Members of the family Flaviviridae are important human pathogens and fall within the NIAID class A, B and C priorities, depending on the virus species. Like many other viruses, flaviviruses have evolved complex mechanisms to interact with the host immune response. The earliest immune responses to infection involve components of the innate immune system, starting with the recognition of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs), such as toll-like receptors (TLRs), and intracellular RNA helicases, such as RIG-I and Mda-5. PAMP recognition results in activation of specific signal transduction pathways that result in production of proinflammatory cytokines, such as type I interferon (IFN), TNFa and others. Type I interferon is one of the most important mediators of the early immune response. Mice deficient in IFN signaling are more susceptible to flaviviruses and pretreatment of mice with type I IFN can prevent flavivirus disease. One of the major pathways of IFN synthesis in viral infection is the stimulation of plasmacytoid dendritic cells (pDCs) via TLRs 7, 8 or 9. While several studies have indicated that flaviviruses are able to stimulate pDCs to produce IFNa, the mechanisms of this stimulation are not understood. Our preliminary data indicates that mosquito-derived flaviviruses are unable to stimulate TLR7 while viruses grown in mammalian cells strongly stimulate TLR7. We hypothesize that differential glycosylation of viruses grown in either mammalian or insect cells accounts for theses differences. In addition, our previous work has shown that WNV, and more specifically its NS1 protein, is able to interfere with TLRS and TLR7 signal transduction which could prevent further activation of these pathways after initial nfection has been established. TLR7 is a PRR that recognizes ssRNA and activates the transcription factors NFkB and interferon-regulatory factor 7 (IRF7), resulting in transcription of IFNa and other cytokines. NS1 is glycoprotein secreted to high levels during flavivirus infection that can be endocytosed by several cell types. We hypothesize that secreted NS1 is able to inhibit TLR7 function and thus contributes to viral pathogenesis. We have developed three specific Aims to address our hypotheses.
In Aim 1 we will identify mechanisms of flavivirus recognition by TLR7 with a specific focus on differential glycosylation of viruses grown in either mammalian or insect cells.
In Aim 2 we will determine mechanisms of TLR7 inhibition by the lavivirus NS1 proteins, focussing on a potential role for secreted NS in this inhibition.
In Aim 3 we will nvestigate the contribution of TLR7 signaling to WNV pathogenesis.
IMPACT: We have identified a novel role for a flavivirus nonstructural protein, the inhibition of TLR signaling. This proposal aims to delineate the mechanism(s) of this interference and the roles that TLRs play in the response to flavivirus infection. We expect to gain important information about viral immune evasion mechanisms and a novel role for a replication-associated protein in this process.
|Ashbrook, Alison W; Lentscher, Anthony J; Zamora, Paula F et al. (2016) Antagonism of the Sodium-Potassium ATPase Impairs Chikungunya Virus Infection. MBio 7:|
|Bowles, R D; Karikari, I O; VanDerwerken, D N et al. (2016) In vivo luminescent imaging of NF-ÎºB activity and NF-ÎºB-related serum cytokine levels predict pain sensitivities in a rodent model of peripheral neuropathy. Eur J Pain 20:365-76|
|Alayli, Farah; Scholle, Frank (2016) Dengue virus NS1 enhances viral replication and pro-inflammatory cytokine production in human dendritic cells. Virology 496:227-36|
|Bates, John T; Pickens, Jennifer A; Schuster, Jennifer E et al. (2016) Immunogenicity and efficacy of alphavirus-derived replicon vaccines for respiratory syncytial virus and human metapneumovirus in nonhuman primates. Vaccine 34:950-6|
|Fibriansah, Guntur; Tan, Joanne L; Smith, Scott A et al. (2015) A highly potent human antibody neutralizes dengue virus serotype 3 by binding across three surface proteins. Nat Commun 6:6341|
|de St Maurice, Annabelle; Grijalva, Carlos G; Fonnesbeck, Christopher et al. (2015) Racial and Regional Differences in Rates of Invasive Pneumococcal Disease. Pediatrics 136:e1186-94|
|Roberts, Lydia M; Ledvina, Hannah E; Tuladhar, Shraddha et al. (2015) Depletion of alveolar macrophages in CD11c diphtheria toxin receptor mice produces an inflammatory response. Immun Inflamm Dis 3:71-81|
|Smith, Scott A; Silva, Laurie A; Fox, Julie M et al. (2015) Isolation and Characterization of Broad and Ultrapotent Human Monoclonal Antibodies with Therapeutic Activity against Chikungunya Virus. Cell Host Microbe 18:86-95|
|Pulendran, Bali (2015) The varieties of immunological experience: of pathogens, stress, and dendritic cells. Annu Rev Immunol 33:563-606|
|Price, Aryn A; Sampson, Timothy R; Ratner, Hannah K et al. (2015) Cas9-mediated targeting of viral RNA in eukaryotic cells. Proc Natl Acad Sci U S A 112:6164-9|
Showing the most recent 10 out of 375 publications