RESUMO
Flaviviruses such as dengue virus (DENV), Zika virus (ZIKV), and yellow fever virus (YFV) are spread by mosquitoes and cause human disease and mortality in tropical areas. In contrast, Powassan virus (POWV), which causes severe neurologic illness, is a flavivirus transmitted by ticks in temperate regions of the Northern hemisphere. We find serologic neutralizing activity against POWV in individuals living in Mexico and Brazil. Monoclonal antibodies P002 and P003, which were derived from a resident of Mexico (where POWV is not reported), neutralize POWV lineage I by recognizing an epitope on the virus envelope domain III (EDIII) that is shared with a broad range of tick- and mosquito-borne flaviviruses. Our findings raise the possibility that POWV, or a flavivirus closely related to it, infects humans in the tropics.
Assuntos
Anticorpos Neutralizantes , Humanos , Brasil , Anticorpos Neutralizantes/imunologia , México , Anticorpos Antivirais/imunologia , Animais , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Flavivirus/imunologia , Epitopos/imunologia , Anticorpos Monoclonais/imunologia , Carrapatos/virologia , Carrapatos/imunologia , Feminino , MasculinoRESUMO
A peptide from the P0 acidic ribosomal protein (pP0) of ticks conjugated to keyhole limpet hemocyanin from Megathura crenulata has shown to be effective against different tick species when used in host vaccination. Turning this peptide into a commercial anti-tick vaccine will depend on finding the appropriate, technically and economically feasible way to present it to the host immune system. Two conjugates (p64K-Cys1pP0 and p64K-ßAla1pP0) were synthesized using the p64K carrier protein from Neisseria meningitidis produced in Escherichia coli, the same cross-linking reagent, and two analogues of pP0. The SDS-PAGE analysis of p64K-Cys1pP0 showed a heterogeneous conjugate compared to p64K-ßAla1pP0 that was detected as a protein band at 91kDa. The pP0/p64K ratio determined by MALDI-MS for p64K-Cys1pP0 ranged from 1 to 8, being 3-5 the predominant ratio, while in the case of p64K-ßAla1pP0 this ratio was 5-7. Cys1pP0 was partially linked to 35 out of 39 Lys residues and the N-terminal end, while ßAla1pP0 was mostly linked to the six free cysteine residues, to the N-terminal end, and, in a lesser extent, to Lys residues. The assignment of the conjugation sites and side reactions were based on the identification of type 2 peptides. Rabbit immunizations showed the best anti-pP0 titers and the highest efficacy against Rhipicephalus sanguineus ticks when the p64K-Cys1pP0 was used as vaccine antigen. The presence of high molecular mass aggregates observed in the SDS-PAGE analysis of p64K-Cys1pP0 could be responsible for a better immune response against pP0 and consequently for its better efficacy as an anti-tick vaccine. Graphical abstract.
Assuntos
Proteínas da Membrana Bacteriana Externa/imunologia , Cromatografia Líquida/métodos , Neisseria meningitidis/imunologia , Espectrometria de Massas em Tandem/métodos , Carrapatos/imunologia , Vacinas/imunologia , Animais , Eletroforese em Gel de Poliacrilamida , Hemocianinas/imunologia , Coelhos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodosRESUMO
Ticks are ectoparasitic arthropods that necessarily feed on the blood of their vertebrate hosts. The success of blood acquisition depends on the pharmacological properties of tick saliva, which is injected into the host during tick feeding. Saliva is also used as a vehicle by several types of pathogens to be transmitted to the host, making ticks versatile vectors of several diseases for humans and other animals. When a tick feeds on an infected host, the pathogen reaches the gut of the tick and must migrate to its salivary glands via hemolymph to be successfully transmitted to a subsequent host during the next stage of feeding. In addition, some pathogens can colonize the ovaries of the tick and be transovarially transmitted to progeny. The tick immune system, as well as the immune system of other invertebrates, is more rudimentary than the immune system of vertebrates, presenting only innate immune responses. Although simpler, the large number of tick species evidences the efficiency of their immune system. The factors of their immune system act in each tick organ that interacts with pathogens; therefore, these factors are potential targets for the development of new strategies for the control of ticks and tick-borne diseases. The objective of this review is to present the prevailing knowledge on the tick immune system and to discuss the challenges of studying tick immunity, especially regarding the gaps and interconnections. To this end, we use a comparative approach of the tick immune system with the immune system of other invertebrates, focusing on various components of humoral and cellular immunity, such as signaling pathways, antimicrobial peptides, redox metabolism, complement-like molecules and regulated cell death. In addition, the role of tick microbiota in vector competence is also discussed.
