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Shelley F. Walton - One of the best experts on this subject based on the ideXlab platform.
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characterization of sarcoptes scabiei tropomyosin and paramyosin immunoreactive allergens in Scabies
American Journal of Tropical Medicine and Hygiene, 2017Co-Authors: Marion Desclozeaux, Kate E. Mounsey, Farhana Riaz Chaudhry, Shelley F. WaltonAbstract:Abstract. Scabies is a human skin disease due to the burrowing ectoparasite Sarcoptes scabiei var. hominis resulting in intense itching and inflammation and manifesting as a skin allergy. Because of insufficient mite material and lack of in vitro propagation system for antigen preparation, Scabies is a challenging disease to develop serological diagnostics. For allergen characterization, full-length S. scabiei tropomyosin (Sar s 10) was cloned, expressed in pET-15b, and assessed for reactivity with IgE antibodies from human sera. IgE binding was observed to Sar s 10 with sera collected from subjects with ordinary Scabies, house dust mite (HDM)-positive and naive subjects and a diagnostic sensitivity of < 30% was observed. S. scabiei paramyosin (Sar s 11) was cloned, and expressed in pET-28a in three overlapping fragments designated Sspara1, Sspara2, and Sspara3. IgE and IgG binding was observed to Sspara2 and Sspara3 antigens with sera collected from ordinary Scabies, and HDM-positive subjects, but no binding was observed with sera collected from naive subjects. Sspara2 displayed excellent diagnostic potential with 98% sensitivity and 90% specificity observed for IgE binding and 70% sensitivity for IgG. In contrast, the diagnostic sensitivity of Sspara3 was 84% for IgE binding and 40% for IgG binding. In combination, Sspara2 and Sspara3 provided an IgE sensitivity of 94%. This study shows that IgE binding to Sspara2 and Sspara3 is a highly sensitive method for diagnosis of Scabies infestation in clinical practice. The developed enzyme-linked immunosorbent assay helps direct future development of a specific diagnostic tool for Scabies.
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Host immune responses to the itch mite, Sarcoptes scabiei, in humans.
Parasites & vectors, 2017Co-Authors: Sajad A. Bhat, Kate E. Mounsey, Xiaosong Liu, Shelley F. WaltonAbstract:Scabies is a parasitic disease due to infestation of skin by the burrowing mite Sarcoptes scabiei. Scabies is a major public health problem and endemic in resource poor communities worldwide affecting over 100 million people. Associated bacterial infections cause substantial morbidity, and in severe cases can lead to renal and cardiac diseases. Mite infestation of the skin causes localised cutaneous inflammation, pruritus, skin lesions, and allergic and inflammatory responses are mounted by the host against the mite and its products. Our current understanding of the immune and inflammatory responses associated with the clinical manifestations in Scabies is far outweighed by the significant global impact of the disease. This review aims to provide a better understanding of human immune responses to S. scabiei in ordinary and crusted Scabies phenotypes.
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prospective study in a porcine model of sarcoptes scabiei indicates the association of th2 and th17 pathways with the clinical severity of Scabies
PLOS Neglected Tropical Diseases, 2015Co-Authors: Kate E. Mounsey, Bart J. Currie, Shelley F. Walton, Deborah C. Holt, Cielo Pasay, Hugh C Murray, Helle Bielefeldtohmann, James S. MccarthyAbstract:Understanding of Scabies immunopathology has been hampered by the inability to undertake longitudinal studies in humans. Pigs are a useful animal model for Scabies, and show clinical and immunologic changes similar to those in humans. Crusted Scabies can be readily established in pigs by treatment with the glucocorticoid dexamethasone (Dex).Prospective study of 24 pigs in four groups: a) Scabies+/Dex+, b) Scabies+/Dex-, c) Scabies-/Dex+ and d) Scabies-/Dex-. Clinical symptoms were monitored. Histological profiling and transcriptional analysis of skin biopsies was undertaken to compare changes in cell infiltrates and representative cytokines. A range of clinical responses to Sarcoptes scabiei were observed in Dex treated and non-immunosuppressed pigs. An association was confirmed between disease severity and transcription of the Th2 cytokines IL-4 and IL-13, and up-regulation of the Th17 cytokines IL-17 and IL-23 in pigs with crusted Scabies. Immunohistochemistry revealed marked infiltration of lymphocytes and mast cells, and strong staining for IL-17.While an allergic Th2 type response to Scabies has been previously described, these results suggest that IL-17 related pathways may also contribute to immunopathology of crusted Scabies. This may lead to new strategies to protect vulnerable subjects from contracting recurrent crusted Scabies.
