The receptor tyrosine kinases (RTKs) of the TAM family - Tyro3, Axl, and Mer - are exploited by flaviviruses, such as West Nile Virus and Dengue Virus, to infect their target cells. The experiments of this proposal are designed to elucidate how TAM potentiation of infection is achieved. TAM RTKs are expressed on the surface of many cells, including dendritic cells and macrophages of the immune system, and neurons of the central nervous system. The ligands that bind to and activate the TAMs - Gas6 and Protein S (ProS) - have the ability to attach both to the phospholipid phosphatidylserine, expressed on the surface of flavivirus particles, and also to their cognate TAM receptor. In this way, the TAM ligands serve as a 'bridge'that links flaviviruses to the surface of cells that they will infect. t the same time, TAM receptor activation by Gas6 or ProS results in the inhibition of type I interferon (IFN) signaling, to which flaviviruses and many other viruses are sensitive.
In Aim 1, genetic, biochemical, and cell biological methods will be used to dissect the mechanisms through which TAM receptors facilitate flavivirus entry into human cells in vitro.
In Aim 2, these same methods will be used in experiments in dendritic cells and macrophages prepared from mice that carry targeted mutations in the Axl and Mer genes, and in CNS neurons prepared Tyro3 mutant mice, to define the TAM receptors and ligands that promote infection in different cellular settings, and to determine the extent to which TAM facilitation of flavivirus infection is dependent on the inhibition of type I IFN signaling.
In Aim 3, mice that carry mutations in the Tyro3, Axl, Mer, Gas6, and ProS genes will be used to assess the cellular and immunological consequences of specific deficits in TAM signaling for infection by West Nile Virus in vivo. Together, these experiments will delineate the molecular, cellular, and physiological features of a heretofore unknown pathway of flavivirus infection.

Public Health Relevance

Each year, ~100 million people are infected by West Nile Virus, Dengue Virus, and related flaviviruses, which are the most important arthropod-borne viruses causing disease in humans. As there is no specific therapy available for the majority of these infections, it is essential to public health to understand fully the genetic, cell biological and biochemical mechanisms that underlie the potentiation of flavivirus infection by receptor tyrosine kinases of the TAM family.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI101400-03
Application #
8703003
Study Section
Virology - B Study Section (VIRB)
Program Officer
Repik, Patricia M
Project Start
2012-08-21
Project End
2016-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
3
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Salk Institute for Biological Studies
Department
Type
DUNS #
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Agner, Shannon C; Klein, Robyn S (2018) Viruses have multiple paths to central nervous system pathology. Curr Opin Neurol 31:313-317
Thackray, Larissa B; Handley, Scott A; Gorman, Matthew J et al. (2018) Oral Antibiotic Treatment of Mice Exacerbates the Disease Severity of Multiple Flavivirus Infections. Cell Rep 22:3440-3453.e6
Garber, Charise; Vasek, Michael J; Vollmer, Lauren L et al. (2018) Astrocytes decrease adult neurogenesis during virus-induced memory dysfunction via IL-1. Nat Immunol 19:151-161
Lemke, Greg (2017) Phosphatidylserine Is the Signal for TAM Receptors and Their Ligands. Trends Biochem Sci 42:738-748
Richard, Audrey Stéphanie; Shim, Byoung-Shik; Kwon, Young-Chan et al. (2017) AXL-dependent infection of human fetal endothelial cells distinguishes Zika virus from other pathogenic flaviviruses. Proc Natl Acad Sci U S A 114:2024-2029
Klein, Robyn S (2017) Dual Blades: The Role of Musashi 1 in Zika Replication and Microcephaly. Cell Host Microbe 22:9-11
Klein, Robyn S; Hunter, Christopher A (2017) Protective and Pathological Immunity during Central Nervous System Infections. Immunity 46:891-909
Hastings, Andrew K; Yockey, Laura J; Jagger, Brett W et al. (2017) TAM Receptors Are Not Required for Zika Virus Infection in Mice. Cell Rep 19:558-568
Cain, Matthew D; Salimi, Hamid; Gong, Yongfeng et al. (2017) Virus entry and replication in the brain precedes blood-brain barrier disruption during intranasal alphavirus infection. J Neuroimmunol 308:118-130
Meertens, Laurent; Labeau, Athena; Dejarnac, Ophelie et al. (2017) Axl Mediates ZIKA Virus Entry in Human Glial Cells and Modulates Innate Immune Responses. Cell Rep 18:324-333

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