Browsing by Author "Couto, 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.
- Molecular heterogeneity of Rhipicephalus sanguineus sensu lato and screening for Ehrlichia canis in mainland PortugalPublication . Santos, G.S.; Couto, J.; Silva-Perdosa, R.; Ferrolho, J.; Santos, A.S.; Santos-Silva, M.M.; Antunes, S.; Domingos, A.The present study aimed to expand knowledge regarding the molecular characterization of R. sanguineus s.l. in Portugal and to screen for ticks naturally infected with E. canis. A total of 113 R. sanguineus s.l. were collected questing or attached to domestic and wild animals from the 18 administrative regions of mainland Portugal. All the ticks were analyzed for the 16S rRNA and the partial sequences obtained showed high genetic similarities with specimens belonging to the temperate lineage. These sequences revealed eight haplotypes (H1‒H8), with a genetic distance ranging from 0.3% to 1.4%. A convenience sample representing approximately 75% of all the R. sanguineus s.l. ticks collected was tested for the presence of E. canis by qPCR for the dsb gene. No ticks were found to be infected with this pathogen. Accordingly, further studies are required to determine the role of the R. sanguineus s.l. temperate lineage in E. canis maintenance and transmission, as well as to elucidate if a different R. sanguineus s.l. lineage or other tick species act as E. canis vectors for dogs in Portugal.
- 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).