Viral RNA-dependent RNA polymerases (RdRps) are a target for broad-spectrum antiviral therapeutic agents. Recently, we demonstrated that incorporation of the T-1106 triphosphate, a ...pyrazine-carboxamide ribonucleotide, into nascent RNA increases pausing and backtracking by the poliovirus RdRp. Here, by monitoring enterovirus A-71 RdRp dynamics during RNA synthesis using magnetic tweezers, we identify the “backtracked” state as an intermediate used by the RdRp for copy-back RNA synthesis and homologous recombination. Cell-based assays and RNA sequencing (RNA-seq) experiments further demonstrate that the pyrazine-carboxamide ribonucleotide stimulates these processes during infection. These results suggest that pyrazine-carboxamide ribonucleotides do not induce lethal mutagenesis or chain termination but function by promoting template switching and formation of defective viral genomes. We conclude that RdRp-catalyzed intra- and intermolecular template switching can be induced by pyrazine-carboxamide ribonucleotides, defining an additional mechanistic class of antiviral ribonucleotides with potential for broad-spectrum activity.
Display omitted
•RdRp “backtracked” state is an intermediate for template switching•Intra- and intermolecular template switching use the same “backtracked” intermediate•Pyrazine-carboxamide nucleotides dysregulate recombination, increasing defective genomes•Alternative mechanistic class and target of antiviral nucleotides are revealed
Using a multidisciplinary approach, Janissen et al. demonstrate that intra- and intermolecular recombination events in enteroviruses originate from a “backtracked” polymerase intermediate. Pyrazine-carboxamide ribonucleotides promote formation of this intermediate, revealing the antiviral nature of chemically induced recombination and a unique mechanistic class of antiviral ribonucleotides.
This systematic review and meta-analysis aimed to assess the efficacy and safety of cupping therapy in patients with metabolic syndrome (MetS).
This systematic review focused on patients with MetS ...and included randomized controlled trials (RCTs) that compared the effects of cupping therapy with control groups. A total of 12 electronic databases were searched from inception until February 03, 2023. The main outcome after the meta-analysis was waist circumference; the others included anthropometric variables, blood pressure, lipid profile, fasting blood glucose level, and high-sensitivity C-reactive protein level. The incidence of adverse events and the follow-up courses were also evaluated. Risk of bias (ROB) was evaluated using ROB 2.0 from the Cochrane Handbook.
This systematic review included five studies involving 489 patients. Some risks of bias were also identified. The meta-analysis revealed a statistically significance in waist circumference (MD = -6.07, 95% CI: -8.44 to -3.71, P < .001, I2 = 61%, τ2 = 3.4), body weight (MD = -2.46, 95% CI: -4.25 to -0.68, P = .007, I2 = 0%, τ2 = 0) and body mass index (MD = -1.26, 95% CI: -2.11 to -0.40, P = .004, I2 = 0%, τ2 = 0) between the cupping therapy and control groups. However, there were no significant results in total fat percentage and blood pressure values. Regarding biochemical markers, cupping significantly lowered the concentration of low-density lipoprotein cholesterol (MD = -3.98, 95% CI: -6.99 to -0.96, P = .010, I2 = 0%, τ2 = 0) but had no significant effect on total cholesterol, triglyceride, high-density lipoprotein cholesterol, fasting blood glucose, and high-sensitivity C-reactive protein. 3 RCTs reported no adverse events.
Despite some ROB and low to substantial heterogeneity of the included studies, cupping therapy can be considered a safe and effective complementary intervention for reducing waist circumference, body weight, body mass index, and low-density lipoprotein cholesterol in patients with MetS. In the future, well-designed, high-quality, rigorous methodology, and long-term RCTs in this population are required to assess the efficacy and safety of cupping therapy.
