Biology subjects

Adegoke, A.

Publications and source records attributed to Adegoke, A..

8 recordsLinked to original sources

bioRxiv2026

Insights into tick-pathogen interactions - a single cell RNA sequencing approach of transcriptional changes during ehrlichial infection

Tick-borne diseases represent a significant threat to human and animal health worldwide. In the United States, the blacklegged tick, Ixodes scapularis (I. scapularis), serves as a competent vector for several bacterial pathogens, including Ehrlichia muris eauclairensis (EME). The I. scapularis embryonic cell line (ISE6) is a valuable tool for propagating tick-borne pathogens and studying tick-pathogen interactions. In this study, we examined the cellular complexity of ISE6 cells and their response to EME infection. Single-cell RNA sequencing revealed 15 distinct cell clusters present. Although ISE6 cells are heterogeneous, they do not display transcriptional similarity to any known tick tissues. Notably, this lack of similarity did not influence their susceptibility to EME infection. Our results demonstrated that EME infection induces time-dependent transcriptional changes in ISE6 cells: early infection is characterized by upregulation of genes associated with stress adaptation, mitochondrial function, and metabolic pathways, whereas late infection leads to broad downregulation of genes involved in the cell cycle, DNA replication, and cytoskeletal organization. These findings enhance our understanding of ehrlichial interactions with ISE6 cells and reinforce the utility of this cell line as a resource for isolating and propagating arthropod endosymbionts and tick-borne pathogens. IMPORTANCEThis study provides a single-cell resolution framework for interpreting tick cell line biology during infection with a medically relevant ehrlichial pathogen. Using scRNA-seq, we show that the I. scapularis embryonic-derived ISE6 cell line comprises multiple transcriptionally distinct cell states, yet these states do not map cleanly onto canonical tick tissue signatures, even when compared against a curated reference tissue atlas. Despite this heterogeneity, EME broadly infects ISE6 cell population, indicating that susceptibility is not restricted to a specific cell type. We further define a time-dependent arthropod vector response in which early infection is marked by activation of stress and metabolic adaptation response, followed by late-stage inhibition of key signaling, transcriptional, and proliferative pathways as bacterial burden increases. Together, these findings strengthen the biological interpretation of ISE6 as an in vitro model for tick-pathogen interactions and provide a resource for future mechanistic studies of ehrlichial persistence, replication, and vector competence.

molecular biology↗

bioRxiv2023

Ticks without borders: Microbial communities of immature Neotropical tick species parasitizing migratory landbirds along northern Gulf of Mexico

The long-distance, seasonal migrations of birds make them an effective ecological bridge for the movement of ticks. The introduction of exotic tick species to new geographical regions can lead to the emergence of novel tick-borne pathogens or the re-emergence of previously eradicated ones. This study assessed the prevalence of exotic tick species parasitizing resident, short-distance, and long-distance songbirds during spring and autumn at stopover sites in the northern Gulf of Mexico using the mitochondrial 12S rDNA gene. Birds were captured for tick collection from six different sites from late August to early November in both 2018 and 2019. The highest number of ticks were collected in the 2019 season. Most ticks were collected off the Yellow-breasted Chat (Icteria virens) and Common Yellowthroat (Geothlypis trichas), and 54% of the total ticks collected were from Grand Chenier, LA. A high throughput 16S ribosomal RNA sequencing approach was followed to characterize the microbial communities and identify pathogenic microbes in all tick samples. Tick microbial communities, diversity, and community structure were determined using quantitative insight into microbial ecology (QIIME). The sparse correlations for compositional data (SparCC) approach was then used to construct microbial network maps and infer microbial correlations. A total of 421 individual ticks in the genera Amblyomma, Haemaphysalis, and Ixodes were recorded from 28 songbird species, of which Amblyomma and Amblyomma longirostre was the most abundant tick genus and species, respectively. Microbial profiles showed that Proteobacteria was the most abundant phylum. The most abundant bacteria include the pathogenic Rickettsia and endosymbiont Francisella, Candidatus Midichloria, and Spiroplasma. BLAST analysis and phylogenetic reconstruction of the Rickettsia sequences revealed the highest similarities to pathogenic spotted and non-spotted fever groups, including R. buchneri, R. conorii, R. prowazekii, R. bellii, R. australis, R. parkeri, R. monacensis, and R. monteiroi. Permutation multivariate analysis of variance revealed that the relative abundance of Francisella and Rickettsia drives microbial patterns across the tick genera. We also observed a higher percentage of positive correlations in microbe-microbe interactions among members of the microbial communities. Network analysis suggested a negative correlation between a) Francisella and Rickettsia and, b) Francisella and Cutibacterium. Lastly, mapping the distributions of bird species parasitized during spring migrations highlighted geographic hotspots where migratory songbirds could disperse ticks and their pathogens at stopover sites or upon arrival to their breeding grounds, the latter showing means dispersal distances from 421-5003 kilometers. These findings strongly highlight the potential role of migratory birds in the epidemiology of tick-borne pathogens. O_FIG O_LINKSMALLFIG WIDTH=99 HEIGHT=200 SRC="FIGDIR/small/563347v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@5b100borg.highwire.dtl.DTLVardef@7a59f3org.highwire.dtl.DTLVardef@a78ff3org.highwire.dtl.DTLVardef@dbce25_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphic abstract:C_FLOATNO Overview of the experimental approach for bird collection and characterization of neotropical ticks microbiome. A) Birds migrating through the Mississippi flyway into the United States were trapped and captured for identification and tick collection and B) immature developmental stages of feeding ticks infesting the birds were carefully removed and stored for morphological and molecular identification of tick species. C) Tick DNA was used for the PCR amplification of arthropods mitochondrial 12S rDNA and amplicons were sequenced and compared to deposited datasets in NCBI database. D) Microbial DNA was isolated using V3-V4 16S primers and unique barcodes attached to amplified 16S sequences prior to Illumina MiSeq sequences. E) Distribution and contribution of birds to tick infestation, and distribution and community profiles of sequenced microbial communities. C_FIG

