Arthropod Vectors Research Articles

Genetic characterization and pathogenic effects of Hepatozoon canis infection in police dogs in Egypt

BackgroundHepatozoon canis is a protozoan parasite transmitted to dogs through ingesting the arthropod vector (hard ticks), which contains mature protozoal oocysts harboring infectious sporozoites.AimsThis study aims to evaluate the blood parameters, biochemical assays and histopathological appraisal of infected police dogs with Hepatozoon canis, from kennels in the police academy of Egypt during 2020–2021.MethodsRed blood cells count, hemoglobin, hematocrit, blood platelets and white blood cells count from collected blood samples were analyzed, and serum albumin, creatinine, urea, aspartate aminotransferase and alanine aminotransferase were analyzed from serum samples. Polymerase chain reaction amplified the 18S ribosomal RNAgene of the Hepatozoon species for genetic analysis, and the deoxyribonucleic acid products were sequenced and added to GenBank.ResultsThe present study resulted in 5% of the police dog population being infested with Rhipicephalus sanguineus. This study registered the sequences of the Hepatozoon canis 18S ribosomal RNAgene in Egypt for the first time in Genbank (MW362244.1–MW362245.1). The biochemical assay revealed that the parasite severely affected the protein, significantly increasing serum albumin in positive polymerase chain reaction testing dogs.ConclusionA thorough inspection discovered that 100 police dogs had clinical symptoms like fever, emaciation and anemia, while the other 200 were healthy and had no evident clinical indicators.

Host skin immunity to arthropod vector bites: from mice to humans

Infections caused by vector-borne pathogens impose a significant burden of morbidity and mortality in a global scale. In their quest for blood, hematophagous arthropods penetrate the host skin and may transmit pathogens by the bite. These pathogens are deposited along with saliva and a complex mixture of vector derived factors. Hematophagous arthopod vectors have evolved a complex array of adaptations to modulate the host immune response at the bite site with the primary goal to improve blood feeding, which have been exploited throughout evolution by these pathogens to enhance infection establishment in the host. While this paradigm has been firmly established in mouse models, comparable data from human studies are scarce. Here we review how the host skin immune response to vector bites in animal models is hijacked by microbes to promote their pathogenesis. We mainly explored four distinct vector-pathogen pairs of global health importance: sand flies and Leishmania parasites, Ixodes scapularis ticks and Borrelia burgdorferi, Aedes aegypti mosquitoes and arboviruses, and Anopheles gambiae mosquitos and Plasmodium parasites. Finally, we outline how critical it is for the field of vector biology to shift from rodent models to clinical studies focused on the interface of vector-pathogen-host immune system to push further the frontiers of knowledge of the field.

Human-aided dispersal and population bottlenecks facilitate parasitism escape in the most invasive mosquito species.

During biological invasion process, species encounter new environments and partially escape some ecological constraints they faced in their native range, while they face new ones. The Asian tiger mosquito Aedes albopictus is one of the most iconic invasive species introduced in every inhabited continent due to international trade. It has also been shown to be infected by a prevalent yet disregarded microbial entomoparasite Ascogregarina taiwanensis. In this study, we aimed at deciphering the factors that shape the global dynamics of A. taiwanensis infection in natural A. albopictus populations. We showed that A. albopictus populations are highly colonized by several parasite genotypes but recently introduced ones are escaping it. We further performed experiments based on the invasion process to explain such pattern. To that end, we hypothesized that (i) mosquito passive dispersal (i.e. human-aided egg transportation) may affect the parasite infectiveness, (ii) founder effects (i.e. population establishment by a small number of mosquitoes) may influence the parasite dynamics, and (iii) unparasitized mosquitoes are more prompt to found new populations through active flight dispersal. The two first hypotheses were supported as we showed that parasite infection decreases over time when dry eggs are stored and that experimental increase in mosquitoes' density improves the parasite horizontal transmission to larvae. Surprisingly, parasitized mosquitoes tend to be more active than their unparasitized relatives. Finally, this study highlights the importance of global trade as a driver of biological invasion of the most invasive arthropod vector species.

