The Role of Dust Mites in Allergy Miller, Jeffrey D.
Clinical reviews in allergy & immunology,
12/2019, Volume:
57, Issue:
3
Journal Article
Peer reviewed
House dust mites are an unsurpassed cause of atopic sensitization and allergic illness throughout the world. The major allergenic dust mites
Dermatophagoides pteronyssinus
,
Dermatophagoides farinae
...,
Euroglyphus maynei
, and
Blomia tropicalis
are eight-legged members of the Arachnid class. Their approximately 3-month lifespan comprises egg, larval, protonymph, tritonymph, and adult stages, with adults, about one fourth to one third of a millimeter in size, being at the threshold of visibility. The geographic and seasonal distributions of dust mites are determined by their need for adequate humidity, while their distribution within substrates is further determined by their avoidance of light. By contacting the epithelium of the eyes, nose, lower airways, skin, and gut, the allergen-containing particles of dust mites can induce sensitization and atopic symptoms in those organs. Various mite allergens, contained primarily in mite fecal particles but also in shed mite exoskeletons and decaying mite body fragments, have properties that include proteolytic activity, homology with the lipopolysaccharide-binding component of Toll-like receptor 4, homology with other invertebrate tropomyosins, and chitin-cleaving and chitin-binding activity. Mite proteases have direct epithelial effects including the breaching of tight junctions and the stimulation of protease-activated receptors, the latter inducing pruritus, epithelial dysfunction, and cytokine release. Other components, including chitin, unmethylated mite and bacterial DNA, and endotoxin, activate pattern recognition receptors of the innate immune system and act as adjuvants promoting sensitization to mite and other allergens. Clinical conditions resulting from mite sensitization and exposure include rhinitis, sinusitis, conjunctivitis, asthma, and atopic dermatitis. Systemic allergy symptoms can also occur from the ingestion of cross-reacting invertebrates, such as shrimp or snail, or from the accidental ingestion of mite-contaminated foods. Beyond their direct importance as a major allergen source, an understanding of dust mites leads to insights into the nature of atopy and of allergic sensitization in general.
Dermanyssus gallinae, also known as the poultry red mite (PRM), is a blood-feeding ectoparasite of poultry and sylvatic birds. This mite is endemic in many parts of the globe and poses a threat to ...the egg industry, while compromising the health and welfare of hens, both directly and as a vector of diseases. In addition, people attacked by D. gallinae may develop gamasoidosis. Despite the high prevalence in several European countries, epidemiological information on D. gallinae in Portugal is scarce. This study aimed to assess the prevalence and infestation levels in laying farms in Portugal and evaluate the perception and attitudes of producers regarding D. gallinae. A survey was performed between August 2016 - November 2017, which included 24 farms in the NUTS2 regions Centro and Norte. Mites were sampled with corrugated cardboard traps and the perception and attitudes of farmers regarding the PRM were evaluated with the European COREMI questionnaire prepared by WG 1 of the COST action FA1404. D. gallinae was detected in 95.8% of farms (95% CI: 79.8-99.3%). The average number of trapped mites among farms was 5200 ± 16,522, with a median of 359 mites (interquartile range = 46-3135). Results from the questionnaire show that insufficient monitoring, under-detection and late and suboptimal treatment may contribute to the maintenance of significant infestation levels. The present data highlight the need for adequate monitoring of D. gallinae, timely action and effective treatment in order to improve poultry productivity and ensure human and animal health and welfare.
RESEARCH HIGHLIGHTS
A survey on the prevalence of D. gallinae in Portuguese layer farms is presented
The perceived importance of D. gallinae was assessed with a questionnaire
D. gallinae was detected in 95.8% of farms
The results emphasize the need for adequate monitoring and treatment optimization.
Poultry red mites (PRMs, Dermanyssus gallinae) are ectoparasites that negatively affect farmed chickens, leading to serious economic losses worldwide. Acaricides have been used to control PRMs in ...poultry houses. However, some PRMs have developed resistance to acaricides, and therefore different approaches are required to manage the problems caused by PRMs. Vaccination of chickens is one of the methods being considered to reduce the number of PRMs in poultry houses. In a previous study, a cysteine protease, Deg-CPR-1, was identified as a candidate vaccine against PRMs distributed in Europe. In this study, we investigated the characteristics of Deg-CPR-1. A phylogenetic analysis revealed that Deg-CPR-1 is closely related to the digestive cysteine proteases of other mite species, and it was classified into a cluster different from that of chicken cathepsins. Deg-CPR-1 of PRMs in Japan has an amino acid substitution compared with that of PRMs in Europe, but it showed efficacy as a vaccine, consistent with previous findings. Deg-CPR-1 exhibited cathepsin L-like enzyme activity. In addition, the Deg-CPR-1 mRNA was expressed in the midgut and in all stages of PRMs that feed on blood. These results imply that Deg-CPR-1 in the midgut may have important functions in physiological processes, and the inhibition of its expression may contribute to the efficacy of a Deg-CPR-1-based vaccine. Further research is required to fully understand the mechanisms of vaccine efficacy.