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crusted Scabies is associated with increased il 17 secretion by skin t cells
Parasite Immunology, 2014Co-Authors: Xiaosong Liu, Bart J. Currie, Shelley F. Walton, James S. Mccarthy, Deborah C. Holt, Andrew Kelly, Hugh C Murray, Mallory KingAbstract:Scabies is an ectoparasitic infestation by the mite Sarcoptes scabiei. Although commonly self-limiting, a fraction of patients develop severely debilitating crusted Scabies. The immune mechanisms underlying the development of crusted Scabies are unclear, and undertaking longitudinal infection studies in humans is difficult. We utilized a porcine model to compare cellular immune responses in peripheral blood and skin of pigs with different clinical manifestations of Scabies (n = 12), and in uninfected controls (n = 6). Although clinical symptoms were not evident until at least 4 weeks post-infestation, the numbers of peripheral IFNγ-secreting CD4+ T cells and γδ T cells increased in infected pigs from week 1 post-infestation. γδ T cells remained increased in the blood at week 15 post-infestation. At week 15, skin cell infiltrates from pigs with crusted Scabies had significantly higher CD8+ T cell, γδ T cell and IL-17+ cell numbers than those with ordinary Scabies. Peripheral IL-17 levels were not increased, suggesting that localized skin IL-17-secreting T cells may play a critical role in the pathogenesis of crusted Scabies development. Given the potential of anti-IL-17 immunotherapy demonstrated for other inflammatory skin diseases, this study may provide a novel therapeutic avenue for patients with recurrent crusted Scabies.
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CDNA LIBRARY FROM SARCOPTES SCABIEI VAR. HOMINIS AND EVALUATION OF ITS VACCINE POTENTIAL IN A RABBIT/S. SCABIEI VAR. CANIS MODEL
2013Co-Authors: Pearly Harumal, Bart J. Currie, Larry G. Arlian, Shelley F. Walton, Deborah C. Holt, Marjorie Morgan, Jurgen Rode, J. KempAbstract:Abstract. Sarcoptes scabiei (“itchmite”) causes Scabies, a disease of considerable human and veterinary significance. Little work has been done at the molecular level because of the difficulty of obtaining mites. We have used mites in skin from the bedding of crusted Scabies patients for the construction of a library of 10 5 cDNAs from S. scabiei var. hominis cloned in the vector pGEX4T-2. We describe the isolation by immunoscreening of 2 clones, one of which (Ssag1) is homologous to and cross-reactive with the house dust mite Euroglyphus maynei allergen M-177, an apolipoprotein from hemolymph. Immunohistochemistry revealed that it is located around the internal organs and cuticle of the mite and in eggs. Although it was not found to be protective in a challenge trial, the rabbits did not exhibit typical crust characteristics. This work shows that it is now possible to conduct such challenge trials withcloned Scabies antigens
Bart J. Currie - One of the best experts on this subject based on the ideXlab platform.
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mitochondrial genome sequence of the Scabies mite provides insight into the genetic diversity of individual Scabies infections
PLOS Neglected Tropical Diseases, 2016Co-Authors: Bart J. Currie, Deborah C. Holt, Katja Fischer, Ehtesham Mofiz, Torsten Seemann, Melanie Bahlo, Anthony T PapenfussAbstract:The Scabies mite, Sarcoptes scabiei, is an obligate parasite of the skin that infects humans and other animal species, causing Scabies, a contagious disease characterized by extreme itching. Scabies infections are a major health problem, particularly in remote Indigenous communities in Australia, where co-infection of epidermal Scabies lesions by Group A Streptococci or Staphylococcus aureus is thought to be responsible for the high rate of rheumatic heart disease and chronic kidney disease. We collected and separately sequenced mite DNA from several pools of thousands of whole mites from a porcine model of Scabies (S. scabiei var. suis) and two human patients (S. scabiei var. hominis) living in different regions of northern Australia. Our sequencing samples the mite and its metagenome, including the mite gut flora and the wound micro-environment. Here, we describe the mitochondrial genome of the Scabies mite. We developed a new de novo assembly pipeline based on a bait-and-reassemble strategy, which produced a 14 kilobase mitochondrial genome sequence assembly. We also annotated 35 genes and have compared these to other Acari mites. We identified single nucleotide polymorphisms (SNPs) and used these to infer the presence of six haplogroups in our samples, Remarkably, these fall into two closely-related clades with one clade including both human and pig varieties. This supports earlier findings that only limited genetic differences may separate some human and animal varieties, and raises the possibility of cross-host infections. Finally, we used these mitochondrial haplotypes to show that the genetic diversity of individual infections is typically small with 1–3 distinct haplotypes per infestation.