Transcriptomic Investigation of the Virus Spectrum Carried by Midges in Border Areas of Yunnan Province.

Yunnan province in China shares its borders with three neighboring countries: Myanmar, Vietnam, and Laos. The region is characterized by a diverse climate and is known to be a suitable habitat for various arthropods, including midges which are notorious for transmitting diseases which pose significant health burdens affecting both human and animal health. A total of 431,100 midges were collected from 15 different locations in the border region of Yunnan province from 2015 to 2020. These midges were divided into 37 groups according to the collection year and sampling site. These 37 groups of midges were then homogenized to extract nucleic acid. Metatranscriptomics were used to analyze their viromes. Based on the obtained cytochrome C oxidase I gene (COI) sequences, three genera were identified, including one species of Forcipomyia, one species of Dasyhelea, and twenty-five species of Culicoides. We identified a total of 3199 viruses in five orders and 12 families, including 1305 single-stranded positive-stranded RNA viruses (+ssRNA) in two orders and seven families, 175 single-stranded negative-stranded RNA viruses (-ssRNA) in two orders and one family, and 1719 double-stranded RNA viruses in five families. Six arboviruses of economic importance were identified, namely Banna virus (BAV), Japanese encephalitis virus (JEV), Akabane virus (AKV), Bluetongue virus (BTV), Tibetan circovirus (TIBOV), and Epizootic hemorrhagic disease virus (EHDV), all of which are capable, to varying extents, of causing disease in humans and/or animals. The survey sites in this study basically covered the current distribution area of midges in Yunnan province, which helps to predict the geographic expansion of midge species. The complexity and diversity of the viral spectrum carried by midges identified in the study calls for more in-depth research, which can be utilized to monitor arthropod vectors and to predict the emergence and spread of zoonoses and animal epidemics, which is of great significance for the control of vector-borne diseases.

A molecular biology approach to identify Francisella tularensis proteins that interact with Band 3 of human erythrocytes.

Francisella tularensis is a pathogenic gram-negative bacterium that causes the zoonotic disease Tularemia. In addition, F. tularensis is classified as a Class A Bioterrorism agent by the CDC due to the ease of aerosolization and the ability of this bacterium to cause fatal infection in low doses. Previous studies suggest that invasion of mammalian erythrocytes by F. tularensis helps to increase colonization of ticks, an arthropod vector of this pathogen. Our laboratory previously found that the erythrocyte membrane glycoprotein, Band 3 is required by F. tularensis for invasion of red blood cells. Therefore, we predict that bacterial proteins interact with Band 3 to facilitate invasion. To identify these proteins, we will express codon-optimized Band 3 linked to a Glutathione-S transferase tag in F. tularensis LVS. Subsequent pull-down assays may reveal F. tularensis protein binding partners to Band 3 responsible for facilitating erythrocyte invasion.

Detection of Rickettsia species in rodents collected in the Northern provinces of Vietnam, 2020–2022

Rickettsiae, which are obligate intracellular bacterial parasites, have a life cycle commonly associated with arthropod vectors and animal hosts. Rodents are recognized as their natural reservoir hosts and play a role in transmitting the bacteria to humans through arthropod vectors. The true extent of rickettsial infections in Vietnam remains underestimated due to a limited understanding of the disease’s epidemiology, resulting in a significant public health burden.The aim of this investigation was to assess the prevalence of Rickettsia in wild-living rodents in Dien Bien, Son La, and Phu Tho provinces of Northern Vietnam between 2020 and 2022.Materials and methods. A total of 396 wild-living rodents were collected from the Northern provinces of Vietnam during 2020–2022. Real-time polymerase chain reaction (PCR) was employed to detect the percentage of Rickettsia-positive specimens. Subsequently, the ompB and 17kDa genes were extracted, amplified, and sequenced from the Rickettsia-positive rodents.Results and discussion. Among the 396 rodents examined, the majority were Rattus norvegicus (56.1%), followed by R. tanezumi (37.4%), R. nitidus (2.5%), and R. germaini (1.8%). R. korodentsensis and R. argentiverter constituted the remaining rodents, accounting for 2.2% of the total. The real-time PCR analysis revealed that 27 blood samples out of the 396 rodent samples collected, tested positive for Rickettsia (6.81%). R. germaini was shown to have the highest positive rate 1/8 (12.5%), followed by R. nitidus 1/10 (10.0%), R. tanezumi 14/149 (9.5%), and R. norvegicus 11/222 (4.9%). No other tick-borne pathogens were detected in any of the provinces. Sequencing of the positive samples as regards the ompB and 17kDa genes revealed the closest relation to R. felis. These findings highlight the potentially high risk of R. felis infection in humans and animals within the studied areas.