zoology↗

bioRxiv2023

Tick Innate Immune Responses to Hematophagy and Ehrlichia Infection at Single-Cell Resolution

Ticks rely on robust cellular and humoral immune responses to control microbial infection. However, several aspects of the ticks innate immune system remain uncharacterized, most notably that of the immune cells (called hemocytes), which are known to play a significant role in cellular and humoral responses toward microbes. Despite the importance of hemocytes in regulating microbial infection, our understanding of their basic biology and molecular mechanisms remains limited. Therefore, we believe that a more detailed understanding of the role of hemocytes in the interactions between ticks and tick-borne microbes is crucial to illuminate their function in vector competence and to help identify novel targets for developing new strategies to block tick-borne pathogen transmission. This study examined hemocytes from the lone star tick (Amblyomma americanum) at the transcriptomic level using the 10X genomics single-cell RNA sequencing platform to analyze hemocyte populations from unfed, partially blood-fed, and Ehrlichia chaffeensis-infected ticks. Our data exhibit the identification of twelve and nineteen distinct hemocyte populations, respectively, from uninfected and Ehrlichia-infected ticks. Our results show a significant increase of clusters representing granulocyte and oenocytoids populations with Ehrlichia infection. This work opens a new field of tick innate immunobiology to understand the role of hemocytes, particularly in response to prolonged blood-feeding (hematophagy) and tick-microbial interactions. SignificanceThe immune response of ticks plays a crucial role in their ability to survive and transmit pathogens. Hemocytes, the primary immune cells in arthropods, are key mediators of ticks immune defense and provide deep insights into immune responses to microbial infection. However, tick hemocytes cellular complexity and heterogeneity have posed challenges for comprehensive characterization. This study employed single-cell RNA sequencing (scRNA-seq) to profile tick hemocytes and elucidate their transcriptional diversity. We identified distinct subpopulations of hemocytes and characterized their unique gene expression profiles. We observed significant variation in immune-related gene expression between hemocyte subpopulations during hematophagy and in response to Ehrlichia infection, suggesting specialized functional roles. Our analysis revealed potential marker genes associated with specific hemocyte functions. Our study provides the first comprehensive single-cell atlas of tick hemocytes, shedding light on these cells molecular diversity and immune functions. The findings enhance our understanding of tick-host interactions and offer a step toward understanding arthropod immunobiology.

immunology↗

bioRxiv2023

co-opts phagocytic hemocytes for systemic dissemination in the Lone Star tick, .