Enterovirus 71 (EV71) is a picornavirus that can cause severe neurological complications in children. Like other picornaviruses, the genomic RNA of EV71 contains a long 5' untranslated region (UTR). ...Cellular proteins interact with the EV71 5' UTR, and these interactions are important for virus replication. Using an RNA pull-down assay and proteomics approaches, this study identified the heterogeneous nuclear ribonucleoprotein K (hnRNP K) as one of the EV71 5' UTR-associated proteins. The interaction between hnRNP K and the 5' UTR was further confirmed by mapping the interaction regions to stem-loops I-II and IV in the 5' UTR. During EV71 infection, hnRNP K was enriched in the cytoplasm where virus replication occurs, whereas hnRNP K was localized in the nucleus in mock-infected cells. Viral yields were found to be significantly lower in hnRNP K knockdown cells and viral RNA synthesis was delayed in hnRNP K knockdown cells in comparison with negative-control cells treated with small interfering RNA. These results suggest that hnRNP K interacts with the EV71 5' UTR and participates in virus replication.
Enterovirus 71 (EV71) is associated with severe neurological disorders in children, and has been implicated as the infectious agent in several large-scale outbreaks with mortalities. Upon infection, ...the viral RNA is translated in a cap-independent manner to yield a large polyprotein precursor. This mechanism relies on the presence of an internal ribosome entry site (IRES) element within the 5′-untranslated region. Virus-host interactions in EV71-infected cells are crucial in assisting this process. We identified a novel positive IRES trans-acting factor, far upstream element binding protein 1 (FBP1). Using binding assays, we mapped the RNA determinants within the EV71 IRES responsible for FBP1 binding and mapped the protein domains involved in this interaction. We also demonstrated that during EV71 infection, the nuclear protein FBP1 is enriched in cytoplasm where viral replication occurs. Moreover, we showed that FBP1 acts as a positive regulator of EV71 replication by competing with negative ITAF for EV71 IRES binding. These new findings may provide a route to new anti-viral therapy.
The roles of virus-derived small RNAs (vsRNAs) have been studied in plants and insects. However, the generation and function of small RNAs from cytoplasmic RNA viruses in mammalian cells remain ...unexplored. This study describes four vsRNAs that were detected in enterovirus 71-infected cells using next-generation sequencing and northern blots. Viral infection produced substantial levels (>10(5) copy numbers per cell) of vsRNA1, one of the four vsRNAs. We also demonstrated that Dicer is involved in vsRNA1 generation in infected cells. vsRNA1 overexpression inhibited viral translation and internal ribosomal entry site (IRES) activity in infected cells. Conversely, blocking vsRNA1 enhanced viral yield and viral protein synthesis. We also present evidence that vsRNA1 targets stem-loop II of the viral 5' untranslated region and inhibits the activity of the IRES through this sequence-specific targeting. Our study demonstrates the ability of a cytoplasmic RNA virus to generate functional vsRNA in mammalian cells. In addition, we also demonstrate a potential novel mechanism for a positive-stranded RNA virus to regulate viral translation: generating a vsRNA that targets the IRES.
Enteroviruses (EVs) are common human pathogens that are associated with numerous disease symptoms in many organ systems of the body. Although EV infections commonly cause mild or non-symptomatic ...illness, some of them are associated with severe diseases such as CNS complications. The current absence of effective vaccines for most viral infection and no available antiviral drugs for the treatment of EVs highlight the urgency and significance of developing antiviral agents. Several key steps in the viral life cycle are potential targets for blocking viral replication. This article reviews recent studies of antiviral developments for EVs based on various molecular targets that interrupt viral attachment, viral translation, polyprotein processing and RNA replication.
