Tick innate immune responses to hematophagy and Ehrlichia infection at single-cell resolution

Introduction

Ticks rely on robust cellular and humoral responses to control microbial infection. However, several aspects of the tick's 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. 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 illuminating their function in vector competence and to help identify novel targets for developing new strategies to block tick-borne pathogen transmission.

Methods

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. The functional role of differentially expressed hemocyte markers in hemocyte proliferation and Ehrlichia dissemination was determined using an RNA interference approach.

Results and discussion

Our data exhibit the identification of fourteen distinct hemocyte populations. Our results uncover seven distinct lineages present in uninfected and Ehrlichia-infected hemocyte clusters. The functional characterization of hemocytin, cystatin, fibronectin, and lipocalin demonstrate their role in hemocyte population changes, proliferation, and Ehrlichia dissemination.

Conclusion

Our results uncover the tick immune responses to Ehrlichia infection and hematophagy at a single-cell resolution. 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.

Ehrlichia chaffeensis Co-Opts Phagocytic Hemocytes for Systemic Dissemination in the Lone Star Tick, Amblyomma americanum

INTRODUCTION

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.

METHODS

We utilized injection of clodronate liposome to deplete tick granulocytes combined with infection with E. chaffeensis to demonstrate their essential role in microbial infection.

RESULTS

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 tissue-associated hemocytes. We demonstrate that 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 that 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.

CONCLUSION

This study has identified multiple roles for granulocytic hemocytes in the control and systemic dissemination of E. chaffeensis infection.

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.

Ehrlichia chaffeensis co-opts phagocytic hemocytes for systemic dissemination in the Lone Star tick, Amblyomma americanum

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 Ehrlichi a 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.

Rickettsia parkeri hijacks tick hemocytes to manipulate cellular and humoral transcriptional responses

Introduction

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.

Methods

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.

Results and discussion

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 hemocyte-specific 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-two Drosophila homologs), significantly reduced hemocyte phagocytosis.

Conclusion

Together, these findings represent a significant step forward in understanding how hemocytes regulate microbial homeostasis and vector competence.

Hematophagy and tick-borne Rickettsial pathogen shape the microbial community structure and predicted functions within the tick vector, Amblyomma maculatum

Background

Ticks are the primary vectors of emerging and resurging pathogens of public health significance worldwide. Analyzing tick bacterial composition, diversity, and functionality across developmental stages and tissues is crucial for designing new strategies to control ticks and prevent tick-borne diseases.

Materials and methods

Here, we explored the microbial communities across the developmental timeline and in different tissues of the Gulf-Coast ticks (Amblyomma maculatum). Using a high-throughput sequencing approach, the influence of blood meal and Rickettsia parkeri, a spotted fever group rickettsiae infection in driving changes in microbiome composition, diversity, and functionality was determined.

Results

This study shows that the core microbiome of Am. maculatum comprises ten core bacterial genera. The genus Rickettsia, Francisella, and Candidatus_Midichloria are the key players, with positive interactions within each developmental stage and adult tick organ tested. Blood meal and Rickettsia parkeri led to an increase in the bacterial abundance in the tissues. According to functional analysis, the increase in bacterial numbers is positively correlated to highly abundant energy metabolism orthologs with blood meal. Correlation analysis identified an increase in OTUs identified as Candidatus Midichloria and a subsequent decrease in Francisella OTUs in Rickettsia parkeri infected tick stages and tissues. Results demonstrate the abundance of Rickettsia and Francisella predominate in the core microbiome of Am. maculatum, whereas Candidatus_Midichloria and Cutibacterium prevalence increase with R. parkeri-infection. Network analysis and functional annotation suggest that R. parkeri interacts positively with Candidatus_Midichloria and negatively with Francisella.

Conclusion

We conclude that tick-transmitted pathogens, such as R. parkeri establishes infection by interacting with the core microbiome of the tick vector.

