Inhibition Of Viral Replication Research Articles

Argonaute-independent, Dicer-dependent antiviral defense against RNA viruses

Antiviral RNA interference (RNAi) is conserved from yeasts to mammals. Dicer recognizes and cleaves virus-derived double-stranded RNA (dsRNA) and/or structured single-stranded RNA (ssRNA) into small-interfering RNAs, which guide effector Argonaute to homologous viral RNAs for digestion and inhibit virus replication. Thus, Argonaute is believed to be essential for antiviral RNAi. Here, we show Argonaute-independent, Dicer-dependent antiviral defense against dsRNA viruses using Cryphonectria parasitica (chestnut blight fungus), which is a model filamentous ascomycetous fungus and hosts a variety of viruses. The fungus has two dicer-like genes (dcl1 and dcl2) and four argonaute-like genes (agl1 to agl4). We prepared a suite of single to quadruple agl knockout mutants with or without dcl disruption. We tested these mutants for antiviral activities against diverse dsRNA viruses and ssRNA viruses. Although both DCL2 and AGL2 worked as antiviral players against some RNA viruses, DCL2 without argonaute was sufficient to block the replication of other RNA viruses. Overall, these results indicate the existence of a Dicer-alone defense and different degrees of susceptibility to it among RNA viruses. We discuss what determines the great difference in susceptibility to the Dicer-only defense.

Exploring Cannabinoids as Potential Inhibitors of SARS-CoV-2 Papain-like Protease: Insights from Computational Analysis and Molecular Dynamics Simulations.

The emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has triggered a global COVID-19 pandemic, challenging healthcare systems worldwide. Effective therapeutic strategies against this novel coronavirus remain limited, underscoring the urgent need for innovative approaches. The present research investigates the potential of cannabis compounds as therapeutic agents against SARS-CoV-2 through their interaction with the virus's papain-like protease (PLpro) protein, a crucial element in viral replication and immune evasion. Computational methods, including molecular docking and molecular dynamics (MD) simulations, were employed to screen cannabis compounds against PLpro and analyze their binding mechanisms and interaction patterns. The results showed cannabinoids with binding affinities ranging from -6.1 kcal/mol to -4.6 kcal/mol, forming interactions with PLpro. Notably, Cannabigerolic and Cannabidiolic acids exhibited strong binding contacts with critical residues in PLpro's active region, indicating their potential as viral replication inhibitors. MD simulations revealed the dynamic behavior of cannabinoid-PLpro complexes, highlighting stable binding conformations and conformational changes over time. These findings shed light on the mechanisms underlying cannabis interaction with SARS-CoV-2 PLpro, aiding in the rational design of antiviral therapies. Future research will focus on experimental validation, optimizing binding affinity and selectivity, and preclinical assessments to develop effective treatments against COVID-19.

Altered gut microbiota is associated with the formation of occult hepatitis B virus infection.

Hepatitis B virus (HBV), a common blood transmission pathogen worldwide, can lead to viral hepatitis, cirrhosis, liver cancer, and other liver diseases. In particular, occult hepatitis B virus infection (OBI) may be caused by an immune response leading to suppressed virus replication. Gut microbiota can change the immunity status of the human body and, therefore, affect the replication of HBV. Thus, to identify whether there are differences in gut microbiota between HBV carriers and OBI carriers, we collected fecal samples from 18 HBV carriers, 24 OBI blood donors, and also 20 healthy blood donors as negative control. After 16S sequencing, we found that the abundance of Faecalibacterium was significantly reduced in samples from OBI blood donors compared with those from healthy blood donors. Compared with samples from HBV carriers, the samples from OBI blood donors had a significantly increased abundance of Subdoligranulum, which might stimulate immune activation, thus inhibiting HBV replication and contributing to the formation of occult infection. Our findings revealed the potential role of gut microbiota in the formation of OBI and further provided a novel strategy for the treatment of HBV infection.IMPORTANCEOccult hepatitis B virus infection (OBI) is a special form of hepatitis B virus infection with hepatitis B surface antigen (HBsAg) positive and hepatitis B virus (HBV) DNA negative. Gut microbiota may contribute to the immune response leading to suppressed virus replication and, thus, participates in the development of OBI. The study on gut microbiota of OBI blood donors provides novel data considerably advancing our understanding of the immune mechanism for the determination of occult hepatitis B virus infection, which is helpful for improving the strategy of the treatment of HBV infection.