Parasites and other symbionts are crucial components of ecosystems, regulating host populations and supporting food webs. However, most symbiont systems, especially those involving commensals and ...mutualists, are relatively poorly understood. In this study, we have investigated the nature of the symbiotic relationship between birds and their most abundant and diverse ectosymbionts: the vane‐dwelling feather mites. For this purpose, we studied the diet of feather mites using two complementary methods. First, we used light microscopy to examine the gut contents of 1,300 individual feather mites representing 100 mite genera (18 families) from 190 bird species belonging to 72 families and 19 orders. Second, we used high‐throughput sequencing (HTS) and DNA metabarcoding to determine gut contents from 1,833 individual mites of 18 species inhabiting 18 bird species. Results showed fungi and potentially bacteria as the main food resources for feather mites (apart from potential bird uropygial gland oil). Diatoms and plant matter appeared as rare food resources for feather mites. Importantly, we did not find any evidence of feather mites feeding upon bird resources (e.g., blood, skin) other than potentially uropygial gland oil. In addition, we found a high prevalence of both keratinophilic and pathogenic fungal taxa in the feather mite species examined. Altogether, our results shed light on the long‐standing question of the nature of the relationship between birds and their vane‐dwelling feather mites, supporting previous evidence for a commensalistic–mutualistic role of feather mites, which are revealed as likely fungivore–microbivore–detritivore symbionts of bird feathers.
The common waxbill, Estrilda astrild (L., 1758) (Passeriformes: Estrildidae) is a small passerine bird native to Sub-Saharan Africa that has been introduced into several regions of the world.
In the ...present paper, eight mite species (Acariformes) are reported from this host from Brazil, including three species new to science: Montesauria caravela n. sp., M. conquistador n. sp. (Proctophyllodidae), Trouessartia transatlantica n. sp., T. minuscula Gaud & Mouchet, 1958, T. estrildae Gaud & Mouchet, 1958 (Trouessartiidae), Onychalges pachyspathus Gaud, 1968 (Pyroglyphidae), Paddacoptes paddae (Fain, 1964) (Dermationidae) and Neocheyletiella megaphallos (Lawrence, 1959) (Cheyletidae). Comparative material from Africa was also studied.
These mites represent at least three morpho-ecological groups regarding their microhabitats occupied on the bird: (i) vane mites (Montesauria and Trouessartia on the large wing and tail feathers); (ii) down mites (Onychalges); and (iii) skin mites (Paddacoptes and Neocheyletiella). On one bird individual we found representatives of all eight mite species. Although the common waxbill was introduced to the Neotropical region almost two centuries ago, we demonstrate that it still retains its Old World acarofauna and has not yet acquired any representatives of typical Neotropical mite taxa.
A research centre with 30,568 laying hens, kept in enriched cages and in aviaries, had become naturally infested with poultry red mites (PRM) in 32 of its 48 bird units. Therefore, at the age of 52 ...weeks all hens were treated with fluralaner through the drinking water. After this treatment, PRM were no longer observed. As all birds were of the same age, and since production figures were measured daily in all 48 units, this offered a unique opportunity to examine how PRM had affected performance. Statistical analyses were done to compare the evolution of production data from the pre-treatment to the post-treatment period in units that were visually free of PRM or infested with PRM to different levels. Production standards provided by the breeding organizations were used as a reference. The results demonstrated significant posttreatment increases of laying percentage, egg weight, egg mass, percentage first choice eggs, feed intake and body weight in heavily infested hens of one or both housing systems, as compared to the non-infested controls. These data confirm that PRM infestations can impact the main performance traits related to profitability of laying hen farms as well as the hens' general condition.
Poultry red mites (PRMs, Dermanyssus gallinae) are hematophagous ectoparasites that negatively affect egg production, which causes serious economic losses to the poultry industry worldwide. ...Currently, the emergence of acaricide-resistant PRMs has impeded PRM control in poultry farms. Several alternatives for acaricide use have been described for managing PRM-caused problems. Vaccination is among the methods for controlling PRMs in poultry houses. Currently, several candidates for vaccine antigens have been identified. This study identified a cysteine protease, Deg-CPR-2, which differs from 2 other previously reported cysteine proteases in PRMs, from previously obtained data from RNA-sequencing (RNA-seq) analysis. We investigated the characteristics of Deg-CPR-2 and assessed its efficacy as a vaccine antigen in vitro. Phylogenetic analysis revealed that Deg-CPR-2 belonged to a different cluster from those of other cysteine proteases in PRMs. This cluster also included cathepsin L-like proteases, enzymes thought to be involved in hemoglobin digestion in ticks. Expression analysis revealed Deg-CPR-2 expression in midguts and all the life-stages; however, there were differences in the expression levels across the life-stages. The enzyme activity of recombinant Deg-CPR-2 was inhibited in the presence of a cysteine protease inhibitor, which suggests that Deg-CPR-2 functions as a cysteine protease in PRMs. Finally, there was an in vitro increase in the mortality of PRMs, mainly protonymphs that were artificially fed with plasma from chickens immunized with Deg-CPR-2. These findings suggest that Deg-CPR-2 may contribute to protein digestion in the midgut of PRMs and is crucially involved in physiological processes in PRMs. Additionally, immunization with Deg-CPR-2 may reduce the number of protonymphs, and Deg-CPR-2 should be considered as a candidate antigen for anti-PRM vaccine development.
