‘Eliska,’ an endangered black rhino ( Diceros bicornis ), died suddenly in Mkomazi National Park in Tanzania in 2016. Three Amblyomma gemma ticks were collected from Eliska's body, and four ticks were collected from the surrounding field. We conducted 16S rRNA targeted high-throughput sequencing to evaluate the overall composition of bacteria in the ticks' microbiomes and investigate whether the ticks could be the cause of Eliska's death. The ticks collected from Eliska's body and the field were found to differ in their bacterial composition. Bacillus chungangensis and B. pumilus were the most commonly found bacteria in the ticks collected from the field, and B. cereus and Lysinibacillus sphaericus were the most commonly found in the ticks collected from Eliska's body. The abundance was higher in the ticks collected from the field. In contrast, the equity was higher in the ticks collected from Eliska's body. No known pathogenic bacteria that could explain Eliska's sudden death were found in any of the ticks. The differences between the microbiome of ticks collected from Eliska's body and from the field indicate that the microbiome of ticks' changes through the consumption of blood.

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Background Major allergen sources Dermatophagoides farinae, Dermatophagoides pteronyssinus and Tyrophagus putrescentiae have been reported to have distinct microbiomes. The purpose of this study was to investigate the effect of each mite on airway epithelial cells as a model of airway allergic disease. Methods Transcriptomic analysis (RNA‐seq) of an airway epithelial cell line (BEAS‐2B) was performed to compare gene expression patterns after treatment with extracts of three mite species (D. farinae, D. pteronyssinus and T. putrescentiae). In addition, mycobiome deep sequencing of mites was employed to identify fungal species that interact with the microbiomes of the mites. Results Immune responses to bacteria were enriched only in the D. farinae‐treated group as this species harboured larger numbers of bacteria than the other mites, and the high level of LPS in D. farinae caused proinflammatory cytokine production in airway epithelial cells. In addition, antibiotic metabolism pathways were enriched in D. pteronyssinus‐treated cells but not in D. farinae ‐treated cells. Subsequent experiments revealed that D. pteronyssinus had a high fungal load that inhibited bacterial survival in this mite species. Conclusion The large amount of bacteria in D. farinae causes airway epithelial cells to produce more allergy‐related cytokines than D. pteronyssinus, since fungi present in D. pteronyssinus suppress the abundance of mite‐associated bacteria.

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Purpose Allergens present in the feces or frass of cockroaches can cause allergic sensitization in humans. The use of fecal and frass extracts for immunotherapy has been previously investigated but has not yet been fully standardized. Here, we treated cockroaches with ampicillin to produce extracts with reduced amounts of total bacteria. Methods We performed targeted high-throughput sequencing of 16S rDNA to compare the microbiomes of ampicillin-treated and untreated (control) cockroaches. RNA-seq was performed to identify differentially expressed genes (DEGs) in ampicillin-treated cockroaches. Results Analysis of the microbiome revealed that alpha diversity was lower in the ampicillin-treated group than in the control group. Beta diversity analysis indicated that ampicillin treatment altered bacterial composition in the microbiome of cockroaches. Quantitative polymerase chain reaction revealed that almost all bacteria were removed from ampicillin-treated cockroaches. RNA-seq analysis revealed 1,236 DEGs in ampicillin-treated cockroaches (compared to untreated cockroaches). Unlike bacterial composition, the DEGs varied between the two groups. Among major allergens, the expression of Bla g 2 decreased significantly in ampicillin-treated cockroaches (compared to untreated group). Conclusions In this study, the reduced level of allergens observed in cockroaches may be related to lower amounts of total bacteria caused by treatment with antibiotics. It is possible to make a protein extract with few bacteria for use in immunotherapy.