Despite the significant health risks associated with Dermanyssus gallinae infestations in humans, they are often overlooked. This study investigated a household case of D. gallinae infestation and explored the resulting clinical manifestations and risk of infection in family members. Microfluidic PCR was employed for high-throughput screening of pathogens in collected mites and blood samples from both chickens and family members. Morphological and molecular examinations confirmed the identity of the mites as D. gallinae sensu stricto (s.s.), with evidence indicating recent blood feeding. Results indicated that the mites exclusively harbored various pathogens, including Bartonella spp., Ehrlichia spp., Apicomplexa, and Theileria spp. Blood samples from family members and poultry tested negative for these pathogens, suggesting a potential reservoir role for D. gallinae. The study further identified haplotypes of D. gallinae, classifying them into D. gallinae s.s., cosmopolitan haplogroup A. Serological analysis revealed elevated IgE seroreactivity against mite proteins in the family member with bite lesions. Antibodies against Bartonella spp. were detected in this individual, indicating exposure to the pathogen. In summary, this study sheds light on the clinical manifestations, pathogen detection, and genetic characterization of D. gallinae infestations, underscoring the necessity of adopting comprehensive approaches to manage such infestations effectively.

• Keywords
• Allergy, One health, Pathogens, Red mites,
• Publication type
• Journal Article MeSH

A novel Bartonella-like symbiont (BLS) of Tyrophagus putrescentiae was characterized. BLS formed a separate cluster from the Bartonella clade together with an ant symbiont. BLS was present in mite bodies (103 16S DNA copies/mite) and feces but was absent in eggs. This indicated the presence of the BLS in mite guts. The BLS showed a reduction in genome size (1.6 Mb) and indicates gene loss compared to Bartonella apis. The BLS can be interacted with its host by using host metabolic pathways (e.g., the histidine and arginine metabolic pathways) as well as by providing its own metabolic pathways (pantothenate and lipoic acid) to the host, suggesting the existence of a mutualistic association. Our experimental data further confirmed these potential mutualistic nutritional associations, as cultures of T. putrescentiae with low BLS abundance showed the strongest response after the addition of vitamins. Despite developing an arguably tight dependency on its host, the BLS has probably retained flagellar mobility, as evidenced by the 32 proteins enriched in KEGG pathways associated with flagellar assembly or chemotaxis (e.g., fliC, flgE, and flgK, as highly expressed genes). Some of these proteins probably also facilitate adhesion to host gut cells. The microcin C transporter was identified in the BLS, suggesting that microcin C may be used in competition with other gut bacteria. The 16S DNA sequence comparison indicated a mite clade of BLSs with a broad host range, including house dust and stored-product mites. Our phylogenomic analyses identified a unique lineage of arachnid specific BLSs in mites and scorpions.IMPORTANCEA Bartonella-like symbiont was found in an astigmatid mite of allergenic importance. We assembled the genome of the bacterium from metagenomes of different stored-product mite (T. putrescentiae) cultures. The bacterium provides pantothenate and lipoic acid to the mite host. The vitamin supply explains the changes in the relative abundance of BLSs in T. putrescentiae as the microbiome response to nutritional or pesticide stress, as observed previously. The phylogenomic analyses of available 16S DNA sequences originating from mite, scorpion, and insect samples identified a unique lineage of arachnid specific forming large Bartonella clade. BLSs associated with mites and a scorpion. The Bartonella clade included the previously described Ca. Tokpelaia symbionts of ants.