Hematophagous arthropods can acquire and transmit several pathogens of medical importance. In ticks, the innate immune system is crucial in the outcome between vector-pathogen interaction and overall vector competence. However, the specific immune response(s) elicited by the immune cells known as hemocytes remains largely undefined in Ehrlichia chaffeensis and its competent tick vector, Amblyomma americanum. Here, we show that granulocytes, professional phagocytic cells, are integral in eliciting immune responses against commensal and pathogen infection. The chemical depletion of granulocytes led to decreased phagocytic efficiency of tissues-associated hemocytes. We demonstrate E. chaffeensis can infect circulating hemocytes, and both cell-free plasma and hemocytes from E. chaffeensis-infected ticks can establish Ehrlichia infection in recipient ticks. Lastly, we provide evidence to show granulocytes play a dual role in E. chaffeensis infection. Depleting granulocytic hemocytes increased Ehrlichia load in the salivary gland and midgut tissues. In contrast, granulocyte depletion led to a reduced systemic load of Ehrlichia. This study has identified multiple roles for granulocytic hemocytes in the control and systemic dissemination of E. chaffeensis infection.

immunology↗

bioRxiv2022

Rickettsia parkeri Hijacks Tick Hemocytes to Manipulate Cellular and Humoral Transcriptional Responses

Blood-feeding arthropods rely on robust cellular and humoral immunity to control pathogen invasion and replication. Tick hemocytes produce factors that can facilitate or suppress microbial infection and pathogenesis. Despite the importance of hemocytes in regulating microbial infection, understanding of their basic biology and molecular mechanisms remains limited. Here we combined histomorphology and functional analysis to identify five distinct phagocytic and non-phagocytic hemocyte populations circulating within the Gulf Coast tick Amblyomma maculatum. Depletion of phagocytic hemocytes using clodronate liposomes revealed their function in eliminating bacterial infection. We provide the first direct evidence that an intracellular tick-borne pathogen, Rickettsia parkeri, infects phagocytic hemocytes in Am. maculatum to modify tick cellular immune responses. A massive RNA-seq dataset generated from hemocytes isolated from uninfected and R. parkeri-infected partially blood-fed ticks generated [~]40,000 differentially regulated transcripts, >11,000 of which were immune genes. Silencing two differentially regulated phagocytic immune marker genes (nimrod B2 and eater) significantly reduced hemocyte phagocytosis. Together, these findings represent a significant step forward in understanding how hemocytes regulate microbial homeostasis and vector competence.

immunology↗

bioRxiv2021

An exploratory study on the microbiome of northern and southern populations of Ixodes scapularis ticks predicts changes and unique bacterial interactions

The black-legged tick (Ixodes scapularis) is the primary vector of Borrelia burgdorferi, the causative agent of Lyme disease in North America. However, the prevalence of Lyme borreliosis is clustered around the northern states of the United States of America. This study utilized a metagenomic sequencing approach to compare the microbial communities residing within Ix. scapularis populations from north and southern geographic locations in the USA. Using a SparCC network construction model, potential interactions between members of the microbial communities from Borrelia burgdorferi-infected tissues of unfed and blood-fed ticks were performed. A significant difference in bacterial composition and diversity among northern and southern tick populations was found between northern and southern tick populations. The network analysis predicted a potential antagonistic interaction between endosymbiont Rickettsia buchneri and Borrelia burgdorferi sensu lato. Network analysis, as expected, predicted significant positive and negative microbial interactions in ticks from these geographic regions, with the genus Rickettsia, Francisella, and Borreliella playing an essential role in the identified clusters. Interactions between Rickettsia buchneri and Borrelia burgdorferi sensu lato needs more validation and understanding. Understanding the interplay between the micro-biome and tick-borne pathogens within tick vectors may pave the way for new strategies to prevent tick-borne infections.

zoology↗

bioRxiv2021

Changes in microbial composition, diversity, and functionality in the Amblyomma maculatum microbiome following infection with Rickettsia parkeri

