Inhibition of hepatitis B virus via selective apoptosis modulation by Chinese patent medicine Liuweiwuling Tablet

BACKGROUND

Liuweiwuling Tablet (LWWL) is a Chinese patent medicine approved for the treatment of chronic inflammation caused by hepatitis B virus (HBV) infection. Previous studies have indicated an anti-HBV effect of LWWL, specifically in terms of antigen inhibition, but the underlying mechanism remains unclear.

AIM

To investigate the potential mechanism of action of LWWL against HBV.

METHODS

In vitro experiments utilized three HBV-replicating and three non-HBV-replicating cell lines. The in vivo experiment involved a hydrodynamic injection-mediated mouse model with HBV replication. Transcriptomics and metabolomics were used to investigate the underlying mechanisms of action of LWWL.

RESULTS

In HepG2.1403F cells, LWWL (0.8 mg/mL) exhibited inhibitory effects on HBV DNA, hepatitis B surface antigen and pregenomic RNA (pgRNA) at rates of 51.36%, 24.74% and 50.74%, respectively. The inhibition rates of LWWL (0.8 mg/mL) on pgRNA/covalently closed circular DNA in HepG2.1403F, HepG2.2.15 and HepG2.A64 cells were 47.78%, 39.51% and 46.74%, respectively. Integration of transcriptomics and metabolomics showed that the anti-HBV effect of LWWL was primarily linked to pathways related to apoptosis (PI3K-AKT, CASP8-CASP3 and P53 pathways). Apoptosis flow analysis revealed that the apoptosis rate in the LWWL-treated group was significantly higher than in the control group (CG) among HBV-replicating cell lines, including HepG2.2.15 (2.92% ± 1.01% vs 6.68% ± 2.04%, P < 0.05), HepG2.A64 (4.89% ± 1.28% vs 8.52% ± 0.50%, P < 0.05) and HepG2.1403F (3.76% ± 1.40% vs 7.57% ± 1.35%, P < 0.05) (CG vs LWWL-treated group). However, there were no significant differences in apoptosis rates between the non-HBV-replicating HepG2 cells (5.04% ± 0.74% vs 5.51% ± 1.57%, P > 0.05), L02 cells (5.49% ± 0.80% vs 5.48% ± 1.01%, P > 0.05) and LX2 cells (6.29% ± 1.54% vs 6.29% ± 0.88%, P > 0.05). TUNEL staining revealed a significantly higher apoptosis rate in the LWWL-treated group than in the CG in the HBV-replicating mouse model, while no noticeable difference in apoptosis rates between the two groups was observed in the non-HBV-replicating mouse model.

CONCLUSION

Preliminary results suggest that LWWL exerts a potent inhibitory effect on wild-type and drug-resistant HBV, potentially involving selective regulation of apoptosis. These findings offer novel insights into the anti-HBV activities of LWWL and present a novel mechanism for the development of anti-HBV medications.

Human antimicrobial peptide inactivation mechanism of enveloped viruses

HYPOTHESIS

Enveloped viruses are pivotal in causing various illnesses, including influenza and COVID-19. The antimicrobial peptide LL-37, a critical part of the human innate immune system, exhibits potential as an antiviral agent capable of thwarting these viral threats. Its mode of action involves versatile and non-specific interactions that culminate in dismantling the viral envelope, ultimately rendering the viruses inert. However, the exact mechanism of action is not yet understood.

EXPERIMENTS

Here, the mechanism of LL-37 triggered changes in the structure and function of an enveloped virus is investigated. The bacteriophage "Phi6" is used as a surrogate for pathogenic enveloped viruses. Small angle X-ray and neutron scattering combined with light scattering techniques demonstrate that LL-37 actively integrates into the virus's lipid envelope.

FINDINGS

LL-37 addition to Phi6 leads to curvature modification in the lipid bilayer, ultimately separating the envelope from the nucleocapsid. Additional biological assays confirm the loss of virus infectivity in the presence of LL-37, which coincides with the structural transformations. The results provide a fundamental understanding of the structure-activity relationship related to enveloped viruses. The knowledge of peptide-virus interactions can guide the design of future peptide-based antiviral drugs and therapies.