Assuntos
Imunidade Celular , Imunidade Humoral , Saliva/imunologia , Glândulas Salivares/imunologia , Doenças Transmitidas por Carrapatos/imunologia , Carrapatos/imunologia , Animais , Interações Hospedeiro-Parasita , Humanos , Saliva/metabolismo , Glândulas Salivares/metabolismo , Doenças Transmitidas por Carrapatos/metabolismo , Doenças Transmitidas por Carrapatos/transmissão , Carrapatos/metabolismoRESUMO
Introduction: Ticks are hematophagous ectoparasites that cause significate economical losses. Acaricide application is themain method to tick control. However, it causes environmental contamination and selects resistant ticks. The immunological control represents a suitable method to replace or complement acaricide application. During its life cycle, female ticksingest large amounts of blood, which contains toxic components able to damage biomolecules. Understanding which molecular mechanisms and proteins are involved in avoid damages caused by blood intake in ticks and other hematophagousarthropods could help to found potential candidate antigens to compose an anti-tick vaccine.Review: Hemoglobin comprises almost 20% of mammalian blood proteins, its hydrolysis during tick digestion increasestotal free heme that can potentially generate reactive oxygen species (ROS), which easily oxidize lipids, proteins and DNA,modifying they structure and function. Lipids are more susceptible to high ROS levels. It can lead to membrane instabilityand cell death. Protein modifications caused by ROS can promote the protein loss of function and cell disturbance, however,it can also work as post-translational modifications, acting in cell signaling processes. DNA presents more efficient protective mechanisms against ROS, but damages can lead to double helix rupture. Oxidative stress is defined as a disturbance inthe balance between the production and elimination of ROS, in favor of ROS production, leading to a disruption in redoxhomeostasis and/or molecular damage. Despite the well-recognized heme oxidative power and its already demonstratedcytotoxicity, ticks are able to feed on blood, controlling the redox homeostasis without causing oxidative stress. This occurs because ticks developed physiological adaptations to transport, store, metabolize and secrete toxic components fromthe diet. The strategies, such as heme compartmentalization in specialized organelles...(AU)
Assuntos
Animais , Homeostase , Carrapatos/imunologia , Estresse Oxidativo , Espécies Reativas de Oxigênio , Comportamento de Busca por HospedeiroRESUMO
BACKGROUND: Rickettsia bacteria are responsible for diseases in humans and animals around the world, however few details are available regarding its ecology and circulation among wild animals and human populations at high transmission risk in Brazil. The aim of this study was to investigate the occurrence of ticks and Rickettsia spp. in wild boars, corresponding hunting dogs and hunters. METHODS: Serum samples and ticks were collected from 80 free-range wild boars, 170 hunting dogs and 34 hunters from southern and central-western Brazil, from the Atlantic Forest and Cerrado biomes, respectively, between 2016 and 2018. Serum samples were tested by indirect immunofluorescent-antibody assay (IFA) to detect IgG antibodies against Rickettsia rickettsii, Rickettsia parkeri, Rickettsia bellii, Rickettsia rhipicephali and Rickettsia amblyommatis. Tick species were identified by morphological taxonomic keys, as previously described. A total of 164 ticks including A. sculptum, A. brasiliense and A. aureolatum were tested in PCR assays for Spotted Fever Group (SFG) Rickettsia spp. RESULTS: A total of 58/80 (72.5%) wild boars, 24/170 (14.1%) hunting dogs and 5/34 (14.7%) hunters were positive (titers ≥ 64) to at least one Rickettsia species. A total of 669/1,584 (42.2%) ticks from wild boars were identified as Amblyomma sculptum, 910/1,584 (57.4%) as Amblyomma brasiliense, 4/1,584(0.24%) larvae of Amblyomma spp. and 1/1,584 (0.06%) nymph as Amblyolmma dubitatum. All 9 ticks found on hunting dogs were identified as Amblyomma aureolatum and all 22 ticks on hunters as A. sculptum. No tested tick was positive by standard PCR to SFG Rickettsia spp. CONCLUSIONS: The present study was the concomitant report of wild boar, hunting dog and hunter exposure to SFG rickettsiae agents, performed in two different Brazilian biomes. Wild boar hunting may increase the risk of human exposure and consequently tick-borne disease Wild boars may be carrying and spreading capybara ticks from their original habitats to other ecosystems. Further studies can be required to explore the ability of wild boars to infecting ticks and be part of transmission cycle of Rickettsia spp.
