Pilgrim, Jack 
ORCID: 0000-0002-2941-1482, Siozios, Stefanos ORCID: 0000-0002-1104-7061, Baylis, Matthew ORCID: 0000-0003-0335-187X and Hurst, Gregory DD ORCID: 0000-0002-7163-7784
(2020)
The Tissue Tropisms and Transstadial Transmission of a Rickettsia Endosymbiont in the Highland Midge, Culicoides impunctatus (Diptera: Ceratopogonidae).
Applied and Environmental Microbiology, 86 (20).
e01492-e01420.
Abstract
Rickettsia are a group of intracellular bacteria which can manipulate host reproduction and alter sensitivity to natural enemy attack in a diverse range of arthropods. The maintenance of Rickettsia endosymbionts in insect populations can be achieved through both vertical and horizontal transmission routes. For example, the presence of the symbiont in the follicle cells and salivary glands of Bemisia whiteflies allows Belli group Rickettsia transmission via the germline and plants, respectively. However, the transmission routes of other Rickettsia, such as those in the Torix group of the genus, remain underexplored. Through fluorescence in-situ hybridisation (FISH) and transmission electron microscopy (TEM) screening, this study describes the pattern of Torix Rickettsia tissue tropisms in the highland midge, Culicoides impunctatus (Diptera: Ceratopogonidae). Of note is high intensity of infection of the ovarian suspensory ligament, suggestive of a novel germline targeting strategy. Additionally, localisation of the symbiont in tissues of several developmental stages suggests transstadial transmission is a major route of ensuring maintenance of Rickettsia within C. impunctatus populations. Aside from providing insights into transmission strategies, Rickettsia presence in the fat body of larvae indicates potential host fitness and vector capacity impacts to be investigated in the future.Importance Statement Microbial symbionts of disease vectors have garnered recent attention due to their ability to alter vectorial capacity. Their consideration as a means of arbovirus control depends on symbiont vertical transmission which leads to spread of the bacteria through a population. Previous work has identified a Rickettsia symbiont present in several species of biting midges (Culicoides spp.), which transmit bluetongue and Schmallenberg arboviruses. However, symbiont transmission strategies and host effects remain underexplored. In this study, we describe the presence of Rickettsia in the ovarian suspensory ligament of Culicoides impunctatus Infection of this organ suggests the connective tissue surrounding developing eggs is important for ensuring vertical transmission of the symbiont in midges and possibly other insects. Additionally, our results indicate Rickettsia localisation in the fat body of Culicoides impunctatus As the arboviruses spread by midges often replicate in the fat body, this location implies possible symbiont-virus interactions to be further investigated.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | symbiosis, microbial ecology, Rickettsia, Culicoides, arthropod vectors, tissue tropisms, vector biology |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 27 Aug 2020 13:42 |
| Last Modified: | 18 Jan 2023 23:36 |
| DOI: | 10.1128/aem.01492-20 |
| Open Access URL: | https://aem.asm.org/content/early/2020/08/11/AEM.0... |
| Related URLs: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3098928 |
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