Innate immunity is the first line of defense against pathogens and is highly conserved from insects to humans. While many key facets of the innate immune system have been elucidated, there is a fundamental gap in our knowledge of the pathways that restrict arthropod-borne viral infections both in the insect vector and the mammalian host. Importantly, a molecular understanding of these mechanisms is essential to overcome the lack of effective antiviral therapeutics and combat human disease. The Drosophila immune response is highly homologous to that of vector insects and additionally shares striking similarities with mammalian innate immunity. Thus, discoveries in fruit flies may have profound impacts on human health by identifying novel approaches to interfere with disease transmission in vector species and revealing conserved immune pathways in mammals. One essential pathway that restricts the human arbovirus Vesicular Stomatitis virus (VSV) in Drosophila is autophagy, an ancient intracellular degradative program evolutionarily conserved from yeast to humans. Based on preliminary data, this response depends on the interaction between VSV and a previously uncharacterized Toll receptor, Toll-7;however, the downstream pathways and global significance of Toll receptors remain unknown. The long-term objective of this application is to define the molecular mechanisms by which Drosophila recognizes viral infections to induce protective antiviral autophagy. Because these pathways share a number of molecular and functional similarities to mammalian TLR pathways, and increasing in vitro data suggest that TLRs activate autophagy during a variety of infections, the proposed research also has the potential to extend our understanding of the mechanisms that link innate immunity to autophagy in mammals. As such, this application proposes three specific aims: (1) elucidate the mechanism by which virus is targeted by autophagy;(2) identify the role of Toll receptors in antiviral autophagy and defense;and (3) explore the signaling pathways that link virus recognition to autophagy in flies and mammals. These studies will expand our understanding of the molecular mechanisms underlying antiviral autophagy in flies, as well as conserved autophagy-inducing pathways likely downstream of TLR signaling in mammals. Moreover, this research opens a previously unappreciated and unexplored realm of Toll receptors in immunity, which may serve as effective targets for novel vector-based antiviral therapeutics given their conservation in other insects.

Public Health Relevance

Due to the dearth of antiviral therapeutics, there is an urgent need for the discovery of novel mechanisms by which we can overcome viral pathogens. This project focuses on the understanding of specific cellular factors and signaling pathways that are important to initiate and execute an intrinsic antiviral program during infection. We will take advantage of powerful genetic tools available in fruit flies to identify conserved pathways responsible for antiviral responses to a virus that infects both mammalian and insect cells. Since we are studying viruses that are naturally transmitted by insects, these studies may have a direct impact on the control of vector mosquitoes that transmit such pathogens. Furthermore, due to the conservation of innate pathways with humans, we will test whether these same pathways are operative in human cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
2R01AI074951-06A1
Application #
8502871
Study Section
Innate Immunity and Inflammation Study Section (III)
Program Officer
Leitner, Wolfgang W
Project Start
2007-07-01
Project End
2017-12-31
Budget Start
2013-01-01
Budget End
2013-12-31
Support Year
6
Fiscal Year
2013
Total Cost
$156,667
Indirect Cost
$58,750
Name
University of Pennsylvania
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Bayer, Avraham; Lennemann, Nicholas J; Ouyang, Yingshi et al. (2016) Type III Interferons Produced by Human Placental Trophoblasts Confer Protection against Zika Virus Infection. Cell Host Microbe 19:705-12
Molleston, Jerome M; Sabin, Leah R; Moy, Ryan H et al. (2016) A conserved virus-induced cytoplasmic TRAMP-like complex recruits the exosome to target viral RNA for degradation. Genes Dev 30:1658-70
Zhang, Rong; Miner, Jonathan J; Gorman, Matthew J et al. (2016) A CRISPR screen defines a signal peptide processing pathway required by flaviviruses. Nature 535:164-8
Kramer, Marianne C; Liang, Dongming; Tatomer, Deirdre C et al. (2015) Combinatorial control of Drosophila circular RNA expression by intronic repeats, hnRNPs, and SR proteins. Genes Dev 29:2168-82
Ramage, Holly; Cherry, Sara (2015) Virus-Host Interactions: From Unbiased Genetic Screens to Function. Annu Rev Virol 2:497-524
Panda, Debasis; Gold, Beth; Tartell, Michael A et al. (2015) The transcription factor FoxK participates with Nup98 to regulate antiviral gene expression. MBio 6:
Hopkins, Kaycie C; Tartell, Michael A; Herrmann, Christin et al. (2015) Virus-induced translational arrest through 4EBP1/2-dependent decay of 5'-TOP mRNAs restricts viral infection. Proc Natl Acad Sci U S A 112:E2920-9
Panda, Debasis; Cherry, Sara (2015) A genome-wide RNAi screening method to discover novel genes involved in virus infection. Methods 91:75-81
Sansone, Christine L; Cohen, Jonathan; Yasunaga, Ari et al. (2015) Microbiota-Dependent Priming of Antiviral Intestinal Immunity in Drosophila. Cell Host Microbe 18:571-81
Beiting, Daniel P; Hidano, Shinya; Baggs, Julie E et al. (2015) The Orphan Nuclear Receptor TLX Is an Enhancer of STAT1-Mediated Transcription and Immunity to Toxoplasma gondii. PLoS Biol 13:e1002200

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