inflammatory dexamethasone treatment on the development of psoroptic mange
Veterinary Research, 2021Co-Authors: Zhenzhen Chen, Edwin Claerebout, Koen Chiers, Mathilde Pas, Bart Pardon, Wouter Mol, Stijn Casaert, Nathalie Wilde, Luc Duchateau, Peter GeldhofAbstract:Psoroptic mange is a common disease of livestock, caused by Psoroptes Ovis . Compared to Holstein–Friesian (HF) cattle, the Belgian Blue (BB) cattle breed is highly susceptible to the infestation. However, the mechanism for this difference is still unclear. To determine the factors responsible for this breed susceptibility, the immune response to P. Ovis was studied in experimentally infested BB and HF cattle, using clinical signs, histology, immunohistochemical profiling and gene expression analysis of skin biopsies. The mite numbers and lesion area of BB cattle were greater than in HF during the whole study period. Significant influxes of eosinophils in the epidermis and dermis were detected in comparison with the pre-infestation samples in both breeds, with significantly higher eosinophils in BB at 6 weeks post infestation (wpi). Mast cell numbers were unaffected at all stages of infestation in HF, but were significantly elevated relative to pre-infestation in BB cattle at 2 and 6 wpi. The more pronounced cutaneous eosinophilia and higher IL-4 levels at 6 wpi in BB cattle suggest that a Th2-type immune response is underlying the higher susceptibility of the BB breed. In naturally infested BB cattle, development of the psoroptic mange lesions and eosinophils and CD3+ T cell areas were severely depressed after anti-inflammatory treatment with dexamethasone. Together, these results suggest that a stronger Th2-type immune response to P. Ovis causes the skin lesions in psoroptic mange in BB cattle and that local anti-inflammatory treatment could potentially be an alternative to control the pathology caused by this parasite.
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new insights into the use of a mite count reduction test for the detection of therapeutic acaricide efficacy in Psoroptes Ovis in cattle
International Journal for Parasitology-Drugs and Drug Resistance, 2020Co-Authors: Wouter Van Mol, Edwin Claerebout, Stijn Casaert, Peter Geldhof, B LeveckeAbstract:When used for the evaluation of drug efficacy against Psoroptes Ovis, the diagnostic performance of different sampling strategies for a mite count reduction test (MCRT) remains unclear. In the present study, a novel simulation framework was constructed that accounted for relevant biological features of P. Ovis infestations in cattle and that was parameterized with field data from 16 farms (154 animals). Second, this framework was applied to explore the impact of study specific factors (number of animals, number of sampled lesions, and number of scrapings per lesion) and biological factors (mite infestation intensity and size of lesions) on the diagnostic performance of MCRT. Its outcome provided a basis to determine the diagnostic performance of MCRT when it was applied according to the World Association for the Advancement in Veterinary Parasitology (WAAVP) and the European Medicine Agency (EMA) guidelines, and to formulate recommendations to ensure a good diagnostic performance of the MCRT. For both guidelines, the MCRT allowed to correctly detect (power 80%) reduced and normal efficacy when the therapeutic efficacy was <70%, and ≥95%, respectively. The results highlighted a reliable diagnostic performance of the MCRT when performed as recommended by WAAVP and EMA for the detection of normal drug efficacy. When used for the detection of reduced efficacy, therapeutic efficacies between 70% and 90% could not be detected with sufficient reliability. The diagnostic performance can be improved by increasing the total number of skin scrapings (increasing the number of animals, number of sampled lesions and/or number of samples per lesion). In order to help researchers and veterinarians to optimize the design of the MCRT to their field settings, the findings were translated into a simple tool.
