Cattle Specific Immune Mechanisms used against the Protozoan Theileria annulata

Theileria annulata, the causative agent of tropical theileriosis, is an intracellular protozoan parasite transmitted by ticks of the genus Hyalomma. This tick-borne disease (TBD) exerts a high impact on livestock production in many developing tropical and subtropical countries. With an intricate life cycle and wide distribution around the world, many advances were made to restrict the impact and to control this TBD through the use of acaricides, chemotherapy and attenuated vaccines. However, an overreliance on these chemicals has meant new approaches for developing more effective vaccines are needed. Decades of studies support the idea that the humoral immune response elicited against the sporozoite stage of the tick life cycle may protect the host from infection. Further protective responses provided by cytotoxic T-cells, macrophages, and Natural Killer cells have also been identified as critically important during T. annulata infection. Here our focus will be the bovine immune response upon T. annulata infection, particularly the differential humoral and cellular immune responses. Our aim is to highlight the importance of the mechanisms potentially involved in protective immunity as well as significant findings, which may be incorporated into novel strategies for tropical theileriosis control.publishersversionpublishe

TickProVac: An insight into the Rhipicephalus sanguineus tick salivary gland proteome during Ehrlichia canis infection towards vaccine development

As carraças são reconhecidas como vectores de diversos agentes patogénicos responsáveis por doenças relevantes na medicina humana e animal. Erliquiose monocítica canina (EMC), causada pela bactéria Ehrlichia canis, é transmitida pela carraça Rhipicephalus sanguineus. O potencial zoonótico da EMC está bem documentado com relatos de infecções humanas em aumento permanente. A infestação por carraças e as doenças por elas transmitidas (DTCs) continuam a representar um sério problema devido à falta de profilaxias eficazes. É, portanto, imperativo adotar novas abordagens, nomeadamente a utilização de vacinas, para a redução de infestações por carraças e DTCs. Actualmente não existe vacina anti-R. sanguineus comercialmente disponível. De forma a solucionar esta lacuna, o objetivo principal do presente trabalho foi a caracterização de genes e proteínas que atuam na interface vector-agente patogénico na presença de infeção para compreender os mecanismos associados à transmissão de DTCs. Neste trabalho estão reportados genes e proteínas diferencialmente expressos obtidos a partir da análise transcriptómica e proteómica das glândulas salivares (GSs) de R. sanguineus durante a infeção com E. canis. Os níveis de expressão dos genes que codificam as proteínas serina carboxipeptidase (psc), proteína de choque térmico (phsrp20) e proibitina (prohib) foram investigados in vitro e in vivo, em amostras infectadas e não infectadas. Posteriormente, o silenciamento de genes foi realizado através de RNA de interferência (RNAi) para avaliar o efeito da sub-expressão de ferritina 1 na alimentação, desenvolvimento ovárico, oogénese e aquisição E. canis pela carraça. O mesmo foi efetuado para determinar o efeito da sub-expressão de psc, prohib e phsrp20 na invasão e multiplicação desta bactéria na linha celular IDE8 e em R. sanguineus. O péptido pPHSRP20, relacionado com o choque térmico, foi sintetizado para avaliar a sua imunogenicidade em ratos CD1. Os resultados mostraram que o silenciamento de ferritina 1 compromete a competência da carraça em se alimentar e provoca alterações morfológicas e histoquímicas nos ovários e oócitos. Os dados transcriptómicos e proteómicos demonstraram que as alterações da expressão génica e proteica estão principalmente relacionadas com processos proteicos celulares e metabólicos e com atividades catalíticas, muito provavelmente um reflexo de alterações de transcrição e tradução em resposta à presença de infecção. Em amostras infectadas verificou-se uma sub-expressão de phsrp20 e prohib em células IDE8 e de phsrp20 e psc nas GSs. Inversamente, os genes psc nas células IDE8 e prohib nas GSs estavam sobre-expressos. Apesar de se terem atingido níveis elevados de silenciamento, o seu efeito na biologia de E. canis não foi determinado devido a limitações moleculares. pPHSRP20 desencadeou uma resposta imunitária detectável e específica nos ratos CD1. Em geral, os resultados demonstraram que a presença de E. canis nas GSs desencadeia respostas celulares para regulação do stress, inflamação e rearranjo do citoesqueleto. A modulação desta maquinaria molecular pela bactéria poderá ser uma estratégia para lidar e escapar à resposta imunitária e para utilizar proteínas do vector necessárias à virulência. Através destes resultados esperou identificar-se potenciais antigénios de carraça que contribuam para o desenvolvimento de uma vacina anti-R. sanguineus e/ou bloqueadora da transmissão de agentes patogénicos.Ticks are recognised as potent vectors of disease-causing pathogens of medical and veterinary importance. Ehrlichia canis, the causative agent of canine monocytic ehrlichiosis (CME), is transmitted by the brown dog tick Rhipicephalus sanguineus and is acknowledged as a highly infectious disease. The zoonotic potential of CME is widely recognised with reports of human infections steadily increasing. Tick infestation and tick-borne diseases (TBDs) remain a serious and persistent veterinary health problem, due to the lack of efficient control measures. It is therefore vital that novel approaches to tackle TBDs are pursued. Although vaccination to reduce tick infestation is recognised, no anti- R. sanguineus vaccine exists. To address this, we aimed to characterise the crucial gene and protein interactions at the vector-pathogen interface to gain a fundamental understanding of the interactions underpinning disease transmission. Here we report differentially expressed genes and proteins found either in the literature or found in our transcriptomic and proteomic data from R. sanguineus salivary glands (SGs) during E. canis infection. The mRNA expression levels of the putative serine carboxypeptidase (psc), heat-shock related protein (phsrp20) and prohibitin-like protein genes were investigated in vitro and in vivo, in infected and uninfected samples. RNA interference (RNAi) was carried out to determine the effect of ferritin 1 in tick feeding, ovary (OV) development, oogenesis, and pathogen acquisition. We also determined the effect of a downregulation of three selected genes or proteins from our omics data on E. canis invasion and multiplication in the IDE8 tick cell line and R. sanguineus ticks. We synthesised a heat-shock related protein (pPHSRP20) peptide to evaluate its immunogenicity in CD1 mice. Our results have shown that silencing ferritin 1 alters tick competence to normally engorge and causes morphological and histochemical changes in the OV and oocytes. Our transcriptomic and proteomic data has revealed alterations in gene and protein expression, mostly concerning protein cellular and metabolic processes and catalytic activities, perhaps related with transcriptional and translational responses to E. canis infection. When analysing the transcription levels in E. canis-infected samples, a downregulation was verified for phsrp20 and prohib in IDE8 cells and phsrp20 and psc in the SGs, whereas an upregulation was observed for psc in IDE8 cells and prohib for the SGs. Even with high levels of gene silencing, the effect of gene silencing in E. canis biology was not determined due to molecular limitations. pPHSRP20 triggered a detectable and specific immune response in mice. Overall, results show that the presence of E. canis in the SGs leads to regulation of stress response, inflammation and cytoskeletal rearrangement molecules. Modulation of tick molecular machinery is a coping strategy to evade the host immune response and to utilise its proteins for infectivity. From this, we expected to identify tick antigens that will direct the development of an anti-R. sanguineus and/or transmission-blocking vaccine

