Project description:During blood feeding haematophagous arthropods inject into their hosts a cocktail of salivary proteins whose main role is to counteract host haemostasis, inflammation and immunity. However, animal body fluids are known to also carry miRNAs. To get insights into saliva and salivary gland miRNA repertoires of the African malaria vector Anopheles coluzzii we used small RNA-Seq and identified 214 miRNAs, including tissue-enriched, sex-biased and putative novel anopheline miRNAs. Noteworthy, miRNAs were asymmetrically distributed between saliva and salivary glands, suggesting that selected miRNAs may be preferentially directed toward mosquito saliva. The evolutionary conservation of a subset of saliva miRNAs in Anopheles and Aedes mosquitoes, and in the tick Ixodes ricinus, supports the idea of a non-random occurrence pointing to their possible physiological role in blood feeding by arthropods. Strikingly, eleven of the most abundant An. coluzzi saliva miRNAs mimicked human miRNAs. Prediction analysis and search for experimentally validated targets indicated that miRNAs from An. coluzzii saliva may act on host mRNAs involved in immune and inflammatory responses. Overall, this study raises the intriguing hypothesis that miRNAs injected into vertebrates with vector saliva may contribute to host manipulation with possible implication for vector-host interaction and pathogen transmission.
Project description:Plasmodium sporozoites are injected, in addition to saliva, into animal hosts when a female Anopheles mosquito takes a blood meal. The molecular components of saliva that interact with Plasmodium during this process are poorly characterized. Here we collected Plasmodium sporozoites directly from salivating Anopheles mosquitoes and looked for the presence of vector proteins that could be interacting with the parasites during transmission for further characterization.
Project description:During probing and feeding, an infected mosquito injects both virus and saliva into the host skin. The presence of mosquito saliva in the skin increases arbovirus pathogenesis in the bitten host, however the exact mechanism behind this remains to be determined. It is hypothesized that disease enhancement is dependent on the function of the dermal endothelium, where an increased permeability aids in the influx of virus-susceptible cells to the bite site and therefore more cells for the virus to replicate in. Here, we investigate and compare the effects of saliva from Culex and Aedes species on the human dermal endothelial cell function in vitro. Furthermore, we investigate the effect of Culex saliva on West Nile virus (WNV) pathogenesis in a mouse model. We found that salivary gland extract from anthropophilic mosquito species (Aedes and Cx. pipiens molestus) induce permeability of the human dermal endothelium, while an ornithophilic mosquito species (Cx. pip. pipiens) does not. We identified that this effect is due to the presence of protease(s) in Cx. pipiens molestus saliva. In addition, we show that the presence of Cx. saliva at the WNV inoculation site in vivo leads to more consistent weight loss, increased permeability in the inoculation site, and increased mortality compared to inoculation of WNV alone. Moving forward, identification and characterization of novel salivary proteins from similar but genetically distinct mosquito species will advance the development of intervention methods to combat potential transmission risks and disease severity of emerging mosquito-borne pathogens.
Project description:Dengue viruses are mosquito-borne human pathogens whose global incidence in human infections is rising. Surveillance is hampered by the requirement for blood-based diagnostics. Interestingly, in several prior research studies dengue virus nucleic acids and proteins could be detected in saliva, making saliva-based diagnostics a plausible alterative. However, the temporal relationships between exposure, viremia, salivary accumulation, and symptom onset remain poorly defined. To address this knowledge gap, nine participants were enrolled in clinical trial NCT04298138 to receive an inoculation with an attenuated dengue virus (DENV-3 strain CH53489). Matched blood and saliva specimens were collected over 10 days. Dengue virus genomes could be detected by RT-qPCR in both blood and saliva before the onset of symptoms in most individuals. The earliest time of detection in blood and saliva was 3.4 and 5.0 days post infection, respectively. Using this sample set, we also measured host transcriptional responses to dengue infection in both biospecimens from two participants using RNA sequencing. Strikingly, far more human genes showed increased transcript abundance exclusively in PBMCs (4%) or saliva (15%) than in both compartments simultaneously (5%), revealing compartment-specific host responses. For 21 of the human transcripts that increased in response to dengue infection, we quantified their daily abundance across the course of DENV-3 infection in all study participants. Together, these findings demonstrate that sensitive dengue virus detection in saliva should be possible and establish that both blood and saliva capture early host responses to infection.
Project description:Mosquito saliva facilitates blood feeding through the anti-haemostatic, anti-inflammatory and immunomodulatory properties of its proteins. However, the potential contribution of non-coding RNAs to host manipulation is still poorly understood. We analysed small RNAs from Aedes aegypti saliva and salivary glands and show here that chikungunya virus-infection triggers both the siRNA and piRNA antiviral pathways with limited effects on miRNA expression profiles. Saliva appears enriched in specific miRNA subsets and its miRNA content is well conserved among mosquitoes and ticks, clearly pointing to a non-random sorting and occurrence. Finally, we provide evidence that miRNAs from Ae. aegypti saliva may target human immune and inflammatory pathways, as indicated by prediction analysis and searching for experimentally validated targets of identical human miRNAs. Overall, we believe these observations convincingly support a scenario where both proteins and miRNAs from mosquito saliva are injected into vertebrates during blood feeding and contribute to the complex vector-host-pathogen interactions.
Project description:Mosquito saliva contains bioactive factors that enhance viral infection, with sialokinin identified as a key contributor to vascular leakage and viral spread in mice. Understanding effect of sialokinin on human moncoytes, the most important innate cells that responsible for the viral-induced inflammatory, will provide important insight to host-virus-vector interaction in arbovirus infection.
Project description:Anopheline mosquitoes transmit Plasmodium parasites to humans, and are responsible for an estimated 219 million cases of malaria, leading to over 400,000 deaths annually. The mosquito’s immune system limits Plasmodium infection in several ways, and hemocytes, the insect white blood cells, are key players in these defense responses. However, the full functional diversity of mosquito hemocytes and their developmental trajectories have not been established. We use bulk RNA sequencing (scRNA-seq) to analyze the transcriptional profiles of hemocytes, of guts, and of carcasses of mosquito hemocytes in response to blood feeding or infection with Plasmodium. Data from three independent biological replicates for each condition and time-point (day 0, 1, 2, 3, and 7 after sugar-feeding, blood-feeding or P. berghei infection).