• Keywords
• Bartonella, ants, house dust, mite, nutrition, stored-product, symbionts, vitamin,
• MeSH
• Acaridae * microbiology   MeSH
• Allergens MeSH
• Bacteria MeSH
• Bartonella * genetics   MeSH
• Thioctic Acid * MeSH
• Mites * genetics   MeSH
• Symbiosis MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Allergens MeSH
• Thioctic Acid * MeSH

Endosymbiotic bacteria significantly impact the fitness of their arthropod hosts. Dermanyssus gallinae, the poultry red mite, is a blood-feeding ectoparasite that exclusively feeds on avian blood. While there is a relatively comprehensive understanding of its microbial community structures across developmental stages based on 16S rRNA sequencing， the functional integration of these microbes within the host's physiology remains elusive. This study aims to elucidate the role of symbiotic bacteria in D. gallinae biology. 16S rRNA amplicon sequencing and fluorescence in situ hybridization revealed a prominent midgut-confinement bacterial microbiota with considerable diversity, out of which Kocuria and Bartonella A acted as the predominant bacterial genera inhabiting D. gallinae. The relative abundance of Bartonella A increased rapidly after blood-sucking, suggesting its adaptation to a blood-based diet and its pivotal role in post-engorgement activities. Some of the isolated bacterial strains from D. gallinae display hemolytic activity on blood agar, potentially aiding blood digestion. To corroborate this in vivo, antibiotic-mediated clearance was exploited to generate dysbiosed cohorts of D. gallinae mites, lacking some of the key bacterial species. Phenotypic assessments revealed that dysbiosed mites experienced delayed blood digestion and diminished reproductive capacity. Whole-genome sequencing identified Bartonella A as a new species within the genus Bartonella, exhibiting characteristics of an obligate symbiont. These findings underscore the significance of microbiota in poultry red mites and suggest microbiota-targeted strategies for controlling mite populations in poultry farms.

• Keywords
• Bartonella A, antibiotic treatment, blood digestion, poultry red mite, reproduction, symbiotic bacteria,
• Publication type
• Journal Article MeSH

Bacterial microbiota play an important role in the fitness of arthropods, but the bacterial microflora in the parasitic mite Dermanyssus gallinae is only partially explored; there are gaps in our understanding of the microbiota localization and in our knowledge of microbial community assembly. In this work, we have visualized, quantified the abundance, and determined the diversity of bacterial occupancy, not only across developmental stages of D. gallinae, but also in the midgut of micro-dissected female D. gallinae mites. We explored community assembly and the presence of keystone taxa, as well as predicted metabolic functions in the microbiome of the mite. The diversity of the microbiota and the complexity of co-occurrence networks decreased with the progression of the life cycle. However, several bacterial taxa were present in all samples examined, indicating a core symbiotic consortium of bacteria. The relatively higher bacterial abundance in adult females, specifically in their midguts, implicates a function linked to the biology of D. gallinae mites. If such an association proves to be important, the bacterial microflora qualifies itself as an acaricidal or vaccine target against this troublesome pest.

• Keywords
• Dermanyssus gallinae, Functional prediction, Keystone taxa, Microbial networks, Microbiome,
• MeSH
• Bacteria genetics   MeSH
• Mite Infestations * parasitology   prevention & control   MeSH
• Chickens parasitology   MeSH
• Poultry Diseases * parasitology   prevention & control   MeSH
• Mites * microbiology   MeSH
• Life Cycle Stages MeSH
• Animals MeSH
• Check Tag
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Dermatophagoides farinae is inhabited by an intracellular bacterium, Cardinium. Using correlations between host and symbiont gene expression profiles, we identified several important molecular pathways that potentially regulate/facilitate their interactions. The expression of Cardinium genes collectively explained 95% of the variation in the expression of mite genes assigned to pathways for phagocytosis, apoptosis, the MAPK signaling cascade, endocytosis, the tumor necrosis factor (TNF) pathway, the transforming growth factor beta (TGF-β) pathway, lysozyme, and the Toll/Imd pathway. In addition, expression of mite genes explained 76% of the variability in Cardinium gene expression. In particular, the expression of the Cardinium genes encoding the signaling molecules BamD, LepA, SymE, and VirD4 was either positively or negatively correlated with the expression levels of mite genes involved in endocytosis, phagocytosis, and apoptosis. We also found that Cardinium possesses a complete biosynthetic pathway for lipoic acid and may provide lipoate, but not biotin, to mites. Cardinium gene expression collectively explained 84% of the variation in expression related to several core mite metabolic pathways, and, most notably, a negative correlation was observed between bacterial gene expression and expression of mite genes assigned to the glycolysis and citric acid cycle pathways. Furthermore, we showed that Cardinium gene expression is correlated with expression levels of genes associated with terpenoid backbone biosynthesis. This pathway is important for the synthesis of pheromones, thus providing an opportunity for Cardinium to influence mite reproductive behavior to facilitate transmission of the bacterium. Overall, our study provided correlational gene expression data that can be useful for future research on mite-Cardinium interactions. IMPORTANCE The molecular mechanisms of mite-symbiont interactions and their impacts on human health are largely unknown. Astigmatid mites, such as house dust and stored-product mites, are among the most significant allergen sources worldwide. Although mites themselves are the main allergen sources, recent studies have indicated that mite-associated microbiomes may have implications for allergen production and human health. The major medically important house dust mite, D. farinae, is known to harbor a highly abundant intracellular bacterium belonging to the genus Cardinium. Expression analysis of the mite and symbiont genes can identify key mite molecular pathways that facilitate interactions with this endosymbiont and possibly shed light on how this bacterium affects mite allergen production and physiology in general.