An overview

Human diseases caused by protozoan parasites are renowned for their high rates of morbidity and mortality worldwide. Some examples include African trypanosomiasis or sleeping sickness, American trypanosomiasis or Chagas disease, leishmaniases, malaria and babesiosis. These infections tend to follow a chronic rather than an acute course with lifelong persistence of parasites. Regulatory T cells (Treg), in particular the CD4+CD25+ cell subset, appear to control the immune competence of host response triggered by the presence of parasites, promoting homeostasis and protecting the host from collateral tissue damage whilst allowing parasite persistence. To date, there is still considerable controversy on the characteristics and function of these cells when induced during diferente protozoan infections, evidencing the need of further research. Therefore, this review aims to provide a comprehensive overview about Treg cells development, phenotype determination and general functions. The above pathologies were used as selected examples to discuss the role of Treg cells during protozoan infections. Understanding of the mechanisms that contribute towards homeostasis and the survival of the host, and simultaneously allow the persistence of the pathogen, may yield important insights for new strategies of prophylaxis and therapy .publishersversionpublishe

What Makes Your Dog Itch? Maybe It Is the Kennel Tick!

Once upon a time, in a backyard not very far from you, lived a dog named Rex with long fluffy and shiny hair. Rex really loved to play outside, especially with his best friend and owner Jack, a nine-year-old boy. On a perfect spring day, when it was not too cold or too hot, Jack and Rex went for a walk in a green park close by, and when they returned home Jack noticed that his loyal friend was very itchy and was scratching his ear a lot. His first thought was as follows: “Well, there must be some dirt in his ear! After so much rolling on the grass it is normal.” A few days later Jack saw that Rex was very unhappy and started wondering what was happening. He called his mother quickly and they both rushed to see Rex. “Mommy what’s that on Rex’s ear? It seems like a wart! Is Rex sick?” Then his mother said “Hopefully not! You know Jack, these little things are parasites called ticks and they can make Rex itch and feel uncomfortable. I am sure that if you learn more about such small and incredible creatures, you will be amazed because there is more to them than meets the eye…”publishersversionpublishe

Functional and Immunological Relevance of Anaplasma marginale Major Surface Protein 1a Sequence and Structural Analysis.

