Arthropod-borne virus (arbovirus) diseases remain a significant burden on global public health. Maintenance of arboviruses in nature requires a biological transmission cycle that involves alternating virus replication in a susceptible vertebrate host and a blood feeding arthropod. While the vertebrate infection is acute and often associated with disease, continual transmission of virus depends on the establishment of a persistent, non-pathogenic infection in the arthropod. Both the virus and arthropod host clearly benefit from this non-pathogenic infection. Indeed, current models of vectorial capacity predict that transmission rates will be highest when arboviral infection has no effect on mosquito survival. The existence of endogenous mechanisms that quantitatively limit virus yields, termed """"""""modulation"""""""", has been advanced as an explanation for the apparent resistance of mosquito cells to the potential cytopathic effects of arboviruses. However, this has never been demonstrated experimentally. Nor have previous observations of modulation, made by arbovirologists over a period of more than 30 years, been directly linked to a specific immune mechanism. Our studies have established a link between arbovirus modulation, and recent evidence indicating that RNA interference (RNAi) functions as an innate anti-viral immune response in arthropods. Accomplishing the specific aims outlined here is designed to provide a comprehensive assessment of intrinsic and extrinsic factors influencing the relationship between RNAi-based modulation and the establishment of productive arbovirus infections in the mosquito. The specific goals of the proposed research are to 1) characterize the mechanism by which alphaviruses limit immune modulation in natural vector hosts, 2) determine the precise effects of temperature on RNAi and RNAi-based modulation of alphaviruses, and 3) determine the role of an RNAi-based immune response in modulating flavivirus infections in natural vector hosts. We believe that understanding how arboviruses interact with RNAi- based modulation will address glaring gaps in our knowledge of mosquito vector competence, and may ultimately form the basis of RNAi-based transgenic and field diagnostic approaches for disease control.

Public Health Relevance

Arthropod-borne virus (arbovirus) diseases such as yellow fever remain a significant burden on global public health. This proposal deals directly with select agent and biosafety level 3 viruses which cause encephalitis or hemorrhagic fever.
We aim to describe mechanisms used by these pathogens to successfully infect mosquito vectors. This knowledge is vital to understanding and predicting how arboviral epidemics are initiated, spread, and maintained, and may ultimately form the basis of RNAi- based transgenic and field diagnostic approaches for disease control.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Vector Biology Study Section (VB)
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Costero, Adriana
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Virginia Polytechnic Institute and State University
Schools of Earth Sciences/Natur
United States
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Samuel, Glady Hazitha; Adelman, Zach N; Myles, Kevin M (2018) Antiviral Immunity and Virus-Mediated Antagonism in Disease Vector Mosquitoes. Trends Microbiol 26:447-461
Samuel, Glady Hazitha; Adelman, Zach N; Myles, Kevin M (2016) Temperature-dependent effects on the replication and transmission of arthropod-borne viruses in their insect hosts. Curr Opin Insect Sci 16:108-113
Samuel, Glady Hazitha; Wiley, Michael R; Badawi, Atif et al. (2016) Yellow fever virus capsid protein is a potent suppressor of RNA silencing that binds double-stranded RNA. Proc Natl Acad Sci U S A 113:13863-13868
Basu, Sanjay; Aryan, Azadeh; Overcash, Justin M et al. (2015) Silencing of end-joining repair for efficient site-specific gene insertion after TALEN/CRISPR mutagenesis in Aedes aegypti. Proc Natl Acad Sci U S A 112:4038-43
Allen, William J; Wiley, Michael R; Myles, Kevin M et al. (2014) Steered molecular dynamics identifies critical residues of the Nodamura virus B2 suppressor of RNAi. J Mol Model 20:2092
O'Neal, Scott T; Samuel, Glady Hazitha; Adelman, Zach N et al. (2014) Mosquito-borne viruses and suppressors of invertebrate antiviral RNA silencing. Viruses 6:4314-31
Adelman, Zach N; Anderson, Michelle A E; Wiley, Michael R et al. (2013) Cooler temperatures destabilize RNA interference and increase susceptibility of disease vector mosquitoes to viral infection. PLoS Negl Trop Dis 7:e2239
Lucas, Keira J; Myles, Kevin M; Raikhel, Alexander S (2013) Small RNAs: a new frontier in mosquito biology. Trends Parasitol 29:295-303
Morazzani, Elaine M; Wiley, Michael R; Murreddu, Marta G et al. (2012) Production of virus-derived ping-pong-dependent piRNA-like small RNAs in the mosquito soma. PLoS Pathog 8:e1002470
Adelman, Z N; Anderson, M A E; Liu, M et al. (2012) Sindbis virus induces the production of a novel class of endogenous siRNAs in Aedes aegypti mosquitoes. Insect Mol Biol 21:357-68

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