Rickettsia parkeri infection modulates the sialome and ovariome of the Gulf coast tick, Amblyomma maculatum

The Gulf Coast tick, Amblyomma maculatum, is a vector of several tick-borne pathogens, including Rickettsia parkeri. The ability of R. parkeri to persist within the tick population through transovarial and transstadial transmission, without apparently harming the ticks, contributes to the pathogen's perpetuation in the tick population. Previous studies have shown that the R. parkeri load in A. maculatum is regulated by the tick tissues' oxidant/antioxidant balance and the non-pathogenic tick microbiome. To obtain further insights into the interaction between tick and pathogen, we performed a bulk RNA-Seq for differential transcriptomic analysis of ovaries and salivary glands from R. parkeri-infected and uninfected ticks over the feeding course on a host. The most differentially expressed functional category was of bacterial origin, exhibiting a massive overexpression of bacterial transcripts in response to the R. parkeri infection. Candidatus Midichloria mitochondrii and bacteria from the genus Rickettsia were mainly responsible for the overexpression of bacterial transcripts. Host genes were also modulated in R. parkeri-infected tick organs. A similar number of host transcripts from all analyzed functional categories was negatively and positively modulated, revealing a global alteration of the A. maculatum transcriptome in response to pathogen infection. R. parkeri infection led to an increase in salivary transcripts involved in blood feeding success as well as a decrease in ovarian immune transcripts. We hypothesize that these transcriptional alterations facilitate pathogen persistence and transmission within tick population.

Pre-Caesarean Section Vaginal Preparation with Chlorhexidine Solution in Preventing Puerperal Infectious Morbidities: A Randomized Controlled Trial

BACKGROUND

Globally, peripartum or puerperal infections account for about one tenth of maternal mortality, most of which occur in low income countries. Therefore, vaginal preparation with an antiseptic prior to a caesarean delivery could be considered an additional measure to prevent subsequent infectious morbidities.

OBJECTIVES

To evaluate vaginal preparation with 0.3% chlorhexidine solution in the prevention of endometritis, surgical site infection and post-operative fever following emergency caesarean section.

METHODS

This prospective randomized controlled trial (RCT) was conducted among 240 participants planned for emergency caesarean sections (CS) at term in the University of Medical Sciences Teaching Hospital Complex, Ondo State, Nigeria. Participants were randomised into either group "A" (study) or "B" (control). The former had vaginal preparation with 0.3% chlorhexidine gluconate immediately after anaesthesia while the latter received normal saline. Participants were followed up post-operatively during which clinical features of puerperal infectious morbidities were observed for each during admission as well as 8th and 14th days after delivery.

RESULTS

The rate and risk of endometritis were significantly lower in the study group compared to the control; 5.0% versus 13.3%, respectively (chi squared =5.004; p=0.042, RR = 0.38; 95% CI = 0.15-0.94; p = 0.042; RRR = 0.62). Post-operative fever and surgical site infection, were also lower in the study group compared to the controls, but the difference was not statistically significant.

CONCLUSION

When compared to placebo, pre-caesarean section vaginal preparation with 0.3% chlorhexidine solution significantly reduced only the rate and risk of post-operative endometritis among infectious morbidities.

Recently Evolved Francisella-Like Endosymbiont Outcompetes an Ancient and Evolutionarily Associated Coxiella-Like Endosymbiont in the Lone Star Tick (Amblyomma americanum) Linked to the Alpha-Gal Syndrome

Background

Ticks are hematophagous arthropods that transmit various bacterial, viral, and protozoan pathogens of public health significance. The lone star tick (Amblyomma americanum) is an aggressive human-biting tick that transmits bacterial and viral pathogens, and its bites are suspected of eliciting the alpha-gal syndrome, a newly emerged delayed hypersensitivity following consumption of red meat in the United States. While ongoing studies have attempted to investigate the contribution of different tick-inherent factors to the induction of alpha-gal syndrome, an otherwise understudied aspect is the contribution of the tick microbiome and specifically obligate endosymbionts to the establishment of the alpha-gal syndrome in humans.