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Resistance against macrocyclic lactones in Psoroptes Ovis in cattle
Parasites & Vectors, 2020Co-Authors: Wouter Van Mol, Zhenzhen Chen, Stijn Casaert, Nathalie Wilde, Luc Duchateau, Marieke Vanhecke, Edwin ClaereboutAbstract:Background Psoroptic mange is an important disease in Belgian Blue cattle. Treatment failure of macrocyclic lactones against Psoroptes Ovis has been reported, but clear evidence of in vivo resistance is lacking. This study assessed the efficacy of macrocyclic lactone products on 16 beef farms in Belgium and the Netherlands in vivo and in vitro . Methods On each farm a group of animals ( n = 7–14) with psoroptic mange was treated with two subcutaneous injections of a macrocyclic lactone product with 7–10 days interval (15 farms) or a single injection with a long-acting macrocyclic lactone (1 farm). In vivo efficacy was assessed by the reduction in mite counts, clinical index (proportion of the body surface affected by lesions), the proportion of the animals with negative mite counts after the first treatment round and the number of treatment rounds needed to obtain zero mites counts in all animals. A mite population was categorized as sensitive when the mite count reduction after the first treatment round > 95% and the lower limit of the uncertainty interval > 90%. Resistance was detected when both parameters were below their threshold and suspected when one parameter was too low. In vitro knockdown and mortality were evaluated in a contact test. Results The proportion of the animals with negative mite counts after the first treatment round varied from 0 to 80%. All farms needed two or more treatments rounds to obtain zero mite counts on all animals. Clinical index only started to reduce after the second treatment round. Mite populations from three farms were categorized as sensitive, one as suspected resistant and 12 as resistant. No correlation was found between in vitro lethal dose 50 and knockdown dose 50 values and in vivo efficacy parameters. Conclusions Unambiguous treatment failure was detected on 12 out of 16 farms, confirming the presence of macrocyclic lactone resistance on Belgian Blue beef farms. In vitro parameters could not discriminate the farms based on their in vivo sensitivity. The mean reduction in mite counts and the lower limit of the confidence interval are proposed as parameters to identify acaricide resistance.
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Resistance against macrocyclic lactones in Psoroptes Ovis in cattle
Parasites & vectors, 2020Co-Authors: Wouter Van Mol, Zhenzhen Chen, Stijn Casaert, Nathalie Wilde, Luc Duchateau, Marieke Vanhecke, Edwin ClaereboutAbstract:Psoroptic mange is an important disease in Belgian Blue cattle. Treatment failure of macrocyclic lactones against Psoroptes Ovis has been reported, but clear evidence of in vivo resistance is lacking. This study assessed the efficacy of macrocyclic lactone products on 16 beef farms in Belgium and the Netherlands in vivo and in vitro. On each farm a group of animals (n = 7–14) with psoroptic mange was treated with two subcutaneous injections of a macrocyclic lactone product with 7–10 days interval (15 farms) or a single injection with a long-acting macrocyclic lactone (1 farm). In vivo efficacy was assessed by the reduction in mite counts, clinical index (proportion of the body surface affected by lesions), the proportion of the animals with negative mite counts after the first treatment round and the number of treatment rounds needed to obtain zero mites counts in all animals. A mite population was categorized as sensitive when the mite count reduction after the first treatment round > 95% and the lower limit of the uncertainty interval > 90%. Resistance was detected when both parameters were below their threshold and suspected when one parameter was too low. In vitro knockdown and mortality were evaluated in a contact test. The proportion of the animals with negative mite counts after the first treatment round varied from 0 to 80%. All farms needed two or more treatments rounds to obtain zero mite counts on all animals. Clinical index only started to reduce after the second treatment round. Mite populations from three farms were categorized as sensitive, one as suspected resistant and 12 as resistant. No correlation was found between in vitro lethal dose 50 and knockdown dose 50 values and in vivo efficacy parameters. Unambiguous treatment failure was detected on 12 out of 16 farms, confirming the presence of macrocyclic lactone resistance on Belgian Blue beef farms. In vitro parameters could not discriminate the farms based on their in vivo sensitivity. The mean reduction in mite counts and the lower limit of the confidence interval are proposed as parameters to identify acaricide resistance.
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evaluatie van twee intensieve behandelingsschema s tegen Psoroptes Ovis schurft bij belgisch witblauwe runderen op negen vlaamse rundveebedrijven
Vlaams Diergeneeskundig Tijdschrift, 2015Co-Authors: Charlotte Sarre, Stijn Casaert, Thomas Geurden, Jozef Vercruysse, N De Wilde, Edwin ClaereboutAbstract:Schurft veroorzaakt door Psoroptes Ovis komt voor op de meeste Vlaamse bedrijven met Belgisch witblauw vleesvee. In deze studie werden twee intensieve behandelingsschema’s geevalueerd op negen Vlaamse vleesveebedrijven met een persisterend schurftprobleem. Op bedrijf 1 tot en met 7 werden alle dieren tweemaal behandeld (met een interval van zeven a tien dagen) met een injecteerbaar macrocyclisch lacton (ML). Op de twee laatste bedrijven werd een eenmalige injectie gegeven met de ‘long acting’-formulatie (LA) van moxidectine (10%). Na behandeling werden huidafkrabsels genomen en bij de aanwezigheid van levende mijten bij ten minste een dier werden alle dieren (bedrijven 1 tot en met 7) of enkel de positieve dieren (bedrijf 8 en 9) verder behandeld met een injecteerbaar ML. Op alle bedrijven waren de dieren klinisch genezen en schijnbaar vrij van mijten na twee tot negen behandelingsrondes (twee injecties met zeven a tien dagen interval of een LA-injectie). Hoewel er op de eerste zeven bedrijven na het daaropvolgende weideseizoen opnieuw tekenen van schurft te zien waren, was dit in mindere mate en de schurft was gemakkelijker onder controle te houden.