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prospective study in a porcine model of sarcoptes scabiei indicates the association of th2 and th17 pathways with the clinical severity of Scabies
PLOS Neglected Tropical Diseases, 2015Co-Authors: Kate E. Mounsey, Bart J. Currie, Shelley F. Walton, Deborah C. Holt, Cielo Pasay, Hugh C Murray, Helle Bielefeldtohmann, James S. MccarthyAbstract:Understanding of Scabies immunopathology has been hampered by the inability to undertake longitudinal studies in humans. Pigs are a useful animal model for Scabies, and show clinical and immunologic changes similar to those in humans. Crusted Scabies can be readily established in pigs by treatment with the glucocorticoid dexamethasone (Dex).Prospective study of 24 pigs in four groups: a) Scabies+/Dex+, b) Scabies+/Dex-, c) Scabies-/Dex+ and d) Scabies-/Dex-. Clinical symptoms were monitored. Histological profiling and transcriptional analysis of skin biopsies was undertaken to compare changes in cell infiltrates and representative cytokines. A range of clinical responses to Sarcoptes scabiei were observed in Dex treated and non-immunosuppressed pigs. An association was confirmed between disease severity and transcription of the Th2 cytokines IL-4 and IL-13, and up-regulation of the Th17 cytokines IL-17 and IL-23 in pigs with crusted Scabies. Immunohistochemistry revealed marked infiltration of lymphocytes and mast cells, and strong staining for IL-17.While an allergic Th2 type response to Scabies has been previously described, these results suggest that IL-17 related pathways may also contribute to immunopathology of crusted Scabies. This may lead to new strategies to protect vulnerable subjects from contracting recurrent crusted Scabies.
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crusted Scabies is associated with increased il 17 secretion by skin t cells
Parasite Immunology, 2014Co-Authors: Xiaosong Liu, Bart J. Currie, Shelley F. Walton, James S. Mccarthy, Deborah C. Holt, Andrew Kelly, Hugh C Murray, Mallory KingAbstract:Scabies is an ectoparasitic infestation by the mite Sarcoptes scabiei. Although commonly self-limiting, a fraction of patients develop severely debilitating crusted Scabies. The immune mechanisms underlying the development of crusted Scabies are unclear, and undertaking longitudinal infection studies in humans is difficult. We utilized a porcine model to compare cellular immune responses in peripheral blood and skin of pigs with different clinical manifestations of Scabies (n = 12), and in uninfected controls (n = 6). Although clinical symptoms were not evident until at least 4 weeks post-infestation, the numbers of peripheral IFNγ-secreting CD4+ T cells and γδ T cells increased in infected pigs from week 1 post-infestation. γδ T cells remained increased in the blood at week 15 post-infestation. At week 15, skin cell infiltrates from pigs with crusted Scabies had significantly higher CD8+ T cell, γδ T cell and IL-17+ cell numbers than those with ordinary Scabies. Peripheral IL-17 levels were not increased, suggesting that localized skin IL-17-secreting T cells may play a critical role in the pathogenesis of crusted Scabies development. Given the potential of anti-IL-17 immunotherapy demonstrated for other inflammatory skin diseases, this study may provide a novel therapeutic avenue for patients with recurrent crusted Scabies.
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CDNA LIBRARY FROM SARCOPTES SCABIEI VAR. HOMINIS AND EVALUATION OF ITS VACCINE POTENTIAL IN A RABBIT/S. SCABIEI VAR. CANIS MODEL
2013Co-Authors: Pearly Harumal, Bart J. Currie, Larry G. Arlian, Shelley F. Walton, Deborah C. Holt, Marjorie Morgan, Jurgen Rode, J. KempAbstract:Abstract. Sarcoptes scabiei (“itchmite”) causes Scabies, a disease of considerable human and veterinary significance. Little work has been done at the molecular level because of the difficulty of obtaining mites. We have used mites in skin from the bedding of crusted Scabies patients for the construction of a library of 10 5 cDNAs from S. scabiei var. hominis cloned in the vector pGEX4T-2. We describe the isolation by immunoscreening of 2 clones, one of which (Ssag1) is homologous to and cross-reactive with the house dust mite Euroglyphus maynei allergen M-177, an apolipoprotein from hemolymph. Immunohistochemistry revealed that it is located around the internal organs and cuticle of the mite and in eggs. Although it was not found to be protective in a challenge trial, the rabbits did not exhibit typical crust characteristics. This work shows that it is now possible to conduct such challenge trials withcloned Scabies antigens
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antibody responses to sarcoptes scabiei apolipoprotein in a porcine model relevance to immunodiagnosis of recent infection
PLOS ONE, 2013Co-Authors: Bart J. Currie, Shelley F. Walton, James S. Mccarthy, Deborah C. Holt, Cielo Pasay, Melanie Rampton, Andrew Kelly, Kate E. MounseyAbstract:No commercial immunodiagnostic tests for human Scabies are currently available, and existing animal tests are not sufficiently sensitive. The recombinant Sarcoptes scabiei apolipoprotein antigen Sar s 14.3 is a promising immunodiagnostic, eliciting high levels of IgE and IgG in infected people. Limited data are available regarding the temporal development of antibodies to Sar s 14.3, an issue of relevance in terms of immunodiagnosis. We utilised a porcine model to prospectively compare specific antibody responses to a primary infestation by ELISA, to Sar s 14.3 and to S. scabiei whole mite antigen extract (WMA). Differences in the antibody profile between antigens were apparent, with Sar s 14.3 responses detected earlier, and declining significantly after peak infestation compared to WMA. Both antigens resulted in >90% diagnostic sensitivity from weeks 8–16 post infestation. These data provide important information on the temporal development of humoral immune responses in Scabies and further supports the development of recombinant antigen based immunodiagnostic tests for recent Scabies infestations.