Assuntos
Anticorpos Antibacterianos/sangue , Doenças do Cão/sangue , Cães/sangue , Infecções por Rickettsia/sangue , Infecções por Rickettsia/veterinária , Rickettsia/imunologia , Doenças dos Suínos/sangue , Carrapatos/imunologia , Animais , Animais Selvagens/sangue , Animais Selvagens/microbiologia , Brasil , Doenças do Cão/microbiologia , Cães/microbiologia , Feminino , Humanos , Masculino , Rickettsia/classificação , Rickettsia/isolamento & purificação , Infecções por Rickettsia/microbiologia , Sus scrofa/sangue , Sus scrofa/microbiologia , Suínos , Doenças dos Suínos/microbiologia , Carrapatos/classificação , Carrapatos/microbiologiaRESUMO
Cocktail vaccines are proposed as an attractive way to increase protection efficacy against specific tick species. Furthermore, such vaccines made with different tick antigens have the potential of cross-protecting against a broad range of tick species. However, there are still limitations to the selection of immunogen candidates. Acknowledging that glutathione S-transferases (GSTs) have been exploited as vaccines against ticks and other parasites, this study aimed to analyze a GST-cocktail vaccine as a potential broad-spectrum tick vaccine. To constitute the GST-cocktail vaccine, five tick species of economic importance for livestock industry were studied (Rhipicephalus appendiculatus, Rhipicephalus decoloratus, Rhipicephalus microplus, Amblyomma variegatum, and Haemaphysalis longicornis). Tick GST ORF sequences were cloned, and the recombinant GSTs were produced in Escherichia coli. rGSTs were purified and inoculated into rabbits, and the immunological response was characterized. The humoral response against rGST-Rd and rGST-Av showed a stronger cross-reactivity against heterologous rGSTs compared to rGST-Hl, rGST-Ra, and rGST-Rm. Therefore, rGST-Rd and rGST-Av were selected for constituting an experimental rGST-cocktail vaccine. Vaccination experiment in rabbits showed that rGST-cocktail caused 35% reduction in female numbers in a Rhipicephalus sanguineus infestation. This study brings forward an approach to selecting immunogens for cocktail vaccines, and the results highlight rGST-Rd and rGST-Av as potentially useful tools for the development of a broad-spectrum tick vaccine.
Assuntos
Glutationa Transferase/imunologia , Infestações por Carrapato/prevenção & controle , Carrapatos/enzimologia , Carrapatos/imunologia , Vacinas/imunologia , Animais , Reações Cruzadas/imunologia , Glutationa Transferase/química , Glutationa Transferase/genética , Fases de Leitura Aberta , Coelhos , Rhipicephalus sanguineus/enzimologia , Rhipicephalus sanguineus/imunologia , Vacinas/administração & dosagemRESUMO
Introduction: Ticks are hematophagous ectoparasites that cause significate economical losses. Acaricide application is themain method to tick control. However, it causes environmental contamination and selects resistant ticks. The immunological control represents a suitable method to replace or complement acaricide application. During its life cycle, female ticksingest large amounts of blood, which contains toxic components able to damage biomolecules. Understanding which molecular mechanisms and proteins are involved in avoid damages caused by blood intake in ticks and other hematophagousarthropods could help to found potential candidate antigens to compose an anti-tick vaccine.Review: Hemoglobin comprises almost 20% of mammalian blood proteins, its hydrolysis during tick digestion increasestotal free heme that can potentially generate reactive oxygen species (ROS), which easily oxidize lipids, proteins and DNA,modifying they structure and function. Lipids are more susceptible to high ROS levels. It can lead to membrane instabilityand cell death. Protein modifications caused by ROS can promote the protein loss of function and cell disturbance, however,it can also work as post-translational modifications, acting in cell signaling processes. DNA presents more efficient protective mechanisms against ROS, but damages can lead to double helix rupture. Oxidative stress is defined as a disturbance inthe balance between the production and elimination of ROS, in favor of ROS production, leading to a disruption in redoxhomeostasis and/or molecular damage. Despite the well-recognized heme oxidative power and its already demonstratedcytotoxicity, ticks are able to feed on blood, controlling the redox homeostasis without causing oxidative stress. This occurs because ticks developed physiological adaptations to transport, store, metabolize and secrete toxic components fromthe diet. The strategies, such as heme compartmentalization in specialized organelles...