Sequences Related to Chimay Rhabdovirus Are Widely Distributed in Ixodes ricinus Ticks across England and Wales.

Ticks are the main arthropod vector of pathogens to humans and livestock in the British Isles. Despite their role as a vector of disease, many aspects of tick biology, ecology, and microbial association are poorly understood. To address this, we investigated the composition of the microbiome of adult and nymphal Ixodes ricinus ticks. The ticks were collected on a dairy farm in Southwest England and RNA extracted for whole genome sequencing. Sequences were detected from a range of microorganisms, particularly tick-associated viruses, bacteria, and nematodes. A majority of the viruses were attributed to phlebo-like and nairo-like virus groups, demonstrating a high degree of homology with the sequences present in I. ricinus from mainland Europe. A virus sharing a high sequence identity with Chimay rhabdovirus, previously identified in ticks from Belgium, was detected. Further investigations of I. ricinus ticks collected from additional sites in England and Wales also identified Chimay rhabdovirus viral RNA with varying prevalence in all tick populations. This suggests that Chimay rhabdovirus has a wide distribution and highlights the need for an extended exploration of the tick microbiome in the United Kingdom (UK).

Compendium: Management of Viral Hemorrhagic Fever (Viral Fever), Involving Its Pathogenesis

The term "Viral Hemorrhagic Fever" (VHF) describes a severe feverish sickness characterized by aberrant vascular control, vascular damage, and hemorrhagic symptoms. Multiple viruses belonging to distinct families are the cause of this illness. The viruses that cause VHF are categorized into seven distinct families according to the International Committee on Taxonomy of Viruses' most recent classification: Hantaviridae, Nairoviridae, Filoviridae, Phenuiviridae, Paramyxoviridae, Arenavidae, and Flaviviridae are the families involved. The concept of virus hemorrhagic fevers (VHFs) originated in the 1930s when Soviet researchers were studying hantaviral hemorrhagic fever (HF) with renal dysfunction. Dengue fever/Dengue haemorrhagic fever and Kyasanur forest sickness are the two most common viral hemorrhagic fevers (VHF) in India that are transmitted by arthropod vectors. The diagnosis of community-acquired pneumonia (CCHF) in India is greatly hampered by the co-occurring symptoms of hemorrhagic fevers such as dengue, Kyasanur forest sickness, Hantavirus hemorrhagic fever, and other illnesses such as leptospirosis, meningococcal infections, and malaria. The pathophysiology, aetiology, diagnosis, treatment, symptoms, and indicators of virus hemorrhagic fevers (VHFs) are all covered in this review article.

The Adaptive Immune Response against Bunyavirales.

The Bunyavirales order includes at least fourteen families with diverse but related viruses, which are transmitted to vertebrate hosts by arthropod or rodent vectors. These viruses are responsible for an increasing number of outbreaks worldwide and represent a threat to public health. Infection in humans can be asymptomatic, or it may present with a range of conditions from a mild, febrile illness to severe hemorrhagic syndromes and/or neurological complications. There is a need to develop safe and effective vaccines, a process requiring better understanding of the adaptive immune responses involved during infection. This review highlights the most recent findings regarding T cell and antibody responses to the five Bunyavirales families with known human pathogens (Peribunyaviridae, Phenuiviridae, Hantaviridae, Nairoviridae, and Arenaviridae). Future studies that define and characterize mechanistic correlates of protection against Bunyavirales infections or disease will help inform the development of effective vaccines.