David J. Kemp - One of the best experts on this subject based on the ideXlab platform.
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increased allergic immune response to sarcoptes scabiei antigens in crusted versus ordinary Scabies
Clinical and Vaccine Immunology, 2010Co-Authors: Shelley F. Walton, Bart J. Currie, Deborah C. Holt, David J. Kemp, Susan J Pizzutto, Amy Slender, Linda T Viberg, Belinda J Hales, Jennifer M RollandAbstract:Scabies, a parasitic skin infestation by the burrowing “itch” mite Sarcoptes scabiei, causes significant health problems for children and adults worldwide. Crusted Scabies is a particularly severe form of Scabies in which mites multiply into the millions, causing extensive skin crusting. The symptoms and signs of Scabies suggest host immunity to the Scabies mite, but the specific resistant response in humans remains largely uncharacterized. We used 4 Scabies mite recombinant proteins with sequence homology to extensively studied house dust mite allergens to investigate a differential immune response between ordinary Scabies and the debilitating crusted form of the disease. Subjects with either disease form showed serum IgE against recombinant S. scabiei cysteine and serine proteases and apolipoprotein, whereas naive subjects showed minimal IgE reactivity. Significantly (P
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increased allergic immune response to sarcoptes scabiei antigens in crusted versus ordinary Scabies
Clinical and Vaccine Immunology, 2010Co-Authors: Shelley F. Walton, Bart J. Currie, Deborah C. Holt, David J. Kemp, Susan J Pizzutto, Amy Slender, Linda T Viberg, Belinda J Hales, Jennifer M RollandAbstract:Scabies is a disease of the skin caused by the burrowing “itch” mite Sarcoptes scabiei. The predominant disease manifestations are mediated through inflammatory and allergic-like reactions to mite products, leading to intensely pruritic skin lesions. A spectrum of disease is recognized, from the more common ordinary Scabies (OS), with an average infestation of 10 to 15 mites per person, to a rare and severely debilitating form of the disease termed crusted (Norwegian) Scabies (CS). In this form, mite infestations can number in the millions, and hyperkeratotic skin crusts develop (41, 50). Due to the extreme burden of mites, CS is considerably more infectious, and infectivity persists far longer, as eradicating mites from heavily crusted skin is extremely difficult. Crusted Scabies is an important public health problem, not only for the individuals concerned, but also for their families and communities, in which sufferers may act as “core transmitters” who continue to reinfect others. In many remote Aboriginal communities in northern Australia, Scabies prevalence is high: up to 65% in children, with first presentation peaking at 2 months of age (13). Adult female mites reside in burrows within the stratum granulosum of the epidermis. The clinical rash and itch present as papules or vesicles that may contain individual mites, eggs, egg cases, mite fecal pellets, and debris present in the burrow. A secondary, more generalized papular immune response also occurs. The associated underlying inflammatory response varies in intensity, with combinations of lymphocytes, histiocytes, and polymorphonuclear leukocytes (10, 47). Due to difficulties in isolating sarcoptic mites on the host in OS and to the clinical symptoms imitating those of other skin diseases, Scabies is a challenging disease to diagnose (48). To date, limited investigations of humoral immunity to the Scabies mite (SM) in patients have yielded contradictory results and have used scabietic extracts from other hosts, such as dogs (37). Interpretation of these studies is complex, as Scabies mites are highly host specific and generally produce only a transient, self-limiting reaction in the nonpermissive host. In Darwin, Northern Territory, Australia, patients with CS were noted to have extremely high levels of total IgE and IgG in serum (41). Western blotting with plasma from these patients demonstrated that 6 of 7 individuals had strong IgE binding to S. scabiei var. canis protein extracts (2). Immunochemical studies have previously demonstrated that sera from rabbits infested with S. scabiei var. canis bind to house dust mite (HDM) extracts and, conversely, that sera from rabbits immunized with HDM extract bind with S. scabiei var. canis whole-mite protein extract (4-6, 18, 20, 36). Allergens from HDMs are recognized as major causes of allergic respiratory disease in humans (17, 43). As SMs and HDMs are phylogenetically related arthropods with similar nutritional requirements, it is not surprising that these mites or their excreta have homologous allergens. However, it is likely that only a few of these allergens are cross-reactive. For example, Der p 5 from the HDM Dermatophagoides pteronyssinus and Blo t 5 from the storage mite Blomia tropicalis have been studied extensively, and although they have 43% amino acid identity, they are not IgE cross-reactive (31). The identities of the specific cross-reactive molecules between S. scabiei and D. pteronyssinus remain undefined but may be glycan related (33). The recent development of S. scabiei cDNA libraries and expressed sequence tag (EST) databases (21, 29) allows more precise characterization of the specific antigens responsible for the immune reactions to the SM. The cDNAs encoding S. scabiei var. hominis cysteine proteases (27), serine proteases (26), glutathione S-transferase (GST) (16), and apolipoprotein (25) show homology to the D. pteronyssinus HDM group 1, 3, 8, and 14 allergens, respectively (43). As with HDMs, the availability of recombinant proteins and identification of key immunoreactive allergens for the SM would facilitate development of refined diagnosis and potential immunotherapy. Thus, more effective control of mite infestations at both an individual and a community level may be possible. We report here the characterization of specific antibody binding profiles and cellular immune responses of subjects with clinical Scabies by using purified S. scabiei var. hominis recombinant proteins. Quantitative IgE inhibition analysis of cross-reactivity with HDM allergens identified IgE epitopes of Scabies mite proteins distinct from HDM epitopes, a prerequisite for using purified allergens in Scabies diagnosis and therapy.