Antiviral Activity of Kappaphycus alvarezii Seaweed against ZIKV.

Zika virus (ZIKV) is a flavivirus transmitted through the bites of infected Aedes mosquitoes. These viruses can also be transmitted through sexual contact, vertical transmission, and possibly transfusion. Most cases are asymptomatic, but symptoms can include rash, conjunctivitis, fever, and arthralgia, which are characteristic of other arboviruses. Zika infection can lead to complications such as microcephaly, miscarriage, brain abnormalities, and Guillain-Barré syndrome (GBS). The aim is to determine the inhibitory potential of the algae Kappaphycus alvarezii (K. alvarezii) on ZIKV replication. Cytotoxicity experiments were performed using Vero cells to determine the CC50, and ZIKV replication inhibition assays (ATCC® VR-1839™) were conducted to determine the EC50. The mechanism of action was also studied to assess any synergistic effect with Ribavirin. K. alvarezii demonstrated low toxicity with a CC50 of 423 μg/mL and a potent effect on ZIKV replication with an EC50 of 0.65 μg/mL and a Selectivity Index (SI) of 651, indicating the extract's safety. Virucidal effect assays were carried out to evaluate the possible mechanism of action, and the compound addition time was studied, showing the potential to delay the treatment of infected cells by up to 6 hours. A potential synergistic effect was observed when K. alvarezii extract was combined with suboptimal concentrations of Ribavirin, resulting in 99% inhibition of viral replication. Our data demonstrate the significant potential of K. alvarezii extract and highlight the need for further studies to investigate its mechanism of action. We propose this extract as a potential anti-Zika compound.

Aberrant RNA polymerase initiation and processivity on the genome of a herpes simplex virus 1 mutant lacking ICP27.

Within the first 15 minutes of infection, herpes simplex virus 1 immediate early proteins repurpose cellular RNA polymerase (Pol II) for viral transcription. An important role of the viral-infected cell protein 27 (ICP27) is to facilitate viral pre-mRNA processing and export viral mRNA to the cytoplasm. Here, we use precision nuclear run-on followed by deep sequencing (PRO-seq) to characterize transcription of a viral ICP27 null mutant. At 1.5 and 3 hours post infection (hpi), we observed increased total levels of Pol II on the mutant viral genome and accumulation of Pol II downstream of poly A sites indicating increased levels of initiation and processivity. By 6 hpi, Pol II accumulation on specific mutant viral genes was higher than that on wild-type virus either at or upstream of poly A signals, depending on the gene. The PRO-seq profile of the ICP27 mutant on late genes at 6 hpi was similar but not identical to that caused by treatment with flavopiridol, a known inhibitor of RNA processivity. This pattern was different from PRO-seq profiles of other α gene mutants and upon inhibition of viral DNA replication with PAA. Together, these results indicate that ICP27 contributes to the repression of aberrant viral transcription at 1.5 and 3 hpi by inhibiting initiation and decreasing RNA processivity. However, ICP27 is needed to enhance processivity on most late genes by 6 hpi in a mechanism distinguishable from its role in viral DNA replication.IMPORTANCEWe developed and validated the use of a processivity index for precision nuclear run-on followed by deep sequencing data. The processivity index calculations confirm infected cell protein 27 (ICP27) induces downstream of transcription termination on certain host genes. The processivity indices and whole gene probe data implicate ICP27 in transient immediate early gene-mediated repression, a process that also requires ICP4, ICP22, and ICP0. The data indicate that ICP27 directly or indirectly regulates RNA polymerase (Pol II) initiation and processivity on specific genes at specific times post infection. These observations support specific and varied roles for ICP27 in regulating Pol II activity on viral genes in addition to its known roles in post transcriptional mRNA processing and export.