Stewart T. G. Burgess - One of the best experts on this subject based on the ideXlab platform.
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Psoroptes Ovis early immunoreactive protein pso eip 1 a novel diagnostic antigen for sheep scab
Parasite Immunology, 2020Co-Authors: Stewart T. G. Burgess, David Frew, Francesca Nunn, Kevin Mclean, Kath Bartley, Neil F Inglis, Kara D Mcgeachy, Michael Taliansky, Andrew J LoveAbstract:Aims Serodiagnosis of sheep scab is an established diagnostic method and has become popular in recent years. However, the current diagnostic antigen, Pso o 2, has shown promise as a component of a recombinant vaccine for scab, making it incompatible with discriminating between infected and vaccinated animals (DIVA). Here, we describe the discovery and characterization of a novel Psoroptes Ovis immunodiagnostic antigen, P. Ovis-Early Immunoreactive Protein-1 (Pso-EIP-1). Methods and results Pso-EIP-1 is a highly abundant member of a six-gene family with no known homologs, indicating its potential uniqueness to P. Ovis. Expression of recombinant Pso-EIP-1 (rPso-EIP-1) required a C-terminal fusion protein for stability and specific IgG immunoreactivity against rPso-EIP-1 was observed in sheep serum from 1 to 2 weeks post-infestation, indicating its highly immunogenic nature. Two of the three in silico-predicted B-cell epitopes of Pso-EIP-1 were confirmed by in vitro epitope mapping and, in a direct comparison by ELISA, Pso-EIP-1 performed to the same levels as Pso o 2 in terms of sensitivity, specificity and ability to diagnose P. Ovis on sheep within 2 weeks of infestation. Conclusion Pso-EIP-1 represents a novel diagnostic antigen for sheep scab with comparable levels of sensitivity and specificity to the existing Pso o 2 antigen.
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a genomic analysis and transcriptomic atlas of gene expression in Psoroptes Ovis reveals feeding and stage specific patterns of allergen expression
BMC Genomics, 2019Co-Authors: Stewart T. G. Burgess, Stephane Rombauts, Kathryn Bartley, Edward J. Marr, Robert J. Weaver, Jessica C. Prickett, Francesca Nunn, Rachel E. Down, Jackie Dunn, Thomas Van LeeuwenAbstract:Psoroptic mange, caused by infestation with the ectoparasitic mite, Psoroptes Ovis, is highly contagious, resulting in intense pruritus and represents a major welfare and economic concern for the livestock industry Worldwide. Control relies on injectable endectocides and organophosphate dips, but concerns over residues, environmental contamination, and the development of resistance threaten the sustainability of this approach, highlighting interest in alternative control methods. However, development of vaccines and identification of chemotherapeutic targets is hampered by the lack of P. Ovis transcriptomic and genomic resources. Building on the recent publication of the P. Ovis draft genome, here we present a genomic analysis and transcriptomic atlas of gene expression in P. Ovis revealing feeding- and stage-specific patterns of gene expression, including novel multigene families and allergens. Network-based clustering revealed 14 gene clusters demonstrating either single- or multi-stage specific gene expression patterns, with 3075 female-specific, 890 male-specific and 112, 217 and 526 transcripts showing larval, protonymph and tritonymph specific-expression, respectively. Detailed analysis of P. Ovis allergens revealed stage-specific patterns of allergen gene expression, many of which were also enriched in “fed” mites and tritonymphs, highlighting an important feeding-related allergenicity in this developmental stage. Pair-wise analysis of differential expression between life-cycle stages identified patterns of sex-biased gene expression and also identified novel P. Ovis multigene families including known allergens and novel genes with high levels of stage-specific expression. The genomic and transcriptomic atlas described here represents a unique resource for the acarid-research community, whilst the OrcAE platform makes this freely available, facilitating further community-led curation of the draft P. Ovis genome.