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a tractable experimental model for study of human and animal Scabies
PLOS Neglected Tropical Diseases, 2010Co-Authors: Kate E. Mounsey, James S. Mccarthy, David J. Kemp, Cielo Pasay, Andrew Kelly, Meifong Ho, Charlene Willis, Katja FischerAbstract:BACKGROUND: Scabies is a parasitic skin infestation caused by the burrowing mite Sarcoptes scabiei. It is common worldwide and spreads rapidly under crowded conditions, such as those found in socially disadvantaged communities of Indigenous populations and in developing countries. Pruritic Scabies lesions facilitate opportunistic bacterial infections, particularly Group A streptococci. Streptococcal infections cause significant sequelae and the increased community streptococcal burden has led to extreme levels of acute rheumatic fever and rheumatic heart disease in Australia's Indigenous communities. In addition, emerging resistance to currently available therapeutics emphasizes the need to identify potential targets for novel chemotherapeutic and/or immunological intervention. Scabies research has been severely limited by the availability of parasites, and Scabies remains a truly neglected infectious disease. We report development of a tractable model for Scabies in the pig, Sus domestica. METHODOLOGY/PRINCIPAL FINDINGS: Over five years and involving ten independent cohorts, we have developed a protocol for continuous passage of Sarcoptes scabiei var. suis. To increase intensity and duration of infestation without generating animal welfare issues we have optimised an immunosuppression regimen utilising daily oral treatment with 0.2 mg/kg dexamethasone. Only mild, controlled side effects are observed, and mange infection can be maintained indefinitely providing large mite numbers (> 6000 mites/g skin) for molecular-based research on Scabies. In pilot experiments we explore whether any adaptation of the mite population is reflected in genetic changes. Phylogenetic analysis was performed comparing sets of genetic data obtained from pig mites collected from naturally infected pigs with data from pig mites collected from the most recent cohort. CONCLUSIONS/SIGNIFICANCE: A reliable pig/Scabies animal model will facilitate in vivo studies on host immune responses to Scabies including the relations to the associated bacterial pathogenesis and more detailed studies of molecular evolution and host adaptation. It is a most needed tool for the further investigation of this important and widespread parasitic disease.
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Scabies mite inactivated serine protease paralogs inhibit the human complement system
Journal of Immunology, 2009Co-Authors: Frida C Bergstrom, David J. Kemp, Katja Fischer, Simone L Reynolds, Masego Johnstone, Robert N Pike, Ashley M Buckle, Anna M BlomAbstract:Infestation of skin by the parasitic itch mite Sarcoptes scabiei afflicts 300 million people worldwide and there is a need for novel and efficient therapies. We have previously identified a multigene family of serine proteases comprising multiple catalytically inactive members (Scabies mite-inactivated protease paralogs (SMIPPs)), which are secreted into the gut of S. scabiei. SMIPPs are located in the mite gut and in feces excreted into the upper epidermis. Scabies mites feed on epidermal protein, including host plasma; consequently, they are exposed to host defense mechanisms both internally and externally. We found that two recombinantly expressed SMIPPs inhibited all three pathways of the human complement system. Both SMIPPs exerted their inhibitory action due to binding of three molecules involved in the three different mechanisms which initiate complement: C1q, mannose-binding lectin, and properdin. Both SMIPPs bound to the stalk domains of C1q, possibly displacing or inhibiting C1r/C1s, which are associated with the same domain. Furthermore, we found that binding of both SMIPPs to properdin resulted in prevention of assembly of the alternative pathway convertases. However, the SMIPPs were not able to dissociate already formed convertases. Immunohistochemical staining demonstrated the presence of C1q in the gut of Scabies mites in skin burrows. We propose that SMIPPs minimize complement-mediated gut damage and thus create a favorable environment for the Scabies mites.
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Analysis of Sarcoptes scabiei finds no evidence of infection with Wolbachia.
International journal for parasitology, 2004Co-Authors: Kate E. Mounsey, Bart J. Currie, Deborah C. Holt, Krista Fischer, David J. Kemp, Shelley F. WaltonAbstract:The endosymbiont Wolbachia has been detected in a range of filarial nematodes and parasitic mites and is known to affect host reproductive compatibility and potentially evolutionary processes. PCR of Wolbachia surface protein (wsp), ftsZ and 16SrRNA genes from individual Sarcoptes scabiei mites obtained from a series of individual hosts, and database searches of an S. scabiei var. hominis EST library failed to detect Wolbachia genes. Therefore, Wolbachia appears not to be involved in the genetic subdivision observed between varieties of host-associated S. scabiei or, involved in the inflammatory disease pathogenesis of Scabies unlike its activity in filarial infection.
