Project description:The natural maintenance cycles of many mosquito-borne pathogens require establishment of persistent non-lethal infections in the invertebrate host. The mechanism by which this occurs is not well understood, but we have previously shown that an antiviral response directed by small interfering RNAs (siRNAs) is important in modulating the pathogenesis of alphavirus infections in the mosquito. However, we report here that infection of mosquitoes with an alphavirus also triggers the production of another class of virus-derived small RNAs that exhibit many similarities to ping-pong-dependent piwi-interacting RNAs (piRNAs). However, unlike ping-pong-dependent piRNAs that have been described previously from repetitive elements or piRNA clusters, our work suggests production in the soma and a role for dsRNA in biogenesis. We also present evidence that suggests virus-derived piwi-like RNAs are capable of modulating the pathogenesis of alphavirus infections in dicer-2 null mutant mosquito cell lines defective in viral siRNA production. Overall, our results suggest that a non-canonical piRNA pathway is present in the soma of vector mosquitoes and may be acting redundantly to the siRNA pathway to target alphavirus replication. Comparison of virus derived small RNAs in several mosquito cell types
Project description:Encoded model contains complete kinetics of infection for coxsackievirus B3 (CVB3), a compact and fast-acting RNA virus. The model consists of separable, detailed modules describing viral binding-delivery, translation-replication, and encapsidation. Specific module activities are dampened by the type I interferon response to viral double-stranded RNAs (dsRNAs), which is itself disrupted by viral proteinases
Project description:The natural maintenance cycles of many mosquito-borne pathogens require establishment of persistent non-lethal infections in the invertebrate host. The mechanism by which this occurs is not well understood, but we have previously shown that an antiviral response directed by small interfering RNAs (siRNAs) is important in modulating the pathogenesis of alphavirus infections in the mosquito. However, we report here that infection of mosquitoes with an alphavirus also triggers the production of another class of virus-derived small RNAs that exhibit many similarities to ping-pong-dependent piwi-interacting RNAs (piRNAs). However, unlike ping-pong-dependent piRNAs that have been described previously from repetitive elements or piRNA clusters, our work suggests production in the soma and a role for dsRNA in biogenesis. We also present evidence that suggests virus-derived piwi-like RNAs are capable of modulating the pathogenesis of alphavirus infections in dicer-2 null mutant mosquito cell lines defective in viral siRNA production. Overall, our results suggest that a non-canonical piRNA pathway is present in the soma of vector mosquitoes and may be acting redundantly to the siRNA pathway to target alphavirus replication.
Project description:A time course of infection of the alphavirus Sindbis virus (SINV) was used to investigate the presence of viral specific vsRNA and the changes in miRNAs profiles in human embryonic kidney 293 cells (HEK293) by high throughput DNA sequencing. Deep sequencing of small RNAs early in SINV infection (4 and 6 hpi) showed low abundance (0.8%) of viral specific RNAs (vsRNAs) , with a random uniform distribution not typical of Dicer products, suggesting they arise from non-specific degradation. Sequencing showed little variation of cellular microRNAs (miRNAs) at 4 and 6 hpi compared to uninfected cells. Twelve miRNAs exhibiting some minor differential expression by sequencing, showed insignificant modulation by Northern blot analysis.
Project description:RNA interference (RNAi) functions as an antiviral immune response in plants and invertebrates, whereas mammalian RNAi response has been found so far only in undifferentiated cells and in differentiated cells inactive in interferon (IFN) system or in infections with viruses disabling viral suppressors of RNAi (VSRs), thereby leading to question the physiological importance of the RNAi pathway in mammals. Here, we identified that wild-type Semliki Forest virus (SFV), a prototypic alphavirus, triggered the Dicer-dependent production of abundant viral (v)siRNAs in different mammalian somatic cells in the presence of VSR. These vsiRNAs were produced from viral dsRNA replicative intermediates, almost exclusively located at the 5’ termini of the viral genome, and loaded into AGO, and they were fully active in slicing cognate viral RNAs. Besides, Sindbis virus, another alphavirus, also induced vsiRNA generation in mammalian somatic cells. AGO2 deficiency increased SFV and SINV replication, while enoxacin, a known RNAi enhancer that functions at post steps of siRNA production, efficiently reduced viral replication. The nucleotide sequence at the 5’ termini of SFV and SINV genome is conserved among the Old World alphaviruses, and mutating the conserved sequences resulted in the recombinant SFV being deficient in vsiRNA production and irresponsive to antiviral RNAi. SFV infection also enabled the production of abundant vsiRNAs and antiviral RNAi in IFN-competent adult mice, and importantly, enhanced RNAi by enoxacin protected adult mice from lethal SFV challenge and reduced the virus-induced neuropathogenesis in the central neuron system. Overall, our findings provide evidence that mammalian antiviral RNAi is active in differentiated cells and adult mice with intact IFN response even in the presence of VSR and present a therapeutic strategy against alphaviruses that include many important emerging and reemerging human pathogens.