Inhibition of mRNA nuclear export promotes SARS-CoV-2 pathogenesis

The nonstructural protein 1 (Nsp1) of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) is a virulence factor that targets multiple cellular pathways to inhibit host gene expression and antiviral response. However, the underlying mechanisms of the various Nsp1-mediated functions and their contributions to SARS-CoV-2 virulence remain unclear. Among the targets of Nsp1 is the mRNA (messenger ribonucleic acid) export receptor NXF1-NXT1, which mediates nuclear export of mRNAs from the nucleus to the cytoplasm. Based on Nsp1 crystal structure, we generated mutants on Nsp1 surfaces and identified an acidic N-terminal patch that is critical for interaction with NXF1-NXT1. Photoactivatable Nsp1 probe reveals the RNA Recognition Motif (RRM) domain of NXF1 as an Nsp1 N-terminal binding site. By mutating the Nsp1 N-terminal acidic patch, we identified a separation-of-function mutant of Nsp1 that retains its translation inhibitory function but substantially loses its interaction with NXF1 and reverts Nsp1-mediated mRNA export inhibition. We then generated a recombinant (r)SARS-CoV-2 mutant on the Nsp1 N-terminal acidic patch and found that this surface is key to promote NXF1 binding and inhibition of host mRNA nuclear export, viral replication, and pathogenicity in vivo. Thus, these findings provide a mechanistic understanding of Nsp1-mediated mRNA export inhibition and establish the importance of this pathway in the virulence of SARS-CoV-2.

Virus versus host: influenza A virus circumvents the immune responses.

Influenza A virus (IAV) is a highly contagious pathogen causing dreadful losses to humans and animals around the globe. As is known, immune escape is a strategy that benefits the proliferation of IAVs by antagonizing, blocking, and suppressing immune surveillance. The HA protein binds to the sialic acid (SA) receptor to enter the cytoplasm and initiate viral infection. The conserved components of the viral genome produced during replication, known as the pathogen-associated molecular patterns (PAMPs), are thought to be critical factors for the activation of effective innate immunity by triggering dependent signaling pathways after recognition by pattern recognition receptors (PRRs), followed by a cascade of adaptive immunity. Viral infection-induced immune responses establish an antiviral state in the host to effectively inhibit virus replication and enhance viral clearance. However, IAV has evolved multiple mechanisms that allow it to synthesize and transport viral components by "playing games" with the host. At its heart, this review will describe how host and viral factors interact to facilitate the viral evasion of host immune responses.

Matrine exhibits antiviral activities against PEDV by directly targeting Spike protein of the virus and inducing apoptosis via the MAPK signaling pathway

Porcine Epidemic Diarrhea Virus (PEDV) is a highly contagious virus that causes Porcine Epidemic Diarrhea (PED). This enteric disease results in high mortality rates in piglets, leading to significant financial losses in the pig industry. However, vaccines cannot provide sufficient protection against epidemic strains. Spike (S) protein exposed on the surface of virion mediates PEDV entry into cells. Our findings imply that matrine (MT), a naturally occurring alkaloid, inhibits PEDV infection targeting S protein of virions and biological process of cells. The GLY434 residue in the autodocking site of the S protein and MT conserved based on sequence comparison. This study provides a comprehensive analysis of viral attachment, entry, and virucidal effects to investigate how that MT inhibits virus replication. MT inhibits PEDV attachment and entry by targeting S protein. MT was added to cells before, during, or after infection, it exhibits anti-PEDV activities and viricidal effects. Network pharmacology focuses on addressing causal mechanisms rather than just treating symptoms. We identified the key genes and screened the cell apoptosis involved in the inhibition of MT on PEDV infection in network pharmacology. MT significantly promotes cell apoptosis in PEDV-infected cells to inhibit PEDV infection by activating the MAPK signaling pathway. Collectively, we provide the biological foundations for the development of single components of traditional Chinese medicine to inhibit PEDV infection and spread.

OASL suppresses infectious bursal disease virus replication by targeting VP2 for degrading through the autophagy pathway.