Species-level Microbiota of Biting Midges and Ticks from Poyang Lake.

The purpose of this study was to investigate the bacterial communities of biting midges and ticks collected from three sites in the Poyang Lake area, namely, Qunlu Practice Base, Peach Blossom Garden, and Huangtong Animal Husbandry, and whether vectors carry any bacterial pathogens that may cause diseases to humans, to provide scientific basis for prospective pathogen discovery and disease prevention and control. Using a metataxonomics approach in concert with full-length 16S rRNA gene sequencing and operational phylogenetic unit (OPU) analysis, we characterized the species-level microbial community structure of two important vector species, biting midges and ticks, including 33 arthropod samples comprising 3,885 individuals, collected around Poyang Lake. A total of 662 OPUs were classified in biting midges, including 195 known species and 373 potentially new species, and 618 OPUs were classified in ticks, including 217 known species and 326 potentially new species. Surprisingly, OPUs with potentially pathogenicity were detected in both arthropod vectors, with 66 known species of biting midges reported to carry potential pathogens, including Asaia lannensis and Rickettsia bellii, compared to 50 in ticks, such as Acinetobacter lwoffii and Staphylococcus sciuri. We found that Proteobacteria was the most dominant group in both midges and ticks. Furthermore, the outcomes demonstrated that the microbiota of midges and ticks tend to be governed by a few highly abundant bacteria. Pantoea sp7 was predominant in biting midges, while Coxiella sp1 was enriched in ticks. Meanwhile, Coxiella spp., which may be essential for the survival of Haemaphysalis longicornis Neumann, were detected in all tick samples. The identification of dominant species and pathogens of biting midges and ticks in this study serves to broaden our knowledge associated to microbes of arthropod vectors. Biting midges and ticks carry large numbers of known and potentially novel bacteria, and carry a wide range of potentially pathogenic bacteria, which may pose a risk of infection to humans and animals. The microbial communities of midges and ticks tend to be dominated by a few highly abundant bacteria.

Impacts of Changing Climate on Arthropod Vectors and Diseases Transmission

Climate change stands as a burgeoning global concern with profound implications. The present review seeks to present the projected impacts of climate change on disease vectors and their transmission of various human and animal diseases. The impact of climate on the prevalence of vector-borne diseases (VBDs), which significantly affect human and animal populations, is notable. The occurrence of VBDs, influenced by local epidemiological and ecological factors alongside specific climatic conditions, may exhibit fluctuations due to climate change. Particularly affected are exothermic arthropod vectors, responsible for transmitting most vectorborne diseases. The intricate interplay of temperature, precipitation, humidity, and other environmental factors significantly shapes the reproduction, development, behavior, and population dynamics of arthropod disease vectors. Also, climate change can alter the spread of pathogens within vectors, influence population dynamics, and impact the range of nonhuman vertebrate reservoirs for numerous vector-borne diseases. Predicting the precise impact of sustained climate change on these diseases poses a considerable challenge, necessitating comprehensive long-term research. These researches must encompass the effects of climate change while considering the contributions of other global change agents, including increased trade and travel, demographic shifts, civil unrests, alterations in land use, water availability, and related factors. The association between climate change and the emergence of specific diseases has been established. However, for certain diseases, the risk of local transmission is significant, while for others, pinpointing the exact influence remains elusive. Therefore, strategic adaptation and preparedness for the shifting distribution patterns of VBDs are imperative, especially in the context of Nigeria and Africa as a whole.

Subolesin knockdown in tick cells provides insights into vaccine protective mechanisms

Ticks as obligate blood-feeding arthropod vectors of pathogenic viruses, bacteria, protozoa and helminths associated with prevalent tick-borne diseases (TBDs) worldwide. These arthropods constitute the second vector after mosquitoes that transmit pathogens to humans and the first vector in domestic animals. Vaccines constitute the safest and more effective approach to control tick infestations and TBDs, but research is needed to identify new antigens and improve vaccine formulations. The tick protein Subolesin (Sub) is a well-known vaccine protective antigen with a highly conserved sequence at both gene and protein levels in the Ixodidae and among arthropods and vertebrates. In this study, transcriptomics and proteomics analyses were conducted together with graph theory data analysis in wild type and Sub knockdown (KD) tick ISE6 cells in order to identify and characterize the functional implications of Sub in tick cells. The results support a key role for Sub in the regulation of gene expression in ticks and the relevance of this antigen in vaccine development against ticks and TBDs. Proteins with differential representation in response to Sub KD provide insights into vaccine protective mechanisms and candidate tick protective antigens.

