Martins Larissa A, Galletti Maria F B de Melo, Ribeiro José M, Fujita André, Costa Francisco B, Labruna Marcelo B, Daffre Sirlei, Fogaça Andréa C
Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São PauloSão Paulo, Brazil.
Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious DiseasesRockville, MD, USA.
Front Cell Infect Microbiol. 2017 Apr 28;7:129. doi: 10.3389/fcimb.2017.00129. eCollection 2017.
is a tick-borne obligate intracellular bacterium that causes Rocky Mountain Spotted Fever (RMSF). In Brazil, two species of ticks in the genus and , are incriminated as vectors of this bacterium. Importantly, these two species present remarkable differences in susceptibility to infection, where is more susceptible than . In the current study, and ticks were fed on suitable hosts previously inoculated with , mimicking a natural infection. As control, ticks were fed on non-infected animals. Both midgut and salivary glands of all positively infected ticks were colonized by . We did not observe ticks with infection restricted to midgut, suggesting that important factors for controlling rickettsial colonization were produced in this organ. In order to identify such factors, the total RNA extracted from the midgut (MG) was submitted to next generation RNA sequencing (RNA-seq). The majority of the coding sequences (CDSs) of differentially expressed by infection were upregulated, whereas most of modulated CDSs of were downregulated. The functional categories that comprise upregulated CDSs of , for instance, metabolism, signal transduction, protein modification, extracellular matrix, and immunity also include CDSs of that were downregulated by infection. This is the first study that reports the effects of an experimental infection with the highly virulent on the gene expression of two natural tick vectors. The distinct transcriptional profiles of MG of and upon infection stimulus strongly suggest that molecular factors in this organ are responsible for delineating the susceptibility to . Functional studies to determine the role played by proteins encoded by differentially expressed CDSs in the acquisition of are warranted and may be considered as targets for the development of strategies to control the tick-borne pathogens as well as to control the tick vectors.
是一种通过蜱传播的专性细胞内细菌，可引起落基山斑疹热（RMSF）。在巴西，属和属的两种蜱被认为是这种细菌的传播媒介。重要的是，这两种蜱在对感染的易感性上存在显著差异，其中比更易感染。在本研究中，和蜱以预先接种了的合适宿主为食，模拟自然感染。作为对照，蜱以未感染的动物为食。所有呈阳性感染的蜱的中肠和唾液腺都被定殖。我们没有观察到感染仅限于中肠的蜱，这表明控制立克次体定殖的重要因子是在这个器官中产生的。为了确定这些因子，从中肠（MG）提取的总RNA被提交进行下一代RNA测序（RNA-seq）。因感染而差异表达的大多数编码序列（CDS）上调，而大多数被调节的的CDS下调。例如，包含上调的的CDS的功能类别，如代谢、信号转导、蛋白质修饰、细胞外基质和免疫，也包括因感染而下调的的CDS。这是第一项报道用高毒力的进行实验感染对两种天然蜱传播媒介基因表达影响的研究。和的MG在感染刺激下不同的转录谱强烈表明，这个器官中的分子因子决定了对的易感性。确定差异表达的CDS编码的蛋白质在获取中的作用的功能研究是有必要的，并且可以被视为开发控制蜱传播病原体以及控制蜱传播媒介策略的靶点。