OASL (2´,5´-oligadenylate synthetase-like protein) exhibits broad-spectrum antiviral effects against single-stranded RNA viruses in mammals, potentially serving as a promising target for novel antiviral strategies. However, its role in inhibiting the replication of double-stranded RNA viruses (dsRNA viruses), such as infectious bursal disease virus (IBDV), in avian species remains unclear. Our findings indicated a unique and potent defense mechanism of OASL against dsRNA viruses. It has been previously shown in mammals that OASL inhibits virus replication through increasing interferon production. The groundbreaking aspect of our study is the finding that OASL has the ability to interact with IBDV viral protein VP2 and target it for degradation and thus exerts its antiviral effect. Our results reveal the interaction between avian natural antiviral immune response and IBDV infection. Our study not only enhances our understanding of bird defenses against viral infections but can also inform strategies for poultry disease management.

Structural basis of human mpox viral DNA replication inhibition by brincidofovir and cidofovir

Mpox virus has wildly spread over 108 non-endemic regions in the world since May 2022. DNA replication of mpox is performed by DNA polymerase machinery F8-A22-E4, which is known as a great drug target. Brincidofovir and cidofovir are reported to have broad-spectrum antiviral activity against poxviruses, including mpox virus in animal models. However, the molecular mechanism is not understood. Here we report cryogenic electron microscopy structures of mpox viral F8-A22-E4 in complex with a DNA duplex, or dCTP and the DNA duplex, or cidofovir diphosphate and the DNA duplex at resolution of 3.22, 2.98 and 2.79 Å, respectively. Our structural work and DNA replication inhibition assays reveal that cidofovir diphosphate is located at the dCTP binding position with a different conformation to compete with dCTP to incorporate into the DNA and inhibit DNA synthesis. Conformation of both F8-A22-E4 and DNA is changed from the pre-dNTP binding state to DNA synthesizing state after dCTP or cidofovir diphosphate is bound, suggesting a coupling mechanism. This work provides the structural basis of DNA synthesis inhibition by brincidofovir and cidofovir, providing a rational strategy for new therapeutical development for mpox virus and other pox viruses.

Dual N-linked glycosylation at residues 133 and 158 in the hemagglutinin are essential for the efficacy of H7N9 avian influenza virus like particle vaccine in chickens and mice

H7N9 subtype avian influenza virus (AIV) poses a great challenge to poultry industry. Virus-like particle (VLP) is a prospective alternative for the traditional egg-based influenza vaccines. N-linked glycosylation (NLG) regulates the efficacy of influenza vaccines, whereas the impact of NLG modifications on the efficacy of influenza VLP vaccines remains unclear. Here, H7N9 VLPs were assembled in insect cells through co-infection with the baculoviruses expressing the NLG-modified hemagglutinin (HA), neuraminidase and matrix proteins, and the VLP vaccines were assessed in chickens and mice. NLG modifications significantly enhanced hemagglutination-inhibition and virus neutralization antibody responses in mice, rather than in chickens, because different immunization strategies were used in these animal models. The presence of dual NLG at residues 133 and 158 significantly elevated HA-binding IgG titers in chickens and mice. The VLP vaccines conferred complete protection and significantly suppressed virus replication and lung pathology post challenge with H7N9 viruses in chickens and mice. VLP immunization activated T cell immunity-related cytokine response and inhibited inflammatory cytokine response in mouse lung. Of note, the presence of dual NLG at residues 133 and 158 optimized the capacity of the VLP vaccine to stimulate interleukin-4 expression, inhibit virus shedding or alleviate lung pathology in chickens or mice. Intriguingly, the VLP vaccine with NLG addition at residue 133 provided partial cross-protection against the H5Nx subtype AIVs in chickens and mice. In conclusion, dual NLG at residues 133 and 158 in HA can be potentially used to enhance the efficacy of H7N9 VLP vaccines in chickens and mammals.

Overview of Structural and Functional Insights of SLFN12 Associated With DifferentDiseases.

Schlafen12 is a member of the Schlafen gene family where Slfns have been linked to many functions such as anti-proliferation and cell differentiation, viral replication inhibition, migration of cancer cells and invasion prevention, and sensitivity to DNA-damaging medicines. Researchers are interested in studying the biochemical mechanisms that control thymocyte development to extract and describe gene expression and transcriptionally elevated by the process of positive selection that led to the discovery of this novel gene family. This review aims to give adequate knowledge about human SLFN12 by reviewing the most notable papers from five reliable databases regarding SLFN12 milestones and alterations in SLFN12 expression in various disease discoveries from 1997 to the present. In conclusion, SLFN12 seems to be linked with autoimmune diseases such as multiple sclerosis. Furthermore, SLFN12 levels could modify the effects of radiation and chemotherapy.