Project description:A time course of infection of the alphavirus Sindbis virus (SINV) was used to investigate the presence of viral specific vsRNA and the changes in miRNAs profiles in human embryonic kidney 293 cells (HEK293) by high throughput DNA sequencing. Deep sequencing of small RNAs early in SINV infection (4 and 6 hpi) showed low abundance (0.8%) of viral specific RNAs (vsRNAs) , with a random uniform distribution not typical of Dicer products, suggesting they arise from non-specific degradation. Sequencing showed little variation of cellular microRNAs (miRNAs) at 4 and 6 hpi compared to uninfected cells. Twelve miRNAs exhibiting some minor differential expression by sequencing, showed insignificant modulation by Northern blot analysis. RNA was isolated from mock infected and SINV inoculated HEK 293 cells at 4hpi and 6hpi cDNA libraries were generated for the small RNA (sRNA) content of the cells and sequenced using Illumina GA II, which yielded between 29.1M and 30.5M reads per sample
Project description:N6-methyladenosine (m6A) is the most abundant internal RNA modification catalyzed by host RNA methyltransferases. As obligate intracellular parasites, many viruses acquire m6A methylation in their RNAs. However, the biological functions of viral m6A methylation are poorly understood. Here, we found that viral m6A methylation serves as a molecular marker for host innate immunity to discriminate self from nonself RNA and that this novel biological function of viral m6A methylation is universally conserved in non-segmented negative-sense (NNS) RNA viruses. Using m6A methyltransferase (METTL3)-knockout cells, we produced m6A-deficient virion RNA from the representative members of the families Pneumoviridae, Paramyxoviridae, and Rhabdoviridae and found that these m6A-deficient viral RNAs triggered significantly higher levels of type I interferon compared to the m6A-sufficient viral RNAs, in a RIG-I dependent manner. Reconstitution of the RIG-I pathway revealed that m6A-deficient virion RNA induced higher expression of RIG-I, bound to RIG-I more efficiently, enhanced RIG-I ubiquitination, and facilitated RIG-I conformational rearrangement and oligomerization. Furthermore, the m6A binding protein YTHDF2 sequesters m6A-sufficient virion RNA which suppresses type I interferon signaling pathway. Collectively, our results suggest that NNS RNA viruses acquire m6A in viral RNA as a common strategy to evade host innate immunity.
Project description:N6-methyladenosine (m6A) is the most abundant internal RNA modification catalyzed by host RNA methyltransferases. As obligate intracellular parasites, many viruses acquire m6A methylation in their RNAs. However, the biological functions of viral m6A methylation are poorly understood. Here, we found that viral m6A methylation serves as a molecular marker for host innate immunity to discriminate self from nonself RNA and that this novel biological function of viral m6A methylation is universally conserved in non-segmented negative-sense (NNS) RNA viruses. Using m6A methyltransferase (METTL3)-knockout cells, we produced m6A-deficient virion RNA from the representative members of the families Pneumoviridae, Paramyxoviridae, and Rhabdoviridae and found that these m6A-deficient viral RNAs triggered significantly higher levels of type I interferon compared to the m6A-sufficient viral RNAs, in a RIG-I dependent manner. Reconstitution of the RIG-I pathway revealed that m6A-deficient virion RNA induced higher expression of RIG-I, bound to RIG-I more efficiently, enhanced RIG-I ubiquitination, and facilitated RIG-I conformational rearrangement and oligomerization. Furthermore, the m6A binding protein YTHDF2 sequesters m6A-sufficient virion RNA which suppresses type I interferon signaling pathway. Collectively, our results suggest that NNS RNA viruses acquire m6A in viral RNA as a common strategy to evade host innate immunity.
2021-01-16 | GSE164882 | GEO
Project description:Type I interferon regulates the expression of long non-coding RNAs