BackgroundTicks are the primary vectors for emerging and resurging pathogens of public health significance worldwide. Examining tick bacterial composition, diversity, and functionality across developmental stages and tissues is necessary for designing new strategies to control ticks and prevent tick-borne diseases. MethodsA high-throughput sequencing approach was used to determine the influence of blood meal and Rickettsia parkeri infection on changes in Amblyomma maculatum microbiome composition, diversity, and functionality across the developmental timeline and in different tissues. Quantitative insight into microbial ecology analysis allowed us to determine microbial population structure, composition, and diversity. A non-metric multidimensional scaling, the sparse correlations for compositional data (SparCC) module, and phylogenetic investigation of communities by reconstruction of unobserved states 2 (PICRUSt2) software were used in the assessment. ResultsThe Amblyomma maculatum microbiome comprises ten bacterial genera present across tick life cycle stages. Among the top ten bacterial genera (the core tick microbiome), Rickettsia, Francisella, and Candidatus Midichloria are the key players, with positive interactions within each developmental stage and adult tick organ tested. The bacterial abundances, based on the number of operational taxonomic units (OTUs), increase with blood meal in each stage, helping bacterial floral growth. The growth in bacterial numbers is related to highly abundant energy metabolism orthologs with blood meal, according to functional analysis. Whereas R. parkeri had a positive correlation with Candidatus Midichloria during the tick life cycle, based on the increased number of OTUs and network analysis, this was due to an increased level of metabolic activity. Interestingly, R. parkeri replaces Francisella, based on the lower level of OTUs representing Francisella in R. parkeri-infected ticks (in all stages/organs) and negatively correlated according to network and linear discriminant analysis effect size (LEfSe). ConclusionsWe found that Rickettsia and Francisella predominate in the core microbiome of the Gulf Coast tick, whereas Candidatus Midichloria and Cutibacterium levels increase with infection. Network analysis and functional annotation suggest that R. parkeri interacts positively with Candidatus Midichloria and negatively with Francisella and that metabolic profiles are upregulated with blood meal and R. parkeri infection. Overall, this is the first study to determine the combinatorial outcome of blood meal and pathogen interaction on microbiome composition over the developmental stages of Am. maculatum. This new study expands on our existing knowledge of the Am. maculatum microbiome and further highlights the need to investigate pathogen-symbiont interactions between R. parkeri and Francisella or Candidatus Midichloria to facilitate the development of strategies for controlling tick-transmitted diseases. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=146 SRC="FIGDIR/small/465777v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@1c30a2aorg.highwire.dtl.DTLVardef@1d0713borg.highwire.dtl.DTLVardef@1b9eadborg.highwire.dtl.DTLVardef@e9f5ad_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG

microbiology↗

bioRxiv2020

Tick-Borne bacterial and protozoan animal pathogens shape the native microbiome within Hyalomma anatolicum anatolicum and Rhipicephalus microplus tick vectors

BackgroundTicks vector a variety of bacterial, viral, and protozoan pathogens of public and animal health significance. Ticks also harbor a diverse community of microbes linked with their biological processes like hematophagy and hence vector competence. The interactions between bacterial and/or protozoan pathogens and their tick vector microbiome are yet to be investigated. In lieu of this, this study was designed to define the microbial composition of uninfected and infected Hyalomma (H.) anatolicum anatolicum and Rhipicephalus (R.) microplus tick species. Methodology/Principal findingsA total of 320 H. anatolicum and R. microplus were screened for the presence of the protozoan (Theileria sp.), and bacterial (Anaplasma marginale) pathogens by PCR. Subsequently, the microbiome of uninfected and infected individual H. anatolicum and R. microplus were analyzed. The highly conserved V1-V3 region of the 16S rRNA gene was sequenced using the MiSeq Illumina platform. The microbiome of female H. anatolicum anatolicum ticks was dominated by the endosymbiont Candidatus Midichloria mitochondrii (CMM) and Francisella-like endosymbiont (FLE) which were not affected by pathogen infection. Ehrlichia species was detected in A. marginale-infected male H. anatolicum anatolicum (6.2%) as opposed to the Theileria sp.-infected female H. anatolicum anatolicum. Coxiella sp. was also detected in uninfected (2.96%) and A. marginale-infected (4.25%), but not in Theileria sp.-infected R. microplus ticks. Analysis of the eukaryote composition in the respectively ticks also revealed the presence of operational taxonomic units (OTUs) belonging to Plasmodium (P.) falciparum in Theileria sp.-infected H. a. anatolicum and R. microplus ticks, while Hepatozoon americanum detected from Theileria sp.-infected and uninfected H. a. anatolicum. Conclusion and SignificanceThis study establishes the extent of the diversity of microbial community of two important tick species from Pakistan and also revealed the presence of Theileria and A. marginale and additional pathogenic bacteria that could be of public health significance. We hypothesized that infection with either a protozoan or bacterial pathogen will alter the microbial composition within these tick species. Interestingly, we reported the detection of the malarial parasite (P. falciparum) from ticks infected with the protozoan pathogen (Theileria sp.). Further validation experiments are required on endosymbionts and pathogens of ticks to investigate how they could be important in the epidemiology of human and animal pathogens.

zoology↗