To the 55th аnniversary of the Department of Virus Ecology with the Scientific and Practical Center for the Ecology and Epidemiology of Influenza (D.I. Ivanovsky Institute of Virology of the N.F. Gamaleya National Research Center for Epidemiology and Microbiology of the Ministry of Health of Russian Federation)

The article presents historical aspects and key achievements of the Department of Virus Ecology (DVE) with the Scientific and Practical Center for Influenza Ecology and Epidemiology, which was established in 1969 at the D.I. Ivanovsky Institute of Virology of Academy of Medical Sciences of the USSR. For over 50 years, the DVE has been devoted to addressing fundamental issues in virus ecology, including the formation of viral populations in nature, and conducting comprehensive large-scale studies in the interest of the state’s biosecurity. The department’s primary focus is on particularly dangerous (arboviral) and socially significant (influenza and other acute respiratory viral infections, parenteral hepatitis) viral infections. As a result of this extensive work in the Northern Eurasia region, over 2,000 strains of zoonotic viruses (17 genera, 8 families), ecologically linked to various arthropod vectors and vertebrate hosts, have been isolated. Many of them have been registered in international catalogs as new species. The role of these isolated viruses in human pathology has been studied, new viral infections have been described, and diagnostic preparations have been developed. The scientific results obtained by the department are of high priority and internationally recognized.

Current diagnostics and biomarkers for arboviral infections (a review on Dengue, Zika, West Nile and Chikungunya viruses)

Arboviral infections, transmitted to humans primarily through arthropod vectors, constitute a significant global health threat. Arboviruses, such as Dengue, Zika, Chikungunya, and West Nile viruses, continue to cause widespread outbreaks, necessitating advanced diagnostic tools. Emerging technologies including Lab On A Chip (LOC), Lab On A Disc (LOAD), Microfluidic Paper-Based Analytical Devices (µPADS), Lateral Flow Devices, CRISPR-CAS 12/13, Quartz crystal microbalance (QCM), and Nano-Technology are evaluated for their potential to enhance arboviral diagnosis, offering rapid, accurate, and point-of-care solutions. Furthermore, the identification of robust biomarkers, including Inflammatory Cytokines, Antibodies, Endothelial Activation Products and Indicators of Tissue or Organ Damage, is crucial for improving the understanding of disease pathogenesis, prognosis, and treatment response. A comprehensive analysis of potential diagnostics and biomarkers for arboviral infections sheds light on the evolving strategies to combat these medically significant diseases, ultimately contributing to more effective surveillance, diagnosis and management worldwide.

Tularemia on the rise in Switzerland? A one health approach is needed!

In the last 10years, an increase intularemiacases has been observed in both humans and animals in Switzerland.In these, infection with Francisella tularensis, the causative agent of the zoonotic disease tularemia, can occurthrough arthropodvectors or contact to infected animals or exposure to contaminated environmental sources. Currently,we are only able to postulatepotentialaetiologies: (i)behavioralchanges of humans with more exposure to endemic habitats of infected arthropod vectors; (ii) an increased rate of tularemia infected ticks; (iii) increasing numberand geographical regionsof tick biotopes; (iv) increasing and/or more diverse reservoir populations; (v) increasing presence ofbacteriain the environment; (vi) raised awarenessand increased testingamong physicians; (vii) improved laboratory techniques includingmolecular testing. To approach these questions, a one-health strategy is necessary. A functioningcollaboration between public health, human medicine, and diagnostic and veterinary units for the control oftularemiamust be established.Furthermore,the public should be includedwithin citizen-supported-science-projects.

The Perpetual Vector Mosquito Threat and Its Eco-Friendly Nemeses.