The role of Traditional Chinese medicine in anti-HBV: background, progress, and challenges

Chronic hepatitis B (CHB) remains a major world's most serious public health issues. Despite the remarkable effect of nucleos(t)ide analogues (NAs) in inhibiting hepatitis B virus (HBV) deoxyribonucleic acid (DNA) as the first-line drug, there are several limitations still, such as poor antigen inhibition, drug resistance, low-level viremia, restricting patients' functional cure. Due to the constraints of NAs, traditional medicines, such as traditional Chinese medicine (TCM), have become more prevalently used and researched in the clinical treatment of CHB as complementary alternative therapies. As a consequence, the review focuses on the background based on HBV's life cycle as well as the NAs' limitations, progress based on direct and indirect pathway of targeting HBV of TCM, and challenges of TCM. We found TCMs play an increasingly important role in anti-HBV. In a direct antiviral way, they regulate HBV infection, replication, assembly, and other aspects of the HBV life cycle. As for indirect way, TCMs can exert anti-HBV effects through targeting the host, including immune regulation, apoptosis, autophagy, oxidative stress, etc. Especially, TCMs have the advantages of strong antigenic inhibition compared to NAs. Specifically, we can combine the benefits of TCMs in strong HBV antigen inhibition with the benefits of NAs in targeted antiviral effects, in order to find a suitable combination of "TCM + NAs" to contribute to Chinese knowledge of the realisation of the "global elimination of HBV by 2030" goal of the World Health Organization.

The crude extract from the flowers of Trollius chinensis Bunge exerts anti-influenza virus effects through modulation of the TLR3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The flowers of Trollius chinensis Bunge (Ranunculaceae) is a traditional Chinese medicine used to treat various inflammatory diseases, including upper respiratory infections, chronic tonsillitis, and pharyngitis. Recently, there has been growing research on the antiviral role of the flowers of T. chinensis Bunge. However, little is known about its anti-influenza virus effects and the underlying mechanisms.

AIM OF THE STUDY

This study aims to evaluate the therapeutic effects of the crude extract from the flowers of T. chinensis Bunge (CEFTC) on mice infected with influenza virus. We further explored its mechanism by detecting the expression of vital proteins (TLR3, TBK1, TAK1, IKKα, IRF3, and IFN-β) related to TLR3 signaling pathway.

MATERIALS AND METHODS

Mice were infected with influenza A virus (H1N1) through the nasal cavity and were intragastrically administered CEFTC at the dose of 0.2 mg/g once daily. The therapeutic effects of CEFTC were evaluated by blood cell count, lung index, spleen index, alveolar lavage fluid testing, and HE staining. Network pharmacology analysis predicted the potential signaling pathway between the flowers of T. chinensis Bunge and pneumonia. The expression of TLR3, TBK1, TAK1, IKKα, IRF3, and IFN-β in lung tissues were examined by Western blot assay. In addition, the immunofluorescence assay was applied to assess the effect of CEFTC on the distribution of IRF3 and IFN-β between nuclei and cytoplasm.

RESULTS

Compared with the infected group, the lung index was markedly reduced, and the pathological damage of the lungs was also attenuated in the CEFTC treatment group. The network pharmacology analysis indicated that the NF-κB pathway was a potential signaling pathway in the flowers of T. chinensis Bunge for the treatment of pneumonia, TLR3, IRF3, and TBK1 were crucial targets associated with pneumonia. Western blot assay demonstrated that in the high-dose virus infected group, CEFTC reduced the expression of TLR3, TAK1, TBK1, and IRF3. Furthermore, CEFTC could increase the nuclear distribution of IRF3 in alveolar epithelial cells after virus infection.

CONCLUSIONS

These results suggested that different doses of influenza virus could cause varying infection symptoms in mice. Moreover, CEFTC could exert anti-influenza virus effects by regulating the expression of TLR3, IRF3, IFN-β, TAK1, and TBK1 in the TLR3 signaling pathway.

Studies in the antiviral molecular mechanisms of 25-hydroxycholesterol: Disturbing cholesterol homeostasis and post-translational modification of proteins

Efficient antiviral drug discovery has been a pressing issue of global public health concern since the outbreak of coronavirus disease 2019. In recent years, numerous in vitro and in vivo studies have shown that 25-hydroxycholesterol (25HC), a reactive oxysterol catalyzed by cholesterol-25-hydroxylase, exerts broad-spectrum antiviral activity with high efficiency and low toxicity. 25HC restricts viral internalization and disturbs the maturity of viral proteins using multiple mechanisms. First, 25HC reduces lipid rafts and cholesterol in the cytomembrane by inhibiting sterol-regulatory element binding proteins-2, stimulating liver X receptor, and activating Acyl-coenzyme A: cholesterol acyl-transferase. Second, 25HC impairs endosomal pathways by restricting the function of oxysterol-binding protein or Niemann-pick protein C1, causing the virus to fail to release nucleic acid. Third, 25HC disturbs the prenylation of viral proteins by suppressing the sterol-regulatory element binding protein pathway and glycosylation by increasing the sensitivity of glycans to endoglycosidase. This paper reviews previous studies on the antiviral activity of 25HC in order to fully understand its role in innate immunity and how it may contribute to the development of urgently needed broad-spectrum antiviral drugs.