Frequent outbreaks of enterovirus A71 (EVA71) occur in the Asia-Pacific area, and these are closely associated with severe neurological symptoms in young children. No effective antiviral therapy is ...currently available for the treatment of EVA71 infection. The development of monoclonal antibodies (mAbs) has demonstrated promise as a novel therapy for the prevention and treatment of infectious diseases. Several medical conditions have been treated using bispecific or multi-specific antibodies that recognize two or more distinct epitopes simultaneously. However, bispecific or multi-specific antibodies often encounter protein expression and product stability problems. In this study, we developed an IgG-like bispecific antibody (E18-F1) comprising two anti-EVA71 antibodies: E18 mAb and llama-derived F1 single-domain antibody. E18-F1 was demonstrated to exhibit superior binding affinity and antiviral activity compared with E18 or F1. Additionally, E18-F1 not only improved survival rate, but also reduced clinical signs in human SCARB2 receptor (hSCARB2) transgenic mice challenged with a lethal dose of EVA71. Altogether, our results reveal that E18-F1 is a simple format bispecific antibody with promising antiviral activity for EVA71.
•We develop a novel bispecific antibody platform based on a fusion strategy at the C-terminal of the light chain.•A two-in-one antibody with enhanced antiviral function based on engaging distinct mechanisms.•The design provides a novel single domain antibody armed IgG-based bispecific antibody as an alternative approach.
Enteroviruses, which may cause neurological complications, have become a public health threat worldwide in recent years. Interactions between cellular proteins and enteroviral proteins could ...interfere with cellular biological processes to facilitate viral replication in infected cells. Enteroviral RNA-dependent RNA polymerase (RdRP), known as 3D protein, mainly functions as a replicase for viral RNA synthesis in infected cells. However, the 3D protein encoded by enterovirus A71 (EV-A71) could also interact with several cellular proteins to regulate cellular events and responses during infection. To globally investigate the functions of the EV-A71 3D protein in regulating biological processes in host cells, we performed immunoprecipitation coupled with liquid chromatography−tandem mass spectrometry (LC-MS/MS) to identify host proteins that may associate with the 3D protein. We found that the 3D protein interacts with factors involved in translation-related biological processes, including ribosomal proteins. In addition, polysome profiling analysis showed that the 3D protein cosediments with small and large subunits of ribosomes. We further discovered that the EV-A71 3D protein could enhance EV-A71 internal ribosome entry site (IRES)-dependent translation as well as cap-dependent translation. Collectively, this research demonstrated that the RNA polymerase encoded by EV-A71 could join a functional ribosomal complex and positively regulate viral and host translation.
The susceptibility of five cell lines, RD, MRC-5, MK-2, Hep-2 and A549, for various serotypes of human enteroviruses was evaluated. RD cells were susceptible to most serotypes of enteroviruses, ...especially for human enterovirus A. Consequently, a high prevalence of human enterovirus A in Taiwan may reflect the relative importance of RD cells in the clinical virology laboratory. However, susceptibilities of RD cells to coxsackievirus A9 and A24, and echovirus 9 and 11 were exceptionally low. Alternatively, MRC-5 or MK-2 cells can improve the isolation of these four enteroviruses.
Pyridyl imidazolidinone is a novel class of capsid binder which can inhibit enterovirus 71 (EV71). In this study, we tested the susceptibility of six recombinant viruses with different single-site ...mutations in VP1. Eleven modified pyridyl imidazolidinones were synthesized and used to probe the interaction between these compounds and the EV71 VP1 protein. We found that the D31N or E98K mutant viruses were susceptible to bulkier compounds, which suggested that mutations at these two sites in VP1 may widen the hydrophobic pocket of VP1, allowing bulkier compounds to enter and interfere VP1-receptor binding. Additionally, the Y116H mutant was more resistant to pyridyl imidazolidinone compounds containing a methyl group in the central position of the hydrophobic linker. When a trifluoromethyl group was substituted for the methyl group in the middle of the linker chain, the inhibitory effect was totally abolished in the Y116H mutant, suggesting that the interaction between Tyr (Y) 116 of VP1 and the central position of the linker chain of pyridyl imidazolodinone is very important for drug efficacy. A V192M mutant was resistant to most of the derivatives, indicating that residue 192 is a key mutation for resistance to pyridyl imidazolidinone.
PDF