Deborah C. Holt - One of the best experts on this subject based on the ideXlab platform.
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mitochondrial genome sequence of the Scabies mite provides insight into the genetic diversity of individual Scabies infections
PLOS Neglected Tropical Diseases, 2016Co-Authors: Bart J. Currie, Deborah C. Holt, Katja Fischer, Ehtesham Mofiz, Torsten Seemann, Melanie Bahlo, Anthony T PapenfussAbstract:The Scabies mite, Sarcoptes scabiei, is an obligate parasite of the skin that infects humans and other animal species, causing Scabies, a contagious disease characterized by extreme itching. Scabies infections are a major health problem, particularly in remote Indigenous communities in Australia, where co-infection of epidermal Scabies lesions by Group A Streptococci or Staphylococcus aureus is thought to be responsible for the high rate of rheumatic heart disease and chronic kidney disease. We collected and separately sequenced mite DNA from several pools of thousands of whole mites from a porcine model of Scabies (S. scabiei var. suis) and two human patients (S. scabiei var. hominis) living in different regions of northern Australia. Our sequencing samples the mite and its metagenome, including the mite gut flora and the wound micro-environment. Here, we describe the mitochondrial genome of the Scabies mite. We developed a new de novo assembly pipeline based on a bait-and-reassemble strategy, which produced a 14 kilobase mitochondrial genome sequence assembly. We also annotated 35 genes and have compared these to other Acari mites. We identified single nucleotide polymorphisms (SNPs) and used these to infer the presence of six haplogroups in our samples, Remarkably, these fall into two closely-related clades with one clade including both human and pig varieties. This supports earlier findings that only limited genetic differences may separate some human and animal varieties, and raises the possibility of cross-host infections. Finally, we used these mitochondrial haplotypes to show that the genetic diversity of individual infections is typically small with 1–3 distinct haplotypes per infestation.
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prospective study in a porcine model of sarcoptes scabiei indicates the association of th2 and th17 pathways with the clinical severity of Scabies
PLOS Neglected Tropical Diseases, 2015Co-Authors: Kate E. Mounsey, Bart J. Currie, Shelley F. Walton, Deborah C. Holt, Cielo Pasay, Hugh C Murray, Helle Bielefeldtohmann, James S. MccarthyAbstract:Understanding of Scabies immunopathology has been hampered by the inability to undertake longitudinal studies in humans. Pigs are a useful animal model for Scabies, and show clinical and immunologic changes similar to those in humans. Crusted Scabies can be readily established in pigs by treatment with the glucocorticoid dexamethasone (Dex).Prospective study of 24 pigs in four groups: a) Scabies+/Dex+, b) Scabies+/Dex-, c) Scabies-/Dex+ and d) Scabies-/Dex-. Clinical symptoms were monitored. Histological profiling and transcriptional analysis of skin biopsies was undertaken to compare changes in cell infiltrates and representative cytokines. A range of clinical responses to Sarcoptes scabiei were observed in Dex treated and non-immunosuppressed pigs. An association was confirmed between disease severity and transcription of the Th2 cytokines IL-4 and IL-13, and up-regulation of the Th17 cytokines IL-17 and IL-23 in pigs with crusted Scabies. Immunohistochemistry revealed marked infiltration of lymphocytes and mast cells, and strong staining for IL-17.While an allergic Th2 type response to Scabies has been previously described, these results suggest that IL-17 related pathways may also contribute to immunopathology of crusted Scabies. This may lead to new strategies to protect vulnerable subjects from contracting recurrent crusted Scabies.
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crusted Scabies is associated with increased il 17 secretion by skin t cells
Parasite Immunology, 2014Co-Authors: Xiaosong Liu, Bart J. Currie, Shelley F. Walton, James S. Mccarthy, Deborah C. Holt, Andrew Kelly, Hugh C Murray, Mallory KingAbstract:Scabies is an ectoparasitic infestation by the mite Sarcoptes scabiei. Although commonly self-limiting, a fraction of patients develop severely debilitating crusted Scabies. The immune mechanisms underlying the development of crusted Scabies are unclear, and undertaking longitudinal infection studies in humans is difficult. We utilized a porcine model to compare cellular immune responses in peripheral blood and skin of pigs with different clinical manifestations of Scabies (n = 12), and in uninfected controls (n = 6). Although clinical symptoms were not evident until at least 4 weeks post-infestation, the numbers of peripheral IFNγ-secreting CD4+ T cells and γδ T cells increased in infected pigs from week 1 post-infestation. γδ T cells remained increased in the blood at week 15 post-infestation. At week 15, skin cell infiltrates from pigs with crusted Scabies had significantly higher CD8+ T cell, γδ T cell and IL-17+ cell numbers than those with ordinary Scabies. Peripheral IL-17 levels were not increased, suggesting that localized skin IL-17-secreting T cells may play a critical role in the pathogenesis of crusted Scabies development. Given the potential of anti-IL-17 immunotherapy demonstrated for other inflammatory skin diseases, this study may provide a novel therapeutic avenue for patients with recurrent crusted Scabies.