Materials and Methods

Here we utilized a high-throughput metagenomic sequencing approach to cataloging the entire microbial communities residing within different developmental stages and tissues of unfed and blood-fed ticks from laboratory-maintained ticks and three new geographical locations in the United States. The Quantitative Insights Into Microbial Ecology (QIIME2) pipeline was used to perform data analysis and taxonomic classification. Moreover, using a SparCC (Sparse Correlations for Compositional data) network construction model, we investigated potential interactions between members of the microbial communities from laboratory-maintained and field-collected ticks.

Results

Overall, Francisellaceae was the most dominant bacteria identified in the microbiome of both laboratory-raised and field-collected Am. americanum across all tissues and developmental stages. Likewise, microbial diversity was seen to be significantly higher in field-collected ticks compared with laboratory-maintained ticks as seen with a higher number of both Operational Taxonomic Units and measures of species richness. Several potential positive and negative correlations were identified from our network analysis. We observed a strong positive correlation between Francisellaceae, Rickettsiaceae, and Midichloriaceae in both developmental stages and tissues from laboratory-maintained ticks, whereas ovarian tissues had a strong positive correlation of bacteria in the family Xanthobacteraceae and Rhizobiaceae. A negative interaction was observed between Coxiellaceae and Francisellaceae in Illinois, and all the bacteria detected from ticks from Delaware were negatively correlated.

Conclusion

This study is the first to catalog the microbiome of Am. americanum throughout its developmental stages and different tissue niches and report the potential replacement of Coxiellaceae by Francisellaceae across developmental stages and tissues tested except in ovarian tissues. These unique and significant findings advance our knowledge and open a new avenue of research to further understand the role of tick microbiome in tick-borne diseases and develop a holistic strategy to control alpha-gal syndrome.

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 northern and southern geographic locations in the USA. Using a SparCC network construction model, we performed potential interactions between members of the microbial communities from Borrelia burgdorferi–infected tissues of unfed and blood-fed ticks. A significant difference in bacterial composition and diversity 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. The 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 need more validation and understanding. Understanding the interplay between the microbiome and tick-borne pathogens within tick vectors may pave the way for new strategies to prevent tick-borne infections.

Psychiatric morbidity among undergraduate students of university of Ilorin, Kwara state, Nigeria

Introduction

The Nigerian tertiary education system admits mostly teenagers and young adults from different ethno-religious and family backgrounds, some of whom may have inherent risks and predisposition to mental illness. They then undergo stressful conditions related to the university life such as long durations of lectures, over-crowding, and lack of social amenities, haphazard lecture schedules as well as incessant industrial strike actions of academic and non- academic staff. In spite of these, there appears to be few studies on the burden of emotional and mental disorders among Nigerian University students, and none was cited suggesting interventions that may be appropriate.

Objectives

The objectives of the study is to determine the prevalence of psychiatric morbidity and its associated factors among undergraduate students of Univesity of Ilorin

Methods

This is a cross-sectional study using multi staged systematic randomization. A self-administered socidemographic questionnaire and the 12 item general health questionnaire (GHQ -12) was administered on 3,300 students.

Results

Psychiatric morbidity was found to be 23.6% of the 3179 analyzable returned questionnaires. Factors found to be significantly associated with psychiatric morbidity included female gender, relationship with parents, parental employment status and family structure. Students on scholarship were more likely to have mental illness. Other associated factors include whether course of study was the preferred one and relationships with peers and lecturers on campus. About 46.6% of the students were willing to have internet based mental health intervention programmes.

Conclusions

The data obtained from this study is relevant for the formation of mental health promotion and prevention programs on our campus.