Inhibition of NADPH oxidase 2 enhances resistance to viral neuroinflammation by facilitating M1-polarization of macrophages at the extraneural tissues

BackgroundMacrophages play a pivotal role in the regulation of Japanese encephalitis (JE), a severe neuroinflammation in the central nervous system (CNS) following infection with JE virus (JEV). Macrophages are known for their heterogeneity, polarizing into M1 or M2 phenotypes in the context of various immunopathological diseases. A comprehensive understanding of macrophage polarization and its relevance to JE progression holds significant promise for advancing JE control and therapeutic strategies.MethodsTo elucidate the role of NADPH oxidase-derived reactive oxygen species (ROS) in JE progression, we assessed viral load, M1 macrophage accumulation, and cytokine production in WT and NADPH oxidase 2 (NOX2)-deficient mice using murine JE model. Additionally, we employed bone marrow (BM) cell-derived macrophages to delineate ROS-mediated regulation of macrophage polarization by ROS following JEV infection.ResultsNOX2-deficient mice exhibited increased resistance to JE progression rather than heightened susceptibility, driven by the regulation of macrophage polarization. These mice displayed reduced viral loads in peripheral lymphoid tissues and the CNS, along with diminished infiltration of inflammatory cells into the CNS, thereby resulting in attenuated neuroinflammation. Additionally, NOX2-deficient mice exhibited enhanced JEV-specific Th1 CD4 + and CD8 + T cell responses and increased accumulation of M1 macrophages producing IL-12p40 and iNOS in peripheral lymphoid and inflamed extraneural tissues. Mechanistic investigations revealed that NOX2-deficient macrophages displayed a more pronounced differentiation into M1 phenotypes in response to JEV infection, thereby leading to the suppression of viral replication. Importantly, the administration of H2O2 generated by NOX2 was shown to inhibit M1 macrophage polarization. Finally, oral administration of the ROS scavenger, butylated hydroxyanisole (BHA), bolstered resistance to JE progression and reduced viral loads in both extraneural tissues and the CNS, along with facilitated accumulation of M1 macrophages.ConclusionIn light of our results, it is suggested that ROS generated by NOX2 play a role in undermining the control of JEV replication within peripheral extraneural tissues, primarily by suppressing M1 macrophage polarization. Subsequently, this leads to an augmentation in the viral load invading the CNS, thereby facilitating JE progression. Hence, our findings ultimately underscore the significance of ROS-mediated macrophage polarization in the context of JE progression initiated JEV infection.

Suppressing FXR promotes antiviral effects of bile acids via enhancing the interferon transcription

Bile acids (BAs) are natural metabolites in mammals and have the potential to function as drugs against viral infection. However, the limited understanding of chenodeoxycholic acid (CDCA) receptors and downstream signaling, along with its lower suppression efficiency in inhibiting virus infection limits its clinical application. In this study, we demonstrate that farnesoid X receptor (FXR), the receptor of CDCA, negatively regulates interferon signaling, thereby contributing to the reduced effectiveness of CDCA against virus replication. FXR deficiency or pharmacological inhibition enhances interferon signaling activation to suppress virus infection. Mechanistically, FXR impairs the DNA binding and transcriptional abilities of activated interferon regulatory factor 3 (IRF3) through interaction. Reduced IRF3 transcriptional activity by FXR–IRF3 interaction significantly undermines the expression of Interferon Beta 1 (IFNB1) and the antiviral response of cells, especially upon the CDCA treatment. In FXR-deficient cells, or when combined with Z-guggulsterone (GUGG) treatment, CDCA exhibits a more potent ability to restrict virus infection. Thus, these findings suggest that FXR serves as a limiting factor for CDCA in inhibiting virus replication, which can be attributed to the “signaling-brake” roles of FXR in interferon signaling. Targeting FXR inhibition represents a promising pharmaceutical strategy for the clinical application of BAs metabolites as antiviral drugs.

