In RNA interference (RNAi), long double-stranded RNA is cleaved by the Dicer endonuclease into small interfering RNAs (siRNAs), which guide degradation of complementary RNAs. While RNAi mediates antiviral innate immunity in plants and many invertebrates, vertebrates have adopted a sequence-independent response and their Dicer produces siRNAs inefficiently because it is adapted to process small hairpin microRNA precursors in the gene-regulating microRNA pathway. Mammalian endogenous RNAi is thus a rudimentary pathway of unclear significance. To investigate its antiviral potential, we modified the mouse Dicer locus to express a truncated variant (DicerΔHEL1) known to stimulate RNAi and we analyzed how DicerΔHEL1/wt mice respond to four RNA viruses: coxsackievirus B3 and encephalomyocarditis virus from Picornaviridae; tick-borne encephalitis virus from Flaviviridae; and lymphocytic choriomeningitis virus (LCMV) from Arenaviridae. Increased Dicer activity in DicerΔHEL1/wt mice did not elicit any antiviral effect, supporting an insignificant antiviral function of endogenous mammalian RNAi in vivo. However, we also observed that sufficiently high expression of DicerΔHEL1 suppressed LCMV in embryonic stem cells and in a transgenic mouse model. Altogether, mice with increased Dicer activity offer a new benchmark for identifying and studying viruses susceptible to mammalian RNAi in vivo.
- MeSH
- DEAD-box RNA-helikasy genetika metabolismus MeSH
- malá interferující RNA genetika MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- přirozená imunita * genetika MeSH
- ribonukleasa III * genetika metabolismus MeSH
- RNA interference * MeSH
- virus encefalomyokarditidy genetika imunologie MeSH
- virus lymfocytární choriomeningitidy imunologie genetika MeSH
- viry klíšťové encefalitidy genetika imunologie MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
UNLABELLED: In order to initiate an infection, viruses need to deliver their genomes into cells. This involves uncoating the genome and transporting it to the cytoplasm. The process of genome delivery is not well understood for nonenveloped viruses. We address this gap in our current knowledge by studying the uncoating of the nonenveloped human cardiovirus Saffold virus 3 (SAFV-3) of the family Picornaviridae SAFVs cause diseases ranging from gastrointestinal disorders to meningitis. We present a structure of a native SAFV-3 virion determined to 2.5 Å by X-ray crystallography and an 11-Å-resolution cryo-electron microscopy reconstruction of an "altered" particle that is primed for genome release. The altered particles are expanded relative to the native virus and contain pores in the capsid that might serve as channels for the release of VP4 subunits, N termini of VP1, and the RNA genome. Unlike in the related enteroviruses, pores in SAFV-3 are located roughly between the icosahedral 3- and 5-fold axes at an interface formed by two VP1 and one VP3 subunit. Furthermore, in native conditions many cardioviruses contain a disulfide bond formed by cysteines that are separated by just one residue. The disulfide bond is located in a surface loop of VP3. We determined the structure of the SAFV-3 virion in which the disulfide bonds are reduced. Disruption of the bond had minimal effect on the structure of the loop, but it increased the stability and decreased the infectivity of the virus. Therefore, compounds specifically disrupting or binding to the disulfide bond might limit SAFV infection. IMPORTANCE: A capsid assembled from viral proteins protects the virus genome during transmission from one cell to another. However, when a virus enters a cell the virus genome has to be released from the capsid in order to initiate infection. This process is not well understood for nonenveloped viruses. We address this gap in our current knowledge by studying the genome release of Human Saffold virus 3 Saffold viruses cause diseases ranging from gastrointestinal disorders to meningitis. We show that before the genome is released, the Saffold virus 3 particle expands, and holes form in the previously compact capsid. These holes serve as channels for the release of the genome and small capsid proteins VP4 that in related enteroviruses facilitate subsequent transport of the virus genome into the cell cytoplasm.
The aim of this study was to describe the frequency and distribution of Saffold virus in longitudinal stool samples from children, and test for association with development of persistent autoantibodies predictive of type 1 diabetes. A cohort of Norwegian children carrying the HLA genotype associated with highest risk of type 1 diabetes ("DR4-DQ8/DR3-DQ2") was followed with monthly stool samples from 3 to 35 months of age. Blood samples were tested for autoantibodies to insulin, glutamic acid decarboxylase65 and Islet Antigen-2. 2077 stool samples from 27 children with ≥ 2 repeatedly positive islet autoantibodies (cases), and 53 matched controls were analysed for Saffold virus genomic RNA by semi-quantitative real-time reverse transcriptase PCR. Saffold virus was found in 53 of 2077 (2.6%) samples, with similar proportions between cases (2.5%) and controls (2.6%). The probability of being infected by 3 years of age was 28% (95% CI 0.18-0.40). Viral quantities ranged from <1 to almost 105 copies/μl. Estimated odds ratio between islet autoimmunity and infection episodes prior to seroconversion was 1.98 (95% CI: 0.57-6.91, p = 0.29). Saffold virus had no statistically significant association with islet autoimmunity.
- MeSH
- autoprotilátky krev MeSH
- Cardiovirus izolace a purifikace MeSH
- diabetes mellitus 1. typu krev genetika imunologie MeSH
- feces virologie MeSH
- glutamát dekarboxyláza imunologie MeSH
- HLA-DQ antigeny genetika MeSH
- infekce viry z rodu Cardiovirus krev imunologie virologie MeSH
- inzulin imunologie MeSH
- kojenec MeSH
- lidé MeSH
- longitudinální studie MeSH
- předškolní dítě MeSH
- tyrosinfosfatasy receptorového typu, třída 8 imunologie MeSH
- virová nálož MeSH
- Check Tag
- kojenec MeSH
- lidé MeSH
- mužské pohlaví MeSH
- předškolní dítě MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- bakteriální polysacharidy aplikace a dávkování MeSH
- časové faktory MeSH
- endotoxiny aplikace a dávkování MeSH
- Escherichia coli MeSH
- induktory interferonů aplikace a dávkování MeSH
- injekce intraperitoneální MeSH
- interferony krev MeSH
- lipopolysacharidy aplikace a dávkování MeSH
- myši MeSH
- poly I-C aplikace a dávkování MeSH
- virové nemoci krev mortalita prevence a kontrola MeSH
- virus encefalomyokarditidy MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- MeSH
- biotest MeSH
- časové faktory MeSH
- cyklofosfamid farmakologie MeSH
- histologické techniky MeSH
- imunosupresiva farmakologie MeSH
- induktory interferonů aplikace a dávkování MeSH
- injekce intraperitoneální MeSH
- injekce subkutánní MeSH
- interferony krev MeSH
- kolifágy MeSH
- L buňky (buněčná linie) MeSH
- lymfatické uzliny patologie MeSH
- mononukleární fagocytární systém účinky léků MeSH
- mozek patologie MeSH
- myši MeSH
- RNA virová aplikace a dávkování farmakologie MeSH
- slezina patologie MeSH
- virus encefalomyokarditidy MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