Disclosure

this study is part of the first phase of a three phase study. it aims to explore the factors associated with psychiatric morbidity among University student as a precursor for determining appropriate mental health interventions. it was partly funded by the

Using the new ICD-MM classification system for attribution of cause of maternal death--a pilot study

Understanding the causes of and factors contributing to maternal deaths is critically important for development of interventions that reduce the global burden of maternal mortality and morbidity. The International Classification of Diseases-Maternal Mortality (ICD-MM) classification of cause of death during pregnancy, childbirth and the puerperium was applied to data obtained from maternal death reviews (MDR) for 4558 maternal deaths from five countries in sub-Saharan Africa. None of the data sets identified type of maternal death. Information obtained via MDR is generally sufficient to agree on classification of cause of death to the levels of type and group. The terms 'underlying cause of death' and 'contributing conditions' were used differently in different settings and a specific underlying cause of death was frequently not recorded. Application of ICD-MM resulted in the reclassification of 3.1% (9/285) of cases to the group 'unanticipated complications of management', previously recorded as obstetric haemorrhage or unknown. An increased number of cases were assigned to the groups pregnancy-related infection (5.6-10.2%) and pregnancies with abortive outcome (3.4-4.9%) when a clear distinction was made between women who died 'with' HIV/AIDS of obstetric causes (direct maternal death) and AIDS-related indirect maternal deaths (group 'non-obstetric complications'). Similarly, anaemia and obstructed labour were more frequently identified as contributing factors than underlying cause of death. It would be helpful if MDR forms could have explicitly stated variables called: type, group and underlying cause of death as well as a dedicated section to the most frequently occurring contributing conditions recognised in that setting.

Proximate and phytochemical of Cola nitida and Cola acuminata

The aim of the research was to examine Cola nitida and Cola acuminata for their phytochemical and proximate compositions. Presence of secondary metabolites do provide information about the plants for their potentials as a lead candidates for the novel drug discovery. The proximate analysis was done using the method of Association of Official Analytical Chemists (AOAC) and the phytochemical analysis was done using methods of Markkar and Goodchild for tannin, Brunner for saponin, Harbone for alkaloid and Bohm and Koupai-Abyazani for flavonoid. The proximate results showed that the moisture content of Cola acuminata and Cola nitida were in the range of 9.73-9.81%, ash 2.72-2.21%, fat 3.02-2.20%, protein 19.14-15.24%, crude fiber 7.30-4.18% and carbohydrate 58.09 66.45%. Cola acuminate has more protein content, ash and fat than Cola nitida. The result of phytochemical analysis showed that Cola acuminata has more alkaloids (2.22%), tannin (6.46%) and saponin (8.06%) than Cola nitida. The phenol contents of the two kola nuts were the same range 0.27%, the flavonoid were in the range of 0.12-0.14%. The presence of secondary metabolites in these plants are indications that if well researched, novel bioactive compounds can be discovered in them as there are worldwide efforts by scientists looking for new bioactive compounds to combat various ailments which have developed high resistant to already known antibiotics.

The characteristics of the menstrual cycle in Nigerian schoolgirls and the implications for school health programmes

The present study examines the characteristics of menstrual cycle among 361 Nigerian postmenarcheal schoolgirls derived from seven public secondary schools. Survey questions covered preparation for menstruation, duration of flow, cycle length, regularity, premenstrual syndrome and dysmenorrhea. For the study subjects the mean age (years) at the time of interview, at menarche, and completed since menarche are 16.5 +/- 3.3, 13.7 +/- 2.6 and 2.9 +/- 1.2 respectively. Premenstrual counselling was reported in 84.2%; and 48.6% was provided by parents and guardians, and 23.7% by school teachers. The findings indicate that menstrual flow < or = 2 days, and cycle length < or = 20 days are common; occurring in 20-30% of schoolgirls. Abnormal patterns such as cycle length > or = 38 days, flow duration > or = 8 days and heavy menstruation occurred in less than 5% of study subjects. Irregular menstrual cycles were recorded in 13%, and severe dysmenorrhea in 17.2%. Severe premenstrual syndrome occurred in about 20% of schoolgirls, with symptom-complex mainly of behavioural change, arousal and impaired concentration. The need for a multi-disciplinary school health counselling program that would provide relevant information on menstrual pattern and its common variation, identify abnormal patterns for early referral, provide psychological support and drug relief of distressing menstrual symptoms, and provide information on other contemporary adolescent problems is discussed.