Bovine anaplasmosis is caused by cattle infection with the tick-borne bacterium, Anaplasma marginale. The major surface protein 1a (MSP1a) has been used as a genetic marker for identifying A. marginale strains based on N-terminal tandem repeats and a 5'-UTR microsatellite located in the msp1a gene. The MSP1a tandem repeats contain immune relevant elements and functional domains that bind to bovine erythrocytes and tick cells, thus providing information about the evolution of host-pathogen and vector-pathogen interactions. Here we propose one nomenclature for A. marginale strain classification based on MSP1a. All tandem repeats among A. marginale strains were classified and the amino acid variability/frequency in each position was determined. The sequence variation at immunodominant B cell epitopes was determined and the secondary (2D) structure of the tandem repeats was modeled. A total of 224 different strains of A. marginale were classified, showing 11 genotypes based on the 5'-UTR microsatellite and 193 different tandem repeats with high amino acid variability per position. Our results showed phylogenetic correlation between MSP1a sequence, secondary structure, B-cell epitope composition and tick transmissibility of A. marginale strains. The analysis of MSP1a sequences provides relevant information about the biology of A. marginale to design vaccines with a cross-protective capacity based on MSP1a B-cell epitopes

Transcriptome and proteome response of Rhipicephalus annulatus tick vector to Babesia bigemina infection

Funding Information: RHIBAB - PTDC/CVT/112050/2009 “Differential expression and functional characterization of tick (Rhipicephalus annulatus) genes in response to pathogen infection (B. bigemina).” SA is the recipient of a post-doctoral grant supported by FCT Funding Information: The authors would like to acknowledge Fundação para a Ciência e Tecnologia (FCT) for funds to GHTM – UID/Multi/04413/2013. Publisher Copyright: Copyright © 2019 Antunes, Couto, Ferrolho, Sanches, Merino Charrez, De la Cruz Hernández, Mazuz, Villar, Shkap, de la Fuente and Domingos. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.A system biology approach was used to gain insight into tick biology and interactions between vector and pathogen. Rhipicephalus annulatus is one of the main vectors of Babesia bigemina which has a massive impact on animal health. It is vital to obtain more information about this relationship, to better understand tick and pathogen biology, pathogen transmission dynamics, and new potential control approaches. In ticks, salivary glands (SGs) play a key role during pathogen infection and transmission. RNA sequencing obtained from uninfected and B. bigemina infected SGs obtained from fed female ticks resulted in 6823 and 6475 unigenes, respectively. From these, 360 unigenes were found to be differentially expressed (p < 0.05). Reversed phase liquid chromatography-mass spectrometry identified a total of 3679 tick proteins. Among them 406 were differently represented in response to Babesia infection. The omics data obtained suggested that Babesia infection lead to a reduction in the levels of mRNA and proteins (n = 237 transcripts, n = 212 proteins) when compared to uninfected controls. Integrated transcriptomics and proteomics datasets suggested a key role for stress response and apoptosis pathways in response to infection. Thus, six genes coding for GP80, death-associated protein kinase (DAPK-1), bax inhibitor-1 related (BI-1), heat shock protein (HSP), heat shock transcription factor (PHSTF), and queuine trna-ribosyltransferase (QtRibosyl) were selected and RNA interference (RNAi) performed. Gene silencing was obtained for all genes except phstf. Knockdown of gp80, dapk-1, and bi-1 led to a significant increase in Babesia infection levels while hsp and QtRibosyl knockdown resulted in a non-significant decrease of infection levels when compared to the respective controls. Gene knockdown did not affect tick survival, but engorged female weight and egg production were affected in the gp80, dapk-1, and QtRibosyl-silenced groups in comparison to controls. These results advanced our understanding of tick-Babesia molecular interactions, and suggested new tick antigens as putative targets for vaccination to control tick infestations and pathogen infection/transmission.publishersversionpublishe

uncovering differences during Ehrlichia canis infection

The tick vector Rhipicephalus sanguineus is established as a complex of closely related species with high veterinary-medical significance, in which the presence of different genetic, morphological, and biological traits has resulted in the recognition of different lineages within taxa. One of the most striking differences in the "temperate" and "tropical" lineages of R. sanguineus (s.l.) is the vector competence to Ehrlichia canis, suggesting that these ticks tolerate and react differently to pathogen infection. The present study addresses the SG and MG proteome of the R. sanguineus tropical and temperate lineages and compares their proteomic profile during E. canis infection. Batches of nymphs from the two lineages were allowed to feed on naïve and experimentally E. canis infected dogs and after molting, adults were dissected, and salivary glands and midgut tissues separated. Samples were screened for the presence of E. canis before proteomic analyses. The representation of the proteins identified in infected and non-infected tissues of each lineage was compared and gene ontology used for protein classification. Results highlight important differences in those proteomic profiles that added to previous reported genetic, biological, behavioral, and morphological differences, strengthening the hypothesis of the existence of two different species. Comparing infected and non-infected tissues, the results show that, while in midgut tissues the response to E. canis infection is similar in the salivary glands, the two lineages show a different pattern of protein representation. Focusing on the proteins found only in the infected condition, the data suggests that the cement cone produced during tick feeding may be implicated in pathogen infection. This study adds useful information to the debate on the controversial R. sanguineus systematic status, to the discussion related with the different vectorial competence occurring between the two lineages and identifies potential targets for efficient tick and tick-borne disease control.publishersversionpublishe