Mosquitoes are the most notorious arthropod vectors of viral and parasitic diseases for which approximately half the world's population, ~4,000,000,000, is at risk. Integrated pest management programs (IPMPs) have achieved some success in mitigating the regional transmission and persistence of these diseases. However, as many vector-borne diseases remain pervasive, it is obvious that IPMP successes have not been absolute in eradicating the threat imposed by mosquitoes. Moreover, the expanding mosquito geographic ranges caused by factors related to climate change and globalization (travel, trade, and migration), and the evolution of resistance to synthetic pesticides, present ongoing challenges to reducing or eliminating the local and global burden of these diseases, especially in economically and medically disadvantaged societies. Abatement strategies include the control of vector populations with synthetic pesticides and eco-friendly technologies. These "green" technologies include SIT, IIT, RIDL, CRISPR/Cas9 gene drive, and biological control that specifically targets the aquatic larval stages of mosquitoes. Regarding the latter, the most effective continues to be the widespread use of Lysinibacillus sphaericus (Ls) and Bacillus thuringiensis subsp. israelensis (Bti). Here, we present a review of the health issues elicited by vector mosquitoes, control strategies, and lastly, focus on the biology of Ls and Bti, with an emphasis on the latter, to which no resistance has been observed in the field.

Research on arthropod vectors of plant pathogens in a post-Subsection Cc world: current status and future prospects

Abstract The study of herbivorous arthropod vectors of plant pathogens has been a subdiscipline within entomology for more than a century. It was recognized as a unique field with the establishment of a Subsection (Cc) in the Entomological Society of America (ESA) from 1953 through 2007. During that period, work in the field expanded from an initial emphasis on management of vector-borne plant pathogens to include biology of the pathosystems. Since 2007, when ESA reorganized the subsections within the society, work on herbivorous vectors of plant pathogens has continued to grow. This article briefly summarizes the work in this field prior to, during, and after the ESA Subsection Cc era. We identify and describe 4 research areas that have characterized the field since 2007: Molecular mechanisms of vector–plant interactions, managing vectors and pathogen transmission in agriculture, illuminating the ecology of vectors and pathogens outside of crops, and pathogen manipulation of host phenotypes and vector behavior. We then identify 10 frontiers and prospects for the field in the coming years that build on these 4 research areas, ranging from molecular and cellular aspects to ramifications for managed and natural ecosystems. We also examine trends in funding and professional opportunities for scientists working on herbivorous vectors and pathogens. Finally, we renew the call for greater integration of work addressing vector-borne plant, animal, and human pathogens due to fundamental similarities in their biology and importance for human well-being within an expanded understanding of the “One Health” paradigm, which currently emphasizes human and animal health.

Cat Flea Coinfection with Rickettsia felis and Rickettsia typhi.

Purpose: Flea-borne rickettsioses, collectively referred to as a term for etiological agents Rickettsia felis, Rickettsia typhi, and RFLOs (R. felis-like organisms), has become a public health concern around the world, specifically in the United States. Due to a shared arthropod vector (the cat flea) and clinical signs, discriminating between Rickettsia species has proven difficult. While the effects of microbial coinfections in the vector can result in antagonistic or synergistic interrelationships, subsequently altering potential human exposure and disease, the impact of bacterial interactions within flea populations remains poorly defined. Methods: In this study, in vitro and in vivo systems were utilized to assess rickettsial interactions in arthropods. Results: Coinfection of both R. felis and R. typhi within a tick-derived cell line indicated that the two species could infect the same cell, but distinct growth kinetics led to reduced R. felis growth over time, regardless of infection order. Sequential flea coinfections revealed the vector could acquire both Rickettsia spp. and sustain coinfection for up to 2 weeks, but rickettsial loads in coinfected fleas and feces were altered during coinfection. Conclusion: Altered rickettsial loads during coinfection suggest R. felis and R. typhi interactions may enhance the transmission potential of either agent. Thus, this study provides a functional foundation to disentangle transmission events propelled by complex interspecies relationships during vector coinfections.