• Keywords
• Cardinium, allergens, endosymbiont, host-pathogen interactions, house dust mite, interactions, symbiont, transcriptome,
• Publication type
• Journal Article MeSH

Arthropod-associated microorganisms are important because they affect host fitness, protect hosts from pathogens, and influence the host's ability to vector pathogens. Stored product mites (Astigmata) often establish large populations in various types of food items, damaging the food by direct feeding and introducing contaminants, including their own bodies, allergen-containing feces, and associated microorganisms. Here we access the microbial structure and abundance in rearing diets, eggs, feces fraction, and mite bodies of 16 mite populations belonging to three species (Carpoglyphus lactis, Acarus siro, and Tyrophagus putrescentiae) using quantitative PCR and 16S ribosomal RNA (rRNA) gene amplicon sequencing. The mite microbiomes had a complex structure dominated by the following bacterial taxa (OTUs): (a) intracellular symbionts of the genera Cardinium and Wolbachia in the mite bodies and eggs; (b) putative gut symbionts of the genera Solitalea, Bartonella, and Sodalis abundant in mite bodies and also present in mite feces; (c) feces-associated or environmental bacteria of the genera Bacillus, Staphylococcus, and Kocuria in the diet, mite bodies, and feces. Interestingly and counterintuitively, the differences between microbial communities in various conspecific mite populations were higher than those between different mite species. To explain some of these differences, we hypothesize that the intracellular bacterial symbionts can affect microbiome composition in mite bodies, causing differences between microbial profiles. Microbial profiles differed between various sample types, such as mite eggs, bodies, and the environment (spent growth medium-SPGM). Low bacterial abundances in eggs may result in stochastic effects in parent-offspring microbial transmission, except for the intracellular symbionts. Bacteria in the rearing diet had little effect on the microbial community structure in SPGM and mite bodies. Mite fitness was positively correlated with bacterial abundance in SPGM and negatively correlated with bacterial abundances in mite bodies. Our study demonstrates critical host-microbe interactions, affecting all stages of mite growth and leading to alteration of the environmental microbiome. Correlational evidence based on absolute quantitation of bacterial 16S rRNA gene copies suggests that mite-associated microorganisms are critical for modulating important pest properties of mites by altering population growth.

• Keywords
• Allergen, Bartonella, Cardinium, Eggs, Feces, Feeding, Mite, Symbionts, Wolbachia,
• MeSH
• Acaridae classification   growth & development   microbiology   MeSH
• Bacteria classification   genetics   isolation & purification   MeSH
• Diet MeSH
• Feces microbiology   MeSH
• Phylogeny MeSH
• Host Microbial Interactions MeSH
• Microbiota * MeSH
• Ovum microbiology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH