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A genomic analysis and transcriptomic atlas of gene expression in Psoroptes Ovis reveals feeding- and stage-specific patterns of allergen expression
BMC Genomics, 2019Co-Authors: Stewart T. G. Burgess, Stephane Rombauts, Kathryn Bartley, Edward J. Marr, Robert J. Weaver, Jessica C. Prickett, Francesca G. Nunn, Rachel E. Down, Jackie Dunn, Thomas LeeuwenAbstract:Background Psoroptic mange, caused by infestation with the ectoparasitic mite, Psoroptes Ovis , is highly contagious, resulting in intense pruritus and represents a major welfare and economic concern for the livestock industry Worldwide. Control relies on injectable endectocides and organophosphate dips, but concerns over residues, environmental contamination, and the development of resistance threaten the sustainability of this approach, highlighting interest in alternative control methods. However, development of vaccines and identification of chemotherapeutic targets is hampered by the lack of P. Ovis transcriptomic and genomic resources. Results Building on the recent publication of the P. Ovis draft genome, here we present a genomic analysis and transcriptomic atlas of gene expression in P. Ovis revealing feeding- and stage-specific patterns of gene expression, including novel multigene families and allergens. Network-based clustering revealed 14 gene clusters demonstrating either single- or multi-stage specific gene expression patterns, with 3075 female-specific, 890 male-specific and 112, 217 and 526 transcripts showing larval, protonymph and tritonymph specific-expression, respectively. Detailed analysis of P. Ovis allergens revealed stage-specific patterns of allergen gene expression, many of which were also enriched in “fed” mites and tritonymphs, highlighting an important feeding-related allergenicity in this developmental stage. Pair-wise analysis of differential expression between life-cycle stages identified patterns of sex-biased gene expression and also identified novel P. Ovis multigene families including known allergens and novel genes with high levels of stage-specific expression. Conclusions The genomic and transcriptomic atlas described here represents a unique resource for the acarid-research community, whilst the OrcAE platform makes this freely available, facilitating further community-led curation of the draft P. Ovis genome.
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performance of the Psoroptes Ovis antibody enzyme linked immunosorbent assay in the face of low level mite infestation
Veterinary Record, 2019Co-Authors: Kim Hamer, Stewart T. G. Burgess, Valentina Busin, Neil SargisonAbstract:Psoroptes Ovis mites, the causative agent of sheep scab, can severely compromise sheep welfare and production. However, in subclinical infections, mite detection is difficult increasing the risk of spread. A recent serodiagnostic test, based on detecting host antibodies to the P Ovis allergen, Pso o 2, has made the detection of subclinical infection possible. The use of this test was demonstrated in subclinical situations, through an opportunistic observational study on an extensive hill farm and a lowland flock with recently introduced, quarantined livestock. Twelve animals were tested from each group. Breeding ewes and lambs on the hill farm had seroprevalences of 16 per cent (12.5–17.8 per cent) and 8.3 per cent (4.8–10.1 per cent), respectively. Quarantined store lambs had a seroprevalence of 16.7 per cent (13.2–18.5 per cent); no evidence of P Ovis was found in quarantined replacement ewes. By detecting subclinical infection, this serological test could be a powerful tool in sheep scab control, for quarantine procedures, accreditation programmes, and possibly regional or national eradication protocols.
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Gene silencing by RNA interference in the ectoparasitic mite, Psoroptes Ovis
Veterinary Research, 2018Co-Authors: Edward J. Marr, Harry W. Wright, Alasdair J. Nisbet, Neil D. Sargison, Stewart T. G. BurgessAbstract:The presence of components of the RNA interference (RNAi) pathway in Psoroptes Ovis , an ectoparasitic mite responsible for psoroptic mange, was investigated through interrogation of the P. Ovis genome. Homologues of transcripts representing critical elements for achieving effective RNAi in the mite, Tetranychus urticae and the model organisms Caenorhabditis elegans and Drosophila melanogaster were identified and, following the development of a non-invasive immersion method of double stranded RNA delivery, gene silencing by RNAi was successfully demonstrated in P. Ovis. Significant reductions in transcript levels were achieved for three target genes which encode the Group 2 allergen (Pso o 2), mu-class glutathione S -transferase ( Po GST-mu1) and beta-tubulin ( Po βtub). This is the first demonstration of RNAi in P. Ovis and provides a mechanism for mining transcriptomic and genomic datasets for novel control targets against this economically important ectoparasite.