Assuntos
Animais , Carrapatos/imunologia , Estresse Oxidativo , Homeostase , Comportamento de Busca por Hospedeiro , Espécies Reativas de OxigênioRESUMO
Ticks are responsible for the transmission of viral, bacterial, and protozoal diseases of man and animals and also produce significant economic losses to cattle industry. The use of acaricides constitutes a major component of integrated tick control strategies. However, this is accompanied by the selection of acaricide-resistant ticks and contamination of environment and milk and meat products with drug residues. These issues highlight the need for alternative approaches to control tick infestations and have triggered the search for tick protective antigens for vaccine development. Vaccination as a tick control method has been practiced since the introduction of TickGARD and Gavac that were developed using the midgut glycoprotein Bm86 as antigen. Gavac within integrated tick management systems has proven to reduce the number of acaricidal applications per year that are required to control some strains of R. microplus ticks in different geographical regions. Nevertheless, it has limited or no efficacy against other tick species. These issues have stimulated research for additional tick protective antigens with critical functions in the tick. This chapter presents methodologies for the design and test of molecules as antigens against ticks. Considerations about different methods for the tick control compared to the immunological methods, the desirable characteristics for an anti-tick vaccine and the obstacles encountered for developing this kind of vaccines are discussed. Detailed methodologies for the establishment of a biological model to test new molecules as immunogens against ticks and to perform challenge trials with this model are presented. General considerations in the efficacy calculation for any anti-tick vaccine are also discussed.
Assuntos
Carrapatos/imunologia , Vacinas/imunologia , Animais , Antígenos/imunologia , Bovinos , Feminino , Imunização , Masculino , Carrapatos/classificaçãoRESUMO
The anaphylaxis response is frequently associated with food allergies, representing a significant public health hazard. Recently, exposure to tick bites and production of specific IgE against α-galactosyl (α-Gal)-containing epitopes has been correlated to red meat allergy. However, this association and the source of terminal, non-reducing α-Gal-containing epitopes have not previously been established in Brazil. Here, we employed the α-1,3-galactosyltransferase knockout mouse (α1,3-GalT-KO) model and bacteriophage Qß-virus like particles (Qß-VLPs) displaying Galα1,3Galß1,4GlcNAc (Galα3LN) epitopes to investigate the presence of α-Gal-containing epitopes in the saliva of Amblyomma sculptum, a species of the Amblyomma cajennense complex, which represents the main tick that infests humans in Brazil. We confirmed that the α-1,3-galactosyltransferase knockout animals produce significant levels of anti-α-Gal antibodies against the Galα1,3Galß1,4GlcNAc epitopes displayed on Qß-virus like particles. The injection of A. sculptum saliva or exposure to feeding ticks was also found to induce both IgG and IgE anti-α-Gal antibodies in α-1,3-galactosyltransferase knockout mice, thus indicating the presence of α-Gal-containing epitopes in the tick saliva. The presence of α-Gal-containing epitopes was confirmed by ELISA and immunoblotting following removal of terminal α-Gal epitopes by α-galactosidase treatment. These results suggest for the first known time that bites from the A. sculptum tick may be associated with the unknown etiology of allergic reactions to red meat in Brazil.
Assuntos
Hipersensibilidade Alimentar/imunologia , Carne Vermelha/efeitos adversos , Saliva/imunologia , Carrapatos/imunologia , Animais , Brasil , Mapeamento de Epitopos , Epitopos/química , Epitopos/imunologia , Feminino , Hipersensibilidade Alimentar/etiologia , Galactosiltransferases/genética , Galactosiltransferases/imunologia , Humanos , Imunoglobulina E/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Carne Vermelha/análise , Saliva/química , Carrapatos/químicaRESUMO
As blood-sucking parasites, ticks inflict great damage to animals and humans in many parts of the world. The continued use of chemical acaricides is not sustainable due to increasing tick resistance, growing public concern over drug residues in food and in the environment, and the high cost of developing new acaricides. Therefore, an alternative control strategy is urgently needed. Vaccines against ticks have been shown to be functionally feasible, as highlighted by the success of Bm86 vaccines against Rhipicephalus (Boophilus) microplus and closely related tick species. However, a limited number of tick antigens with cross-protective epitopes have been characterized so far, limiting widespread deployment of the available vaccines, including those derived from Bm86. Therefore, identifying tick antigens with potential broad-spectrum protection against multiple tick species is subject of vigorous research at present. In this paper, progress towards effective anti-tick vaccines is reviewed in the light of emerging data from studies including heterologous tick challenge. Taken together, these studies indicate that the decades-long search for a universal tick vaccine is making progress, with such a vaccine likely to be based on multiple cross-reactive antigens.