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CDNA LIBRARY FROM SARCOPTES SCABIEI VAR. HOMINIS AND EVALUATION OF ITS VACCINE POTENTIAL IN A RABBIT/S. SCABIEI VAR. CANIS MODEL
2013Co-Authors: Pearly Harumal, Bart J. Currie, Larry G. Arlian, Shelley F. Walton, Deborah C. Holt, Marjorie Morgan, Jurgen Rode, J. KempAbstract:Abstract. Sarcoptes scabiei (“itchmite”) causes Scabies, a disease of considerable human and veterinary significance. Little work has been done at the molecular level because of the difficulty of obtaining mites. We have used mites in skin from the bedding of crusted Scabies patients for the construction of a library of 10 5 cDNAs from S. scabiei var. hominis cloned in the vector pGEX4T-2. We describe the isolation by immunoscreening of 2 clones, one of which (Ssag1) is homologous to and cross-reactive with the house dust mite Euroglyphus maynei allergen M-177, an apolipoprotein from hemolymph. Immunohistochemistry revealed that it is located around the internal organs and cuticle of the mite and in eggs. Although it was not found to be protective in a challenge trial, the rabbits did not exhibit typical crust characteristics. This work shows that it is now possible to conduct such challenge trials withcloned Scabies antigens
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antibody responses to sarcoptes scabiei apolipoprotein in a porcine model relevance to immunodiagnosis of recent infection
PLOS ONE, 2013Co-Authors: Bart J. Currie, Shelley F. Walton, James S. Mccarthy, Deborah C. Holt, Cielo Pasay, Melanie Rampton, Andrew Kelly, Kate E. MounseyAbstract:No commercial immunodiagnostic tests for human Scabies are currently available, and existing animal tests are not sufficiently sensitive. The recombinant Sarcoptes scabiei apolipoprotein antigen Sar s 14.3 is a promising immunodiagnostic, eliciting high levels of IgE and IgG in infected people. Limited data are available regarding the temporal development of antibodies to Sar s 14.3, an issue of relevance in terms of immunodiagnosis. We utilised a porcine model to prospectively compare specific antibody responses to a primary infestation by ELISA, to Sar s 14.3 and to S. scabiei whole mite antigen extract (WMA). Differences in the antibody profile between antigens were apparent, with Sar s 14.3 responses detected earlier, and declining significantly after peak infestation compared to WMA. Both antigens resulted in >90% diagnostic sensitivity from weeks 8–16 post infestation. These data provide important information on the temporal development of humoral immune responses in Scabies and further supports the development of recombinant antigen based immunodiagnostic tests for recent Scabies infestations.
Larry G. Arlian - One of the best experts on this subject based on the ideXlab platform.
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Sarcoptes scabiei: genomics to proteomics to biology
Parasites & Vectors, 2016Co-Authors: Larry G. Arlian, Marjorie S. Morgan, S. Dean RiderAbstract:Background The common Scabies mite, Sarcoptes scabiei is a cosmopolitan parasite of humans and other mammals. An annotated genome of Sarcoptes scabiei var. canis has been deposited in the National Center for Biotechnology Information (NCBI) and VectorBase and a proteomic analysis of proteins in extracts of mite bodies and eggs from this strain has been reported. Here we mined the data to identify predicted proteins that are known to be involved in specific biological processes in other animals. Results We identified predicted proteins that are associated with immunomodulation of the host defense system, and biological processes of the mite including oxygen procurement and aerobic respiration, oxidative metabolism, sensory reception and locating a host, neuronal transmission, stressors (heat shock proteins), molting, movement, nutrient procurement and digestion, and excretion and water balance. We used these data to speculate that certain biological processes may occur in Scabies mites. Conclusion This analysis helps understand the biology of Sarcoptes scabiei var. canis and adds to the data already available in NCBI and VectorBase.
