Advanced search
Start date
Betweenand
Related content
(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Virulence genes of Rickettsia rickettsii are differentially modulated by either temperature upshift or blood-feeding in tick midgut and salivary glands

Full text
Author(s):
Galletti, Maria Fernanda B. M. ; Fujita, Andre ; Rosa, Rafael D. ; Martins, Larissa A. ; Soares, Herbert S. ; Labruna, Marcelo B. ; Daffre, Sirlei ; Fogaca, Andrea C.
Total Authors: 8
Document type: Journal article
Source: PARASITES & VECTORS; v. 9, JUN 10 2016.
Web of Science Citations: 7
Abstract

Background: Rickettsia rickettsii, the etiological agent of Rocky Mountain spotted fever, is transmitted to humans by ticks. During tick feeding, R. rickettsii is exposed to both temperature elevation and components of the blood meal, which have previously been associated with the reactivation of its virulence. These environmental stimuli were also reported to modulate virulence genes of R. rickettsii infecting a set of organs of adult females of its natural vector, Amblyomma aureolatum. Methods: In this study, we determined the effects of a temperature upshift, blood-feeding, and both stimuli simultaneously on the expression of 85 selected genes of R. rickettsii infecting either the midgut (MG) or salivary glands (SG) of male and female A. aureolatum by microfluidic high-throughput RT-qPCR. These two organs are key for acquisition of this bacterium by the tick and transmission to the vertebrate host, respectively. Results: Data showed that these environmental stimuli exert distinct effects on rickettsial transcription depending on the colonized organ and gender of the vector. Temperature upshift induced the majority of differentially expressed genes of R. rickettsii in tick SG, including tRNA synthetases encoding genes. On the contrary, blood-feeding downregulated most of differentially expressed genes in both organs, but induced type IV secretion system components and OmpB in tick MG. The combined effects of both stimuli resulted in a merged gene expression profile representing features of each stimulus analyzed independently, but was more similar to the profile induced by blood-feeding. Conclusion: The upregulation of the majority of differentially expressed genes in tick SG by temperature upshift suggests that this stimulus is important to prepare R. rickettsii for transmission to the vertebrate host. Blood-feeding, on the other hand, induced important virulence genes in the tick MG, which might be associated with colonization of the tick and transmission to the vertebrate host. The role of the proteins identified in this study must be addressed and might help to define future targets to block tick infection, thereby preventing RMSF. To our knowledge, this is the first transcriptional tissue-specific study of a virulent strain of R. rickettsii infecting a natural tick vector. (AU)

FAPESP's process: 13/26450-2 - Molecular characterization of the interactions among ticks, rickettsiae and vertebrate hosts
Grantee:Sirlei Daffre
Support Opportunities: Research Projects - Thematic Grants