Identification of a mutated BHK-21 cell line that became less susceptible to Japanese encephalitis virus infection

Molecular cloning and characterization of duck Annexin A2 and its effect on DTMUV replication

Annexin A2 (ANXA2) is a multifaceted protein implicated in various stages of viral infections, particularly in envelope virus replication through mechanisms such as endocytosis and exocytosis. This study delves into the characterization and functional dynamics of duck ANXA2 (duANXA2). We successfully cloned the full-length coding sequence of duANXA2 and conducted a detailed structural analysis. The open reading frame (ORF) of duANXA2 is 1020 bp, encoding 339 amino acids and featuring 4 conserved domains. Phylogenetic tree analysis indicates that duANXA2 is most closely related to Gallus gallus, with significantly lesser homology to fish species. We evaluated the tissue-specific expression of duANXA2 in healthy ducks, noting its ubiquitous presence but varying expression levels across different organs, with notably high expression in the esophagus and immune organs. Upon infecting duck embryo fibroblast (DEF) cells with the duck Tembusu virus (DTMUV), a flavivirus causing ducks substantial mortality and a dramatic decline in egg production, we observed a pronounced upregulation of duANXA2. Functional assays demonstrated that overexpression of duANXA2 in DEF cells augments DTMUV replication, while its interference markedly reduces DTMUV replication. These findings underscore the role of duANXA2 as a facilitator of DTMUV replication, presenting it as a potential target for therapeutic intervention in managing DTMUV infections.

Allosteric Activator-Regulated CRISPR/Cas12a System Enables Biosensing and Imaging of Intracellular Endogenous and Exogenous Targets

Sensors designed based on the trans-cleavage activity of CRISPR/Cas12a systems have opened up a new era in the field of biosensing. The current design of CRISPR/Cas12-based sensors in the "on-off-on" mode mainly focuses on programming the activator strand (AS) to indirectly switch the trans-cleavage activity of Cas12a in response to target information. However, this design usually requires the help of additional auxiliary probes to keep the activator strand in an initially "blocked" state. The length design and dosage of the auxiliary probe need to be strictly optimized to ensure the lowest background and the best signal-to-noise ratio. This will inevitably increase the experiment complexity. To solve this problem, we propose using AS after the "RESET" effect to directly regulate the Cas12a enzymatic activity. Initially, the activator strand was rationally designed to be embedded in a hairpin structure to deprive its ability to activate the CRISPR/Cas12a system. When the target is present, target-mediated strand displacement causes the conformation change in the AS, the hairpin structure is opened, and the CRISPR/Cas12a system is reactivated; the switchable structure of AS can be used to regulate the degree of activation of Cas12a according to the target concentration. Due to the advantages of low background and stability, the CRISPR/Cas12a-based strategy can not only image endogenous biomarkers (miR-21) in living cells but also enable long-term and accurate imaging analysis of the process of exogenous virus invasion of cells. Release and replication of virus genome in host cells are indispensable hallmark events of cell infection by virus; sensitive monitoring of them is of great significance to revealing virus infection mechanism and defending against viral diseases.

Antiviral and anti-inflammatory activity of novel belladonna formulation against Japanese encephalitis virus via inhibition of p65 nuclear translocation and TNF-α mediated NF-kB signaling

Japanese encephalitis (JE) is a mosquito-borne flavivirus infection, a major cause of viral encephalitis in South-East Asia with a CFR of ~30% and no specific treatment. Therefore, a novel belladonna formulation (BCT) was prepared and its antiviral and anti-inflammatory activity was elucidated during Japanese encephalitis virus (JEV) infection. Anti-JEV role of BCT was investigated aiming to prevent the infection in the peripheral immune cells. Antiviral activity of BCT was evaluated by plaque reduction assay, cell survival and apoptosis assay. BCT-mediated reduction in JEV-envelope expression was measured by indirect immunofluorescence, RT-PCR and Western blot assays. NF-κB expression and p65 nuclear translocation assays were determined to explore the mechanism of the action of BCT. TNF-α level was measured to evaluate the anti-inflammatory role of BCT during JEV infection. Consequently, molecular docking was performed with the TRAF2-TRADD complex. Our data suggested that BCT treatment reduces the JEV-plaque formation, JEV-induced cytopathic effects and increases cell survival. The antiviral effect of BCT was confirmed by reduction in the JEV-envelope protein expression. Moreover, BCT treatment and prevents the NF-κB activation via preventing the nuclear translocation of p65 and reduces the TNF-α levels. Our molecular docking analysis suggested that belladonna alkaloids interfere with the TRAF2-TRADD complex that results in inhibition of TNF-induced NF-κB signaling. For the first time, our data suggested that BCT reduces JEV expression and interferes with TNF-induced NF-κB signaling, thereby increasing cell survival via preventing the p65 nuclear translocation and may be used for the treatment and prevention of JE.Abbreviation: CFR: Case fatality rate; CAM: Complementary and alternative medicines; COX-2: Cyclooxygenase-2; IκB: Inhibitor kappa B; JE: Japanese encephalitis; JEV: Japanese encephalitis virus; NF-κB: Nuclear factor kappa-light-chain-enhancer of activated B cells; ORF: Open reading frame; TNFR: Tumor necrosis factor receptor; TNF-α: Tumor necrosis factor-α; TRADD: TNFR1-associated death domain protein; TRAF2: TNF Receptor Associated Factor 2.

Heat shock protein 90β in the Vero cell membrane binds Japanese encephalitis virus

The pathogenesis of Japanese encephalitis virus (JEV) is complex and unclearly defined, and in particular, the effects of the JEV receptor (JEVR) on diverse susceptible cells are elusive. In contrast to previous studies investigating JEVR in rodent or mosquito cells, in this study, we used primate Vero cells instead. We noted that few novel proteins co‑immunoprecipitated with JEV, and discovered that one of these was heat shock protein 90β (HSP90β), which was probed by mass spectrometry with the highest score of 60.3 after questing the monkey and human protein databases. The specific HSP90β‑JEV binding was confirmed by western blot analysis under non‑reducing conditions, and this was significantly inhibited by an anti‑human HSP90β monoclonal antibody in a dose‑dependent manner, as shown by immunofluorescence assay and flow cytometry. In addition, the results of confocal laser scanning microscopic examination demonstrated that the HSP90β‑JEV binding occurred on the Vero cell surface. Finally, JEV progeny yields determined by plaque assay were also markedly decreased in siRNA‑treated Vero cells, particularly at 24 and 36 h post‑infection. Thus, our data indicate that HSP90β is a binding receptor for JEV in Vero cells.