Antiviral agent fTDP stimulates the SA signaling pathway and enhances tobacco defense against tobacco mosaic virus

TEER-decreasing protein (TDP) from Flammulina velutipes was antiviral resource against tobacco mosaic virus (TMV). However, the resistance mechanisms have not been clarified. In this study, the fTDP (fusion teer-decreasing protein), obtained by prokaryotic fusion expression system, exhibited obvious protective efficacy against TMV and significantly suppressed the reproduction of TMV in tobacco. Transcriptomics and proteomics analysis showed that fTDP may interact with a receptor, activate the mitogen-activated protein kinase (MAPK) pathway and NB-ARC and increase the content of reactive oxygen species (ROS) and salicylic acid (SA), which promoted the hypersensitive response (HR) and system acquired resistance (SAR). SAR caused increased expression of catalase (CAT), pathogenesis-related protein 1 (PR1), phenylalanine ammonia lyase (PAL) and other proteins involved in pathogen defense, such as chalcone-dihydroflavone isomerase (CHI) and cytochrome P450. In conclusion, SAR was induced by fTDP to protect tobacco from TMV infection and alleviate the symptoms caused by the virus. The study provided a theoretical basis for the application of the TDP protein, which may represent a potential biopesticide.

Molecular docking and dynamics studies of curcumin with COVID-19 proteins

Coronavirus disease 2019 (COVID-19) is caused by a Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2), which is a positive-strand RNA virus. The SARS-CoV-2 genome and its association to SAR-CoV-1 vary from ca. 66 to 96% depending on the type of betacoronavirideae family members. With several drugs, viz. chloroquine, hydroxychloroquine, ivermectin, artemisinin, remdesivir, azithromycin considered for clinical trials, there has been an inherent need to find distinctive antiviral mechanisms of these drugs. Curcumin, a natural bioactive molecule has been shown to have therapeutic potential for various diseases, and its effect on COVID-19 is also currently being explored. In this study, we show the binding potential of curcumin targeted to a variety of SARS-CoV-2 proteins, viz. spike glycoproteins (PDB ID: 6VYB), nucleocapsid phosphoprotein (PDB ID: 6VYO), spike protein-ACE2 (PDB ID: 6M17) along with nsp10 (PDB ID: 6W4H) and RNA dependent RNA polymerase (PDB ID: 6M71) structures. Furthermore, representative docking complexes were validated using molecular dynamics simulations and mechanistic studies at 100 ns was carried on nucleocapsid and nsp10 proteins with curcumin complexes which resulted in stable and efficient binding energies and correlated with that of docked binding energies of the complexes. Both the docking and simulation studies indicate that curcumin has the potential as an antiviral against COVID-19.

Antiviral activities and applications of ribosomally synthesized and post-translationally modified peptides (RiPPs)

The emergence and re-emergence of viral epidemics and the risks of antiviral drug resistance are a serious threat to global public health. New options to supplement or replace currently used drugs for antiviral therapy are urgently needed. The research in the field of ribosomally synthesized and post-translationally modified peptides (RiPPs) has been booming in the last few decades, in particular in view of their strong antimicrobial activities and high stability. The RiPPs with antiviral activity, especially those against enveloped viruses, are now also gaining more interest. RiPPs have a number of advantages over small molecule drugs in terms of specificity and affinity for targets, and over protein-based drugs in terms of cellular penetrability, stability and size. Moreover, the great engineering potential of RiPPs provides an efficient way to optimize them as potent antiviral drugs candidates. These intrinsic advantages underscore the good therapeutic prospects of RiPPs in viral treatment. With the aim to highlight the underrated antiviral potential of RiPPs and explore their development as antiviral drugs, we review the current literature describing the antiviral activities and mechanisms of action of RiPPs, discussing the ongoing efforts to improve their antiviral potential and demonstrate their suitability as antiviral therapeutics. We propose that antiviral RiPPs may overcome the limits of peptide-based antiviral therapy, providing an innovative option for the treatment of viral disease.

Insights into antiviral mechanisms of remdesivir, lopinavir/ritonavir and chloroquine/hydroxychloroquine affecting the new SARS-CoV-2

Coronavirus disease 2019 (COVID-19) is a kind of viral pneumonia with an unusual outbreak in Wuhan, China, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). There is currently no licensed antiviral treatment available to prevent human CoV infection. The widespread clinical use and existing knowledge on antiviral mechanisms of remdesivir, lopinavir/ritonavir and chloroquine/