The two common species of house dust mites (HDMs), Dermatophagoides farinae and D. pteronyssinus, are major sources of allergens in human dwellings worldwide. Many allergens from HDMs have been described, but their extracts vary in immunogens. Mite strains may differ in their microbiomes, which affect mite allergen expression and contents of bacterial endotoxins. Some bacteria, such as the intracellular symbiont Cardinium, can affect both the sex ratio and biochemical pathways of mites, resulting in abundance variations of mite allergens/immunogens. Here, we investigated the bacterial microbiomes of D. farinae and D. pteronyssinus males and females using barcode 16S rDNA sequencing, qPCR, and genomic data analysis. We found a single species of Cardinium associated with D. farinae strains from the USA, China and Europe. Cardinium had high abundance relative to other bacterial taxa and represented 99% of all bacterial DNA reads from female mites from the USA. Cardinium was also abundant with respect to the number of host cells-we estimated 10.4-11.8 cells of Cardinium per single female mite cell. In a European D. farinae strain, Cardinium was more prevalent in females than in males (representing 92 and 67% of all bacterial taxa in females and males, respectively). In contrast, D. pteronyssinus lacked any Cardinium species, and the microbiomes of male and female mites were similar. We produced a Cardinium genome assembly (1.48 Mb; GenBank: PRJNA555788, GCA_007559345.1) associated with D. farinae. The ascertained ubiquity and abundance of Cardinium strongly suggest that this intracellular bacterium plays an important biological role in D. farinae.

• Keywords
• Acaridida, Allergen production, Astigmata, Cardinium, Dermatophagoides pteronyssinus, Microbiome,
• MeSH
• Bacteroidetes isolation & purification   MeSH
• Dermatophagoides farinae microbiology   MeSH
• Dermatophagoides pteronyssinus microbiology   MeSH
• Genome, Bacterial * MeSH
• Microbiota MeSH
• Whole Genome Sequencing MeSH
• Symbiosis MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• China MeSH
• Europe MeSH
• United States MeSH

The functional relevance of microbiota is a key aspect for understanding host-microbiota interactions. Mammalian skin harbours a complex consortium of beneficial microorganisms known to provide health and immune-boosting advantages. As yet, however, little is known about functional microbial communities on avian feathers, including their co-evolution with the host and factors determining feather microbiota (FM) diversity. Using 16S rRNA profiling, we investigated how host species identity, phylogeny and geographic origin determine FM in free-living passerine birds. Moreover, we estimated the relative abundance of bacteriocin-producing bacteria (BPB) and keratinolytic feather damaging bacteria (FDB) and evaluated the ability of BPB to affect FM diversity and relative abundance of FDB. Host species identity was associated with feather bacterial communities more strongly than host geographic origin. FM functional properties differed in terms of estimated BPB and FDB relative abundance, with both showing interspecific variation. FM diversity was negatively associated with BPB relative abundance across species, whereas BPB and FDB relative abundance was positively correlated. This study provides the first thorough evaluation of antimicrobial peptides-producing bacterial communities inhabiting the feather integument, including their likely potential to mediate niche-competition and to be associated with functional species-specific feather microbiota in avian hosts.

• MeSH
• Bacteria classification   genetics   isolation & purification   MeSH
• Bacteriocins biosynthesis   MeSH
• Species Specificity MeSH
• Phylogeny MeSH
• Host Specificity MeSH
• Microbiota * MeSH
• Feathers microbiology   MeSH
• Birds microbiology   MeSH
• RNA, Ribosomal, 16S genetics   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Bacteriocins MeSH
• RNA, Ribosomal, 16S MeSH