The role of Rab27 in tick extracellular vesicle biogenesis and pathogen infection

BackgroundThe blacklegged tick, Ixodes scapularis, transmits most vector-borne diseases in the US. It vectors seven pathogens of public health relevance, including the emerging human pathogen Anaplasma phagocytophilum. Nevertheless, it remains critically understudied compared to other arthropod vectors. Ixodes scapularis releases a variety of molecules that assist in the modulation of host responses. Recently, it was found that extracellular vesicles (EVs) carry several of these molecules and may impact microbial transmission to the mammalian host. EV biogenesis has been studied in mammalian systems and is relatively well understood, but the molecular players important for the formation and secretion of EVs in arthropods of public health relevance remain elusive. RabGTPases are among the major molecular players in mammalian EV biogenesis. They influence membrane identity and vesicle budding, uncoating, and motility.MethodsUsing BLAST, an in silico pathway for EV biogenesis in ticks was re-constructed. We identified Rab27 for further study. EVs were collected from ISE6 tick cells after knocking down rab27 to examine its role in tick EV biogenesis. Ixodes scapularis nymphs were injected with small interfering RNAs to knock down rab27 and then fed on naïve and A. phagocytophilum-infected mice to explore the importance of rab27 in tick feeding and bacterial acquisition.ResultsOur BLAST analysis identified several of the proteins involved in EV biogenesis in ticks, including Rab27. We show that silencing rab27 in I. scapularis impacts tick fitness. Additionally, ticks acquire less A. phagocytophilum after rab27 silencing. Experiments in the tick ISE6 cell line show that silencing of rab27 causes a distinct range profile of tick EVs, indicating that Rab27 is needed to regulate EV biogenesis.ConclusionsRab27 is needed for successful tick feeding and may be important for acquiring A. phagocytophilum during a blood meal. Additionally, silencing rab27 in tick cells results in a shift of extracellular vesicle size. Overall, we have observed that Rab27 plays a key role in tick EV biogenesis and the tripartite interactions among the vector, the mammalian host, and a microbe it encounters.Graphical

Detection of Brucella in Dermacentor Ticks of Wild Boar with Brucellosis

Brucellosis is a sanitary and economically relevant disease affecting humans, livestock, and wildlife. Ticks have been suggested as vectors, long-term carriers, and amplifiers of Brucella. In this study, ticks from wildlife ungulate hosts living in hunting reserves of a central region of Spain were collected during a 6-year period, pooled, and screened for Brucella spp. by PCR. Aiming to correlate Brucella spp. DNA presence in ticks with Brucella spp. infections in wildlife ungulate hosts, liver samples from deceased wildlife ungulates coming from the hunting reserves showing a positive result for Brucella in ticks were tested using a commercial ELISA. In total, 229 tick pools from wild boar (Sus scrofa, n = 176; 76.8%, 95% CI 70.9%–81.8%), red deer (Cervus elaphus, n = 40; 17.4%, 95% CI 13.1%–22.9%), mouflon (Ovis orientalis musimon, n = 7; 3.06%, 95% CI 1.49%–6.17%), and fallow deer (Dama dama, n = 6; 2.62%, 95% CI 1.21%–5.60%) were analyzed. PCR results showed that 3.93% (95% CI 2.08%–7.30%) tick pools (9/229) from 16.6% hunting reserves (7/41) screened yielded a positive PCR result for Brucella. All positive ticks were Dermacentor (Dermacentor marginatus or Dermacentor reticulatus) collected from wild boar. Ticks collected from wild boars were positive to Brucella in a relative percentage of 5.10% (95% CI = 1.61–11.4) in 2018 and of 7.59% (95% CI = 2.79–15.6) in 2021 (6-year prevalence of 5.17%, 9/176). ELISA showed positive results in three wild boars coming from two out of seven hunting reserves (28.5%) with a positive PCR for Brucella in ticks. To conclude, Brucella spp. DNA can be detected in Dermacentor ticks parasitizing wild boars living in hunting reserves harboring Brucella spp.-seropositive wild boars. This study provides evidence that the contribution of arthropod vectors should be considered in the epidemiology of brucellosis in wildlife.