Dermanyssus gallinae, the poultry red mite, is a global threat to the commercial egg-laying industry. Control of D. gallinae is difficult, with only a limited number of effective pesticides and ...non-chemical treatments available. Here, we characterize the candidate vaccine antigen D. gallinae cathepsin D-1 (Dg-CatD-1) and demonstrate that purified refolded recombinant Dg-Cat-D1 (rDg-CatD-1) is an active aspartyl proteinase which digests haemoglobin with a pH optimum of pH 4. Soluble protein extracts from D. gallinae also have haemoglobinase activity, with a pH optimum comparable to the recombinant protein, and both proteinase activities were inhibited by the aspartyl proteinase inhibitor Pepstatin A. Enzyme activity and the ubiquitous localization of Dg-CatD-1 protein in sections of adult female mites is consistent with Dg-CatD-1 being a lysosomal proteinase. Using Dg-CatD-1 as a model vaccine antigen, we compared vaccine delivery methods in laying hens via vaccination with: (i) purified rDg-CatD-1 with Montanide™ ISA 71 VG adjuvant; (ii) recombinant DNA vaccines for expression of rDg-CatD-1 and (iii) transgenic coccidial parasite Eimeria tenella expressing rDg-CatD-1. In two independent trials, only birds vaccinated with rDg-CatD-1 with Montanide™ ISA 71 VG produced a strong and long-lasting serum anti-rDg-Cat-D1 IgY response, which was significantly higher than that in control birds vaccinated with adjuvant only. Furthermore, we showed that egg-laying rates of D. gallinae mites fed on birds vaccinated with rDg-CatD-1 in Montanide™ ISA 71 VG was reduced significantly compared with mites fed on unvaccinated birds.
RESEARCH HIGHLIGHTS
Dermanyssus gallinae cathepsin D-1 (Dg-CatD-1) digests haemoglobin
Vaccination of hens with rDg-CatD-1 in Montanide™ ISA 71 VG results in long-lasting IgY levels
Serum anti-rDg-CatD-1 antibodies reduce egg laying in D. gallinae after a single blood meal
Mites serve as pathogens, allergens, or microbial containers, which can seriously damage the health of humans and animals. The substantial amount of mite species and their similar morphology make it ...complicated to identify and classify. Our mouse breeder incidentally noticed papular-type erythema with itching and peeling of the skin in several places, and an investigation revealed that this symptom was caused by an uncommon parasite that appeared on the skin and around the nest of the mice. By morphological observation, DNA extraction, PCR amplification, and DNA sequencing, we roughly identified the category of the parasite as a mite. Then, we designed a specific primer cox1, amplified and sequenced the mitochondrial cox1 gene fragment of the mite, calculated the intraspecific and interspecific differences, and reconstructed the phylogenetic tree for sequence alignment. Finally, this species was identified and named this
Ornithonyssus bacoti-KF
. According to the ivermectin gradient test, we found that 0.1 mg/mL concentration of ivermectin solution was the most effective for mite removal in the bath, with no recurrence after 6 months of treatment.
Ornithonyssus bacoti
, diagnosed by microscopic exam and confirmed by PCR amplification sequencing, was treated with ivermectin to control the rodent-borne parasite effectively.
The cosmopolitan mite family Laelapidae includes both free-living predatory species and species associated with arthropods, mammals or birds. This work presents a list of free-living and ...arthropod-associated species of laelapids, with corresponding taxonomic information and references. It includes 1088 species (in addition to three subspecies) assigned to 73 genera, 61 new combinations and two new synonymies at the generic level. Laelaps (Apolaelaps) Silvestri is raised to the generic level. Many of the species described before about 1950 are poorly characterised and cannot be classified with confidence at the family or generic level. Hence, ten genera, one subgenus, 121 species (ca. 70% of which were reported as Hypoaspis Canestrini or Laelaps (Hypoaspis) Canestrini) and one subspecies, are considered incertae sedis, because of their inadequate morphological characterisation in the literature. Some of these may not even belong to the Laelapidae or to the groups of interest for this publication. A total of 89 species, 30 genera, one subgenus, one tribe and one subfamily previously associated with genera treated in this catalogue are now placed in other families or, less commonly, in laelapid genera not considered here because they are considered essentially vertebrate parasites (taxa excluded). Twenty-six other species (one cited as a "variety") are cited as nomina nuda. An illustrated key to the 73 genera included in the catalogue along with revised generic diagnoses are provided.
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