Interactions with microorganisms might enable house dust mites (HDMs) to derive nutrients from difficult-to-digest structural proteins and to flourish in human houses. We tested this hypothesis by investigating the effects of changes in the mite culture growth and population of two HDM species on HDM microbiome composition and fitness. Growing cultures of laboratory and industrial allergen-producing populations of Dermatophagoides farinae (DFL and DFT, respectively) and Dermatophagoides pteronyssinus (DPL and DPT, respectively) were sampled at four time points. The symbiotic microorganisms of the mites were characterized by DNA barcode sequencing and quantified by qPCR using universal/specific primers. The population growth of mites and nutrient contents of mite bodies were measured and correlated with the changes in bacteria in the HDM microbiome. The results showed that both the population and culture age significantly influenced the microbiome profiles. Cardinium formed 93% and 32% of the total sequences of the DFL and DFT bacterial microbiomes, respectively, but this bacterial species was less abundant in the DPL and DPT microbiomes. Staphylococcus abundance was positively correlated with increased glycogen contents in the bodies of mites, and increased abundances of Aspergillus, Candida, and Kocuria were correlated with increased lipid contents in the bodies of mites. The xerophilic fungus Wallemia accounted for 39% of the fungal sequences in the DPL microbiome, but its abundance was low in the DPT, DFL, and DFT microbiomes. With respect to the mite culture age, we made three important observations: the mite population growth from young cultures was 5-8-fold higher than that from old cultures; specimens from old cultures had greater abundances of fungi and bacteria in their bodies; and yeasts predominated in the gut contents of specimens from young cultures, whereas filamentous mycelium prevailed in specimens from old cultures. Our results are consistent with the hypothesis that mites derive nutrients through associations with microorganisms.

• Keywords
• Bacteria, Dermatophagoides farinae, Dermatophagoides pteronyssinus, Diet, Fungi, Gut, Nutrition, Symbiosis, Yeasts,
• MeSH
• Bacteria * classification   MeSH
• RNA, Bacterial analysis   MeSH
• Species Specificity MeSH
• RNA, Fungal analysis   MeSH
• Fungi * classification   MeSH
• Real-Time Polymerase Chain Reaction MeSH
• Microbiota * MeSH
• Population Dynamics MeSH
• Pyroglyphidae microbiology   physiology   MeSH
• RNA, Ribosomal, 16S analysis   MeSH
• RNA, Ribosomal, 18S analysis   MeSH
• DNA Barcoding, Taxonomic MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• RNA, Bacterial MeSH
• RNA, Fungal MeSH
• RNA, Ribosomal, 16S MeSH
• RNA, Ribosomal, 18S MeSH

Background: Tyrophagus putrescentiae is a ubiquitous mite species in soil, stored products and house dust and infests food and causes allergies in people. T. putrescentiae populations harbor different bacterial communities, including intracellular symbionts and gut bacteria. The spread of microorganisms via the fecal pellets of T. putrescentiae is a possibility that has not been studied in detail but may be an important means by which gut bacteria colonize subsequent generations of mites. Feces in soil may be a vector for the spread of microorganisms. Methods: Extracts from used mite culture medium (i.e., residual food, mite feces, and dead mite bodies) were used as a source of feces-inhabiting microorganisms as food for the mites. Two T. putrescentiae populations (L and P) were used for experiments, and they hosted the intracellular bacteria Cardinium and Wolbachia, respectively. The effects of the fecal fraction on respiration in a mite microcosm, mite nutrient contents, population growth and microbiome composition were evaluated. Results: Feces from the P population comprised more than 90% Bartonella-like sequences. Feces from the L population feces hosted Staphylococcus, Virgibacillus, Brevibacterium, Enterobacteriaceae, and Bacillus. The mites from the P population, but not the L population, exhibited increased bacterial respiration in the microcosms in comparison to no-mite controls. Both L- and P-feces extracts had an inhibitory effect on the respiration of the microcosms, indicating antagonistic interactions within feces-associated bacteria. The mite microbiomes were resistant to the acquisition of new bacterial species from the feces, but their bacterial profiles were affected. Feeding of P mites on P-feces-enriched diets resulted in an increase in Bartonella abundance from 6 to 20% of the total bacterial sequences and a decrease in Bacillus abundance. The population growth was fivefold accelerated on P-feces extracts in comparison to the control. Conclusion: The mite microbiome, to a certain extent, resists the acquisition of new bacteria when mites are fed on feces of the same species. However, a Bartonella-like bacteria-feces-enriched diet seems to be beneficial for mite populations with symbiotic Bartonella-like bacteria. Coprophagy on the feces of its own population may be a mechanism of bacterial acquisition in T. putrescentiae.

• Keywords
• Bartonella, bacteria, diets, feces, feeding, fungi, soil, transmission,
• Publication type
• Journal Article MeSH