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Published on: August 14, 2017
A salivary protein of Aedes aegypti promotes dengue-2 virus replication and transmission
Chalida Sri-In1, Shih-Che Weng2, Wen-Yu Chen3
1Department of Entomology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, Taiwan.
Abstract:
Although dengue is the most prevalent arthropod-borne viral disease in humans, no effective medication or vaccine is presently available. Previous studies suggested that mosquito salivary proteins influence infection by the dengue virus (DENV) in the mammalian host. However, the effects of salivary proteins on DENV replication within the Aedes aegypti mosquito remain largely unknown. In this study, we investigated the effect of a specific salivary protein (named AaSG34) on DENV serotype 2 (DENV2) replication and transmission. We showed that transcripts of AaSG34 were upregulated in the salivary glands of Aedes aegypti mosquitoes after a meal of blood infected with DENV2. Transcripts of the dengue viral genome and envelop protein in the salivary glands were significantly diminished after an infectious blood meal when AaSG34 was silenced. The effect of AaSG34 on DENV2 transmission was investigated in Stat1-deficient mice. The intradermal inoculation of infectious mosquito saliva induced hemorrhaging in the Stat1-deficient mice; however, saliva from the AaSG34-silenced mosquitoes did not induce hemorrhaging, suggesting that AaSG34 enhances DENV2 transmission. This is the first report to demonstrate that the protein AaSG34 promotes DENV2 replication in mosquito salivary glands and enhances the transmission of the virus to the mammalian host.
Insights
Aedes aegypti mosquito salivary protein AaSG34 promotes dengue virus type 2 replication in the mosquito. This protein also enhances dengue virus transmission to mammals, highlighting a new target for disease control.
Area of Science:
- Medical Entomology
- Virology
- Infectious Diseases
Background:
- Dengue virus (DENV) is a major global health threat, with no available vaccines or treatments.
- Mosquito salivary proteins are known to influence DENV infection in mammals, but their role in mosquito DENV replication is unclear.
- Aedes aegypti is the primary vector for DENV transmission.
Purpose of the Study:
- To investigate the role of the Aedes aegypti salivary protein AaSG34 in DENV serotype 2 (DENV2) replication within the mosquito.
- To determine the effect of AaSG34 on DENV2 transmission to a mammalian host.
Main Methods:
- Quantified AaSG34 and DENV2 RNA levels in Aedes aegypti salivary glands after infectious blood meals.
- Utilized RNA interference (RNAi) to silence AaSG34 expression in mosquitoes.
- Assessed DENV2 transmission and associated pathology (hemorrhaging) in Stat1-deficient mice inoculated with infectious saliva.
Main Results:
- AaSG34 transcripts were upregulated in mosquito salivary glands following a DENV2-infected blood meal.
- Silencing AaSG34 significantly reduced DENV2 genome and envelope protein RNA in salivary glands.
- Saliva from AaSG34-silenced mosquitoes failed to induce hemorrhaging in mice, unlike saliva from control mosquitoes, indicating reduced transmission.
Conclusions:
- The salivary protein AaSG34 plays a crucial role in promoting DENV2 replication within the Aedes aegypti mosquito.
- AaSG34 enhances the transmission efficiency of DENV2 from mosquitoes to mammalian hosts.
- AaSG34 represents a potential target for novel strategies to control dengue transmission.
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