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a proteomic analysis of sarcoptes scabiei acari sarcoptidae
Journal of Medical Entomology, 2016Co-Authors: Marjorie S. Morgan, Larry G. Arlian, Dean S Rider, William C Grunwald, David R CoolAbstract:The pruritic skin disease Scabies is caused by the burrowing of the itch mite Sarcoptes scabiei (De Geer). It is difficult to diagnose this disease because its symptoms often resemble those of other skin diseases. No reliable blood or molecular diagnostic test is available. The aim of this project was to begin to characterize the Scabies proteome to identify Scabies mite proteins, including those that may be useful in the development of a diagnostic test or vaccine. Various Scabies mite extracts were separated by two-dimensional electrophoresis, and 844 Coomassie Blue-stained protein spots were excised, subjected to trypsin digestion, and analyzed by Matrix Assisted Laser Desorption/Ionization Time-Of-Flight/Time-Of-Flight (MALDI-TOF/TOF) mass spectrometry (MS). Tryptic fragment sequences determined by MS were searched against the recently completed S. scabiei annotated genome, leading to the identification of >150 proteins. Only 10 proteins hit to previously identified Scabies proteins including actin, tropomyosin, and several ABC transporters. Thirteen proteins had homology to dust mite allergens (members of groups 8, 10, 13, 17, 20, 25, and 28). Most other sequences showed some homology to proteins in other mites and ticks including homologs of calmodulin, calreticulin, lipocalin, and glutathione-S-transferase. These data will now allow the identification of the proteins to which Scabies patients produce antibodies, including those that may be good candidates for inclusion in a diagnostic test and vaccine.
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The Potential for a Blood Test for Scabies
PLoS neglected tropical diseases, 2015Co-Authors: Larry G. Arlian, Hermann Feldmeier, Marjorie S. MorganAbstract:Background Scabies afflicts millions of people worldwide, but it is very difficult to diagnose by the usual skin scrape test, and a presumptive diagnosis is often made based on clinical signs such as rash and intense itch. A sensitive and specific blood test to detect Scabies would allow a physician to quickly make a correct diagnosis. Objective Our objective was to profile the mite-specific antibodies present in the sera of patients with ordinary Scabies. Methods Sera of 91 patients were screened for Ig, IgD, IgE, IgG and IgM antibodies to S. scabiei, as well as to the house dust mites Dermatophagoides farinae, D. pteronyssinus and Euroglyphus maynei. Results 45%, 27% and 2.2% of the patients had measurable amounts of mixed Ig, IgG and IgE that recognized Scabies mite antigens. However, 73.6% of the Scabies patients had serum IgM that recognized Scabies proteins, and all except two of them also had IgM that recognized all of the three species of dust mites. No patient had serum antibody exclusively reactive to Scabies mite antigens. Conclusions Co-sensitization or cross-reactivity between antigens from Scabies and house dust mites confounds developing a blood test for Scabies.
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CDNA LIBRARY FROM SARCOPTES SCABIEI VAR. HOMINIS AND EVALUATION OF ITS VACCINE POTENTIAL IN A RABBIT/S. SCABIEI VAR. CANIS MODEL
2013Co-Authors: Pearly Harumal, Bart J. Currie, Larry G. Arlian, Shelley F. Walton, Deborah C. Holt, Marjorie Morgan, Jurgen Rode, J. KempAbstract:Abstract. Sarcoptes scabiei (“itchmite”) causes Scabies, a disease of considerable human and veterinary significance. Little work has been done at the molecular level because of the difficulty of obtaining mites. We have used mites in skin from the bedding of crusted Scabies patients for the construction of a library of 10 5 cDNAs from S. scabiei var. hominis cloned in the vector pGEX4T-2. We describe the isolation by immunoscreening of 2 clones, one of which (Ssag1) is homologous to and cross-reactive with the house dust mite Euroglyphus maynei allergen M-177, an apolipoprotein from hemolymph. Immunohistochemistry revealed that it is located around the internal organs and cuticle of the mite and in eggs. Although it was not found to be protective in a challenge trial, the rabbits did not exhibit typical crust characteristics. This work shows that it is now possible to conduct such challenge trials withcloned Scabies antigens
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acaricidal activity of eugenol based compounds against Scabies mites
PLOS ONE, 2010Co-Authors: Cielo Pasay, Larry G. Arlian, Marjorie S. Morgan, Kate E. Mounsey, D Vyszenskimoher, Graeme Irvine Stevenson, Rohan A Davis, Katherine Thea Andrews, James S. MccarthyAbstract:Backgound Human Scabies is a debilitating skin disease caused by the “itch mite” Sarcoptes scabiei. Ordinary Scabies is commonly treated with topical creams such as permethrin, while crusted Scabies is treated with topical creams in combination with oral ivermectin. Recent reports of acaricide tolerance in Scabies endemic communities in Northern Australia have prompted efforts to better understand resistance mechanisms and to identify potential new acaricides. In this study, we screened three essential oils and four pure compounds based on eugenol for acaricidal properties. Methodology/Principal Findings Contact bioassays were performed using live permethrin-sensitive S. scabiei var suis mites harvested from pigs and permethrin-resistant S. scabiei var canis mites harvested from rabbits. Results of bioassays showed that clove oil was highly toxic against Scabies mites. Nutmeg oil had moderate toxicity and ylang ylang oil was the least toxic. Eugenol, a major component of clove oil and its analogues –acetyleugenol and isoeugenol, demonstrated levels of toxicity comparable to benzyl benzoate, the positive control acaricide, killing mites within an hour of contact. Conclusions The acaricidal properties demonstrated by eugenol and its analogues show promise as leads for future development of alternative topical acaricides to treat Scabies.
