Preparation of long single-strand DNA concatemers for high-level fluorescence in situ hybridization.

Fluorescence in situ hybridization (FISH) is a powerful tool to visualize transcripts in fixed cells and tissues. Despite the recent advances in FISH detection methods, it remains challenging to achieve high-level FISH imaging with a simple workflow. Here, we introduce a method to prepare long single-strand DNA concatemers (lssDNAc) through a controllable rolling-circle amplification (CRCA). Prepared lssDNAcs are used to develop AmpFISH workflows. In addition, we present its applications in different scenarios. AmpFISH shows the following advantages: 1) enhanced FISH signal-to-noise ratio (SNR) up to 160-fold compared with single-molecule FISH; 2) simultaneous detection of FISH signals and fluorescent proteins or immunofluorescence (IF) in tissues; 3) simple workflows; and 4) cost-efficiency. In brief, AmpFISH provides convenient and versatile tools for sensitive RNA/DNA detection and to gain useful information on cellular molecules using simple workflows.

Antiviral Effects of Novel 2-Benzoxyl-Phenylpyridine Derivatives.

Coxsackievirus B3 (CVB3) is the most common cause of acute and chronic viral myocarditis, primarily in children, while human adenovirus infections represent a significant cause of morbidity and mortality worldwide, in people of all ages. A series of novel 2-benzoxyl-phenylpyridine derivatives were evaluated for their potential antiviral activities against CVB3 and adenovirus type 7 (ADV7). Preliminary assays indicated that some of these compounds exhibited excellent antiviral effects on both CVB3 and ADV7 viruses; they could effectively inhibit virus-induced cytopathic effects, reduce viral progeny yields, and had similar or superior antiviral activities compared with the control drug, ribavirin. Further, these compounds targeted the early stages of CVB3 replication in cells, including viral RNA replication and protein synthesis, rather than inactivating the virus directly, inhibiting virus adsorption/entry, or affecting viral release from cells. Our data demonstrate that the tested 2-benzoxyl-phenylpyridine derivatives are effective inhibitors of CVB3 and ADV7, raising the possibility that these compounds might be feasible candidates for anti-viral agents.

Transcriptomic analysis of cells in response to EV71 infection and 2Apro as a trigger for apoptosis via TXNIP gene.

BACKGROUND: Enterovirus 71 (EV71) is the main pathogen of hand-foot-mouth disease (HFMD) and sometimes causes several neurological complications. However, the underlying mechanism of the host response to the virus infection remains unclear. OBJECTIVE: To reveal the cell-specific transcriptional response of cultured RD cells following infection with EV71, and better understand the molecular mechanisms of virus-host interactions. METHODS: The RD cells were infected with or without EV71 for 24 h, and then transcriptome sequencing and qRT-PCR were performed to analyze the transcriptome difference of functional genes. RESULTS: More than 15000 genes were identified in transcriptome sequencing. In comparison with uninfected RD cells, 329 DEGs were identified in cells infected with EV71. GO and KEGG pathway enrichment analysis showed that most of the DEGs were related to DNA binding, transcriptional regulation, immune response and inflammatory response, apoptosis inducing factors and enriched in JAK-STAT and MAPK signaling pathways. TXNIP (thioredoxin-interacting protein) gene was further demonstrated to play an important role participating in cellular apoptosis induced by EV71, and the apoptosis and death mediated by TXNIP during EV71 infection was triggered by viral 2A protease (2Apro), not 3C protease (3Cpro). CONCLUSION: Our study demonstrated that RD cells have a significant response to EV71 infection, including immune response and apoptosis. 2Apro might be a key inducer relative to the cellular apoptosis and death mediated by TXNIP during EV71 infection. These data would contribute to preferably understand the process at the molecular level and provide theoretical foundation for diagnosis and treatment of EV71-related diseases.

Inhibition of enterovirus 71 replication and viral 3C protease by quercetin.

BACKGROUND: Enterovirus 71 (EV71) is one of the major causative agents of hand, foot, and mouth disease (HFMD), which is sometimes associated with severe central nervous system disease in children. There is currently no specific medication for EV71 infection. Quercetin, one of the most widely distributed flavonoids in plants, has been demonstrated to inhibit various viral infections. However, investigation of the anti-EV71 mechanism has not been reported to date. METHODS: The anti-EV71 activity of quercetin was evaluated by phenotype screening, determining the cytopathic effect (CPE) and EV71-induced cells apoptosis. The effects on EV71 replication were evaluated further by determining virus yield, viral RNA synthesis and protein expression, respectively. The mechanism of action against EV71 was determined from the effective stage and time-of-addition assays. The possible inhibitory functions of quercetin via viral 2Apro, 3Cpro or 3Dpol were tested. The interaction between EV71 3Cpro and quercetin was predicted and calculated by molecular docking. RESULTS: Quercetin inhibited EV71-mediated cytopathogenic effects, reduced EV71 progeny yields, and prevented EV71-induced apoptosis with low cytotoxicity. Investigation of the underlying mechanism of action revealed that quercetin exhibited a preventive effect against EV71 infection and inhibited viral adsorption. Moreover, quercetin mediated its powerful therapeutic effects primarily by blocking the early post-attachment stage of viral infection. Further experiments demonstrated that quercetin potently inhibited the activity of the EV71 protease, 3Cpro, blocking viral replication, but not the activity of the protease, 2Apro, or the RNA polymerase, 3Dpol. Modeling of the molecular binding of the 3Cpro-quercetin complex revealed that quercetin was predicted to insert into the substrate-binding pocket of EV71 3Cpro, blocking substrate recognition and thereby inhibiting EV71 3Cpro activity. CONCLUSIONS: Quercetin can effectively prevent EV71-induced cell injury with low toxicity to host cells. Quercetin may act in more than one way to deter viral infection, exhibiting some preventive and a powerful therapeutic effect against EV71. Further, quercetin potently inhibits EV71 3Cpro activity, thereby blocking EV71 replication.