Browsing by Author "de la Fuente, J."
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- An insight into the transcriptome of Rhipicephalus bursa: differential gene expression upon feeding and in response to salivary glands infection with Babesia ovisPublication . Couto, J.; Antunes, S.; Ferrolho, J.; Santos, A.S.; Santos-Silva, M.M.; de la Fuente, J.; Domingos, A.Understanding the paradigm of the pathogen-tick-host triad remains an intricate issue. Basic research focusing on each one of these interplays is necessary to better comprehend this dynamic system. One of such complex association is the Babesia ovis, transmitted by the Rhipicephalus bursa ticks. B. ovis is an intra-erythrocytic protozoan parasite highly pathogenic parasite, causing severe infection in sheep. Pathogen and vector co-evolved and during infection a substantial molecular dialogue/interchanges takes place. The pathogen is adapted to both its hosts, and remarkably transovarial and transstadial transmissions are present in the vector. In ticks, the salivary glands (SG) play important role in both, feeding and pathogen interaction, being a vehicle for pathogen transmission and a barrier that they need to surpass.
- Guidelines for the Direct Detection of Anaplasma spp. in Diagnosis and Epidemiological StudiesPublication . Silaghi, C.; Santos, A.S.; Gomes, J.; Christova, I.; Matei, I.A.; Walder, G.; Domingos, A.; Bell-Sakyi, L.; Sprong, H.; von Loewenich, F.D.; Oteo, J.A.; de la Fuente, J.; Dumler, J.S.The genus Anaplasma (Rickettsiales: Anaplasmataceae) comprises obligate intracellular Gram-negative bacteria that are mainly transmitted by ticks, and currently includes six species: Anaplasma bovis, Anaplasma centrale, Anaplasma marginale, Anaplasma phagocytophilum, Anaplasma platys, and Anaplasma ovis. These have long been known as etiological agents of veterinary diseases that affect domestic and wild animals worldwide. A zoonotic role has been recognized for A. phagocytophilum, but other species can also be pathogenic for humans. Anaplasma infections are usually challenging to diagnose, clinically presenting with nonspecific symptoms that vary greatly depending on the agent involved, the affected host, and other factors such as immune status and coinfections. The substantial economic impact associated with livestock infection and the growing number of human cases along with the risk of transfusion-transmitted infections, determines the need for accurate laboratory tests. Because hosts are usually seronegative in the initial phase of infection and serological cross-reactions with several Anaplasma species are observed after seroconversion, direct tests are the best approach for both case definition and epidemiological studies. Blood samples are routinely used for Anaplasma spp. screening, but in persistently infected animals with intermittent or low-level bacteremia, other tissues might be useful. These guidelines have been developed as a direct outcome of the COST action TD1303 EURNEGVEC ("European Network of Neglected Vectors and Vector-Borne Diseases"). They review the direct laboratory tests (microscopy, nucleic acid-based detection and in vitro isolation) currently used for Anaplasma detection in ticks and vertebrates and their application.
- Rhipicephalus bursa Sialotranscriptomic Response to Blood Feeding and Babesia ovis Infection: Identification of Candidate Protective AntigensPublication . Antunes, S.; Couto, J.; Ferrolho, J.; Rodrigues, F.; Nobre, J.; Santos, A.S.; Santos-Silva, M.M.; de la Fuente, J.; Domingos, A.Ticks are among the most prevalent blood-feeding arthropods, and they act as vectors and reservoirs for numerous pathogens. Sialotranscriptomic characterizations of tick responses to blood feeding and pathogen infections can offer new insights into the molecular interplay occurring at the tick-host-pathogen interface. In the present study, we aimed to identify and characterize Rhipicephalus bursa salivary gland (SG) genes that were differentially expressed in response to blood feeding and Babesia ovis infection. Our experimental approach consisted of RNA sequencing of SG from three different tick samples, fed-infected, fed-uninfected, and unfed-uninfected, for characterization and inter-comparison. Overall, 7,272 expressed sequence tags (ESTs) were constructed from unfed-uninfected, 13,819 ESTs from fed-uninfected, and 15,292 ESTs from fed-infected ticks. Two catalogs of transcripts that were differentially expressed in response to blood feeding and B. ovis infection were produced. Four genes coding for a putative vitellogenin-3, lachesin, a glycine rich protein, and a secreted cement protein were selected for RNA interference functional studies. A reduction of 92, 65, and 51% was observed in vitellogenin-3, secreted cement, and lachesin mRNA levels in SG, respectively. The vitellogenin-3 knockdown led to increased tick mortality, with 77% of ticks dying post-infestation. The reduction of the secreted cement protein-mRNA levels resulted in 46% of ticks being incapable of correctly attaching to the host and significantly lower female weights post-feeding in comparison to the control group. The lachesin knockdown resulted in a 70% reduction of the levels associated with B. ovis infection in R. bursa SG and 70% mortality. These results improved our understanding of the role of tick SG genes in Babesia infection/proliferation and tick feeding. Moreover, lachesin, vitellogenin-3, and secreted cement proteins were validated as candidate protective antigens for the development of novel tick and tick-borne disease control measures.
- Vitellogenin and Lachesin knockdown in Rhipicephalus bursa influence in feeding and pathogen acquisitionPublication . Antunes, S.; Ferrolho, J.; Nobre, J.; Couto, J.; Santos, A.S.; Santos-Silva, M.M.; de la Fuente, J.; Domingos, A.Rhipicephalus bursa is considered as a multi-host tick being the primary hosts of this species, cattle, sheep and goats. R. bursa is widely distributed in the Mediterranean region and has been described as being involved in the transmission of agents of the genus Anaplasma, Babesia, Theileria, Rickettsia among others, with a known impact on animal health. Control of ticks by vaccination has the advantages of being costeffective, reducing environment contamination and preventing the selection of drugresistant ticks. The major constrain in the development of new anti-tick vaccines is still the identification of effective antigens. The present work studies the influence of tick feeding in gene expression as well as interactions between R. bursa tick and the protozoa B. ovis using silencing of genes by RNA interference (RNAi).