Tat-dependent conditionally replicating adenoviruses expressing diphtheria toxin A for specifically killing HIV-1-infected cells

HIV-1 infection remains a public health problem with no cure. Although antiretroviral therapy (ART) is effective for suppressing HIV-1 replication, it requires lifelong drug administration due to a stable reservoir of latent proviruses and may cause serious side effect and drive the emergence of drug resistant HIV-1 variants. Gene therapy represents an alternative approach to overcome the limitations of conventional treatments against HIV-1 infection. In this study, we constructed and investigated the antiviral effects of an HIV-1 Tat-dependent conditionally replicating adenovirus, which selectively replicates and expresses the diphtheria toxin A chain (Tat-CRAds-DTA) in HIV-1 infected cells both in vitro and in vivo. We found that Tat-CRAds-DTA could specifically induce cell death and inhibit virus replication in HIV-1 infected cells mediated by adenovirus proliferation and DTA expression. A low titer of progeny Tat-CRAds-DTA was also detected in HIV-1 infected cells. In addition, Tat-CRAds-DTA showed no apparent cytotoxicity to HIV-1 negative cells and demonstrated significant therapeutic efficacy against HIV-1 infection in a humanized mouse model. Findings in this study highlight the potential of Tat-CRAds-DTA as a new gene therapy for the treatment of HIV-1 infection.

Targeted isolation of antiviral cinnamoylphloroglucinol-terpene adducts from Cleistocalyx operculatus by building blocks-based molecular networking approach

The building blocks-based molecular network (BBMN) strategy was applied to the phytochemical investigation of Cleistocalyx operculatus, leading to the targeted isolation of eighteen novel cinnamoylphloroglucinol-terpene adducts (CPTAs) with diverse skeleton types (cleistoperones A–R, 1–18). Their structures including absolute configurations were determined by extensive spectroscopic methods, quantum chemical calculations, and single-crystal X-ray crystallographic experiments. Cleistoperone A (1), consisting of a cinnamoylphloroglucinol motif and two linear monoterpene moieties, represents an unprecedented macrocyclic CPTA, whose densely functionalized tricyclo[15.3.1.03,8]heneicosane bridge ring skeleton contains an enolizable β,β′-triketone system and two different kinds of stereogenic elements (including five point and three planar chiralities). Cleistoperones B and C (2 and 3) are two new skeletal CPTAs with an unusual coupling pattern between the (nor)monoterpene moiety and the cinnamoyl chain of the cinnamoylphloroglucinol unit. Cleistoperone D (4) possesses an unprecedented cage-like 6/6/6/4/6-fused heteropentacyclic scaffold. The plausible biosynthetic pathways for 1–18 were also proposed. Notably, compounds 1, 4, 7, 8, and 18 exhibited significant antiviral activity against respiratory syncytial virus (RSV). The most potent one, cleistoperone A (1) with IC50 value of 1.71 ± 0.61 μmol/L, could effectively inhibit virus replication via affecting the Akt/mTOR/p70S6K signaling pathway.

Exploring the Antiviral Potential of Natural Compounds against Influenza: A Combined Computational and Experimental Approach.

The influenza A virus nonstructural protein 1 (NS1), which is crucial for viral replication and immune evasion, has been identified as a significant drug target with substantial potential to contribute to the fight against influenza. The emergence of drug-resistant influenza A virus strains highlights the urgent need for novel therapeutics. This study proposes a combined theoretical criterion for the virtual screening of molecular libraries to identify candidate NS1 inhibitors. By applying the criterion to the ZINC Natural Product database, followed by ligand-based virtual screening and molecular docking, we proposed the most promising candidate as a potential NS1 inhibitor. Subsequently, the selected natural compound was experimentally evaluated, revealing measurable virus replication inhibition activity in cell culture. This approach offers a promising avenue for developing novel anti-influenza agents targeting the NS1 protein.

Chemical shift assignment of dsRBD1 and dsRBD2 of Arabidopsis thaliana DRB3, an essential protein involved in RNAi-mediated antiviral defense.

