RNA viruses include important human pathogens such as hepatitis C, West Nile and dengue viruses and exhibit distinct genetic and immunological properties from DNA viruses. In plants and invertebrates, replication of RNA viruses triggers Dicer-dependent biogenesis of virus-derived small interfering RNAs (siRNAs) to guide specific antiviral immunity by RNA interference (RNAi). However, direct evidence supporting a similar antiviral role for the siRNA pathway in mammals is not available. We have obtained key mechanistic insights to the RNA-based antiviral immunity using Flock house virus infection of the fruit fly Drosophila melanogaster, which has been a powerful model for studies on both RNAi and innate immunity. We have recently reported production of a novel class of virus-derived small RNAs in cultured Drosophila cells known as PIWI- interacting RNAs (piRNAs), which are produced independently of Dicer in flies and mammals to silence transposable elements in the germline. Further genetic studies indicate a novel antiviral function for the piRNA pathway in the fruit fly that inhibits virus vertical transmission to the progeny. Ai 1 will determine the genetic requirements of the piRNA-directed antiviral defense and investigate the population, biogenesis and activity of viral piRNAs.
Aim 2 chose an arthropod-borne mammalian RNA virus that encodes a viral suppressor of RNAi (VSR) to examine the hypothesis that antiviral RNAi is induced in the mammalian cells during the early stages of viral RNA replication. We found that infection of a VSR-deficient mutant of the virus was effectively suppressed in mammalian cells and was associated with production of viral siRNAs that share key properties with the viral siRNAs produced in the fruit fly in response to Flock house virus infection.
Aim 2 will investigate the biogenesis of viral siRNAs in mammalian cells and determine if the detected viral siRNAs direct specific antiviral defense in the mammalian host cells. These studies will likely open up a new area of research on the function of viral piRNAs and establish a mammalian system to investigate the biogenesis and antiviral function of virus-derived small RNAs.

Public Health Relevance

The fruit fly has been a powerful model for elucidating the molecular mechanisms of both innate immunity and RNA interference in humans. Many positive-strand RNA viruses such as hepatitis C virus, poliovirus, dengue virus and West Nile virus are important human pathogens. Thus, it is likely that the proposed studies on the immune responses induced by model positive-strand RNA viruses in the fruit fly and mammalian model systems will facilitate understanding the human immune responses to important RNA viruses.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
2R01AI052447-10
Application #
8302758
Study Section
Virology - B Study Section (VIRB)
Program Officer
Cassetti, Cristina
Project Start
2002-04-01
Project End
2017-04-30
Budget Start
2012-05-01
Budget End
2013-04-30
Support Year
10
Fiscal Year
2012
Total Cost
$369,889
Indirect Cost
$126,541
Name
University of California Riverside
Department
Other Basic Sciences
Type
Schools of Earth Sciences/Natur
DUNS #
627797426
City
Riverside
State
CA
Country
United States
Zip Code
92521
Maillard, P V; Ciaudo, C; Marchais, A et al. (2013) Antiviral RNA interference in mammalian cells. Science 342:235-8
Li, Yang; Lu, Jinfeng; Han, Yanhong et al. (2013) RNA interference functions as an antiviral immunity mechanism in mammals. Science 342:231-4
Ding, Shou-Wei; Lu, Rui (2011) Virus-derived siRNAs and piRNAs in immunity and pathogenesis. Curr Opin Virol 1:533-44
Han, Yan-Hong; Luo, Ying-Jun; Wu, Qingfa et al. (2011) RNA-based immunity terminates viral infection in adult Drosophila in the absence of viral suppression of RNA interference: characterization of viral small interfering RNA populations in wild-type and mutant flies. J Virol 85:13153-63
Wu, Qingfa; Luo, Yingjun; Lu, Rui et al. (2010) Virus discovery by deep sequencing and assembly of virus-derived small silencing RNAs. Proc Natl Acad Sci U S A 107:1606-11
Parameswaran, Poornima; Sklan, Ella; Wilkins, Courtney et al. (2010) Six RNA viruses and forty-one hosts: viral small RNAs and modulation of small RNA repertoires in vertebrate and invertebrate systems. PLoS Pathog 6:e1000764
Wu, Qingfa; Wang, Xianbing; Ding, Shou-Wei (2010) Viral suppressors of RNA-based viral immunity: host targets. Cell Host Microbe 8:12-5
Wang, Xian-Bing; Wu, Qingfa; Ito, Takao et al. (2010) RNAi-mediated viral immunity requires amplification of virus-derived siRNAs in Arabidopsis thaliana. Proc Natl Acad Sci U S A 107:484-9
Lu, Rui; Yigit, Erbay; Li, Wan-Xiang et al. (2009) An RIG-I-Like RNA helicase mediates antiviral RNAi downstream of viral siRNA biogenesis in Caenorhabditis elegans. PLoS Pathog 5:e1000286
Aliyari, Roghiyh; Ding, Shou-Wei (2009) RNA-based viral immunity initiated by the Dicer family of host immune receptors. Immunol Rev 227:176-88

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