Browsing by Author "Nobre, J."
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- 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).