As sessile organisms, plants need to counteract different biotic and abiotic stresses to survive. RNA interference provides natural immunity against various plant pathogens, especially against viral infections via inhibition of viral genome replication or translation. In plants, DRB3, a multi-domain protein containing two N-terminal dsRNA binding domains (dsRBD), plays a vital role in RNA-directed DNA methylation of the geminiviral genome. Additionally, DRB3 arrests the replication of the viral genome in the viral replication complex of RNA viruses through a mechanism that has yet to be fully deciphered. Therefore, as a first step towards exploring the structural details of DRB3, we present a nearly complete backbone and side chain assignment of the two N-terminal dsRBD domains.

Metabolomics captures the differential metabolites in the replication pathway of snakehead vesiculovirus regulated by glutamine.

Snakehead vesiculovirus (SHVV) is a negative-sense single-stranded RNA virus that infects snakehead fish. This virus leads to illness and mortality, causing significant economic losses in the snakehead aquaculture industry. The replication and spread of SHVV in cells, which requires glutamine as a nitrogen source, is accompanied by alterations in intracellular metabolites. However, the metabolic mechanisms underlying the inhibition of viral replication by glutamine deficiency are poorly understood. This study utilized liquid chromatography-mass spectrometry to measure the differential metabolites between the channel catfish Parasilurus asotus ovary cell line infected with SHVV under glutamine-containing and glutamine-deprived conditions. Results showed that the absence of glutamine regulated 4 distinct metabolic pathways and influenced 9 differential metabolites. The differential metabolites PS(16:0/16:0), 5,10-methylene-THF, and PS(18:0/18:1(9Z)) were involved in amino acid metabolism. In the nuclear metabolism functional pathway, differential metabolites of guanosine were observed. In the carbohydrate metabolism pathway, differential metabolites of UDP-d-galacturonate were detected. In the signal transduction pathway, differential metabolites of SM(d18:1/20:0), SM(d18:1/22:1(13Z)), SM(d18:1/24:1(15 Z)), and sphinganine were found. Among them, PS(18:0/18:1(9Z)), PS(16:0/16:0), and UDP-d-galacturonate were involved in the synthesis of phosphatidylserine and glycoprotein. The compound 5,10-methylene-THF provided raw materials for virus replication, and guanosine and sphingosine are related to virus virulence. The differential metabolites may collectively participate in the replication, packaging, and proliferation of SHVV under glutamine deficiency. This study provides new insights and potential metabolic targets for combating SHVV infection in aquaculture through metabolomics approaches.

In Vitro Anti-Rotaviral Activity of Bavachin Isolated from Psoralea corylifolia L. (Fabaceae).

Rotavirus is the main causative agent of viral gastroenteritis among young animals worldwide. Currently, no clinically approved or effective antiviral drugs are available to combat rotavirus infections. Herein, we evaluated the anti-rotaviral activities of extracts and bavachin isolated from Psoralea corylifolia L. (Fabaceae) (P. corylifolia) against the bovine rotavirus G8P[7] and porcine rotavirus G5P[7] in vitro. Two assay strategies were performed: (1) a virucidal assay to reduce viral infectivity by virus neutralization and (2) a post-treatment assay to assess viral replication suppression. The results from the virucidal assay showed that the extracts and bavachin did not exert anti-rotaviral activities. In the follow-up analysis after treatment, bavachin exhibited robust antiviral efficacy, with 50% effective concentration (EC50) values of 10.6 μM (selectivity index [SI] = 2.38) against bovine rotavirus G8P[7] and 13.0 μM (SI = 1.94) against porcine rotavirus G5P[7]. Bavachin strongly suppressed viral RNA synthesis in the early (6 h) and late stages (18 h) after rotaviral infection. These findings strongly suggest that bavachin may have hindered the virions by effectively inhibiting the early stages of the virus replication cycle after rotaviral infection. Furthermore, confocal imaging showed that bavachin suppressed viral protein synthesis, notably that of the rotaviral protein (VP6). These results suggest that bavachin has strong antiviral activity against rotaviruses, inhibits viral replication, and is a candidate natural therapeutic drug targeting rotaviral infection. The utilization of bavachin isolated from P. corylifolia may contribute to decreased mortality rates, lower medication expenses, and enhanced economic viability in domestic farms.