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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

The Transcriptome of the Salivary Glands of Amblyomma aureolatum Reveals the Antimicrobial Peptide Microplusin as an Important Factor for the Tick Protection Against Rickettsia rickettsii Infection

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Author(s):
Martins, Larissa A. [1] ; Malossi, Camila D. [1, 2] ; Galletti, Maria F. B. de M. [1, 2] ; Ribeiro, Jose M. [3] ; Fujita, Andre [4] ; Esteves, Eliane [5] ; Costa, Francisco B. [6] ; Labruna, Marcelo B. [6] ; Daffre, Sirlei [1] ; Fogaca, Andrea C. [1]
Total Authors: 10
Affiliation:
[1] Univ Sao Paulo, Dept Parasitol, Inst Ciencias Biomed, Sao Paulo - Brazil
[2] Univ Estadual Paulista, Inst Biotecnol, Botucatu, SP - Brazil
[3] NIAID, Lab Malaria & Vector Res, 9000 Rockville Pike, Bethesda, MD 20892 - USA
[4] Univ Sao Paulo, Inst Matemat & Estat, Dept Ciencia Comp, Sao Paulo - Brazil
[5] Univ Sao Paulo, Inst Ciencias Biomed, Dept Imunol, Sao Paulo - Brazil
[6] Univ Sao Paulo, Dept Med Vet Prevent & Saude Anim, Fac Med Vet & Zootecnia, Sao Paulo - Brazil
Total Affiliations: 6
Document type: Journal article
Source: FRONTIERS IN PHYSIOLOGY; v. 10, MAY 3 2019.
Web of Science Citations: 1
Abstract

The salivary glands (SG) of ixodid ticks play a pivotal role in blood feeding, producing both the cement and the saliva. The cement is an adhesive substance that helps the attachment of the tick to the host skin, while the saliva contains a rich mixture of antihemostatic, anti-inflammatory, and immunomodulatory substances that allow ticks to properly acquire the blood meal. The tick saliva is also a vehicle used by several pathogens to be transmitted to the vertebrate host, including various bacterial species from the genus Rickettsia. Rickettsia rickettsii is a tick-borne obligate intracellular bacterium that causes the severe Rocky Mountain spotted fever. In Brazil, the dog yellow tick Amblyomma aureolatum is a vector of R. rickettsii. In the current study, the effects of an experimental infection with R. rickettsii on the global gene expression profile of A. aureolatum SG was determined by next-generation RNA sequencing. A total of 260 coding sequences (CDSs) were modulated by infection, among which 161 were upregulated and 99 were downregulated. Regarding CDSs in the immunity category, we highlight one sequence encoding one microplusin-like antimicrobial peptide (AMP) (Ambaur-69859). AMPs are important effectors of the arthropod immune system, which lack the adaptive response of the immune system of vertebrates. The expression of microplusin was confirmed to be significantly upregulated in the SG as well as in the midgut (MG) of infected A. aureolatum by a quantitative polymerase chain reaction preceded by reverse transcription. The knockdown of the microplusin expression by RNA interference caused a significant increase in the prevalence of infected ticks in relation to the control. In addition, a higher rickettsial load of one order of magnitude was recorded in both the MG and SG of ticks that received microplusin-specific dsRNA. No effect of microplusin knockdown was observed on the R. rickettsii transmission to rabbits. Moreover, no significant differences in tick engorgement and oviposition were recorded in ticks that received dsMicroplusin, demonstrating that microplusin knockdown has no effect on tick fitness. Further studies must be performed to determine the mechanism of action of this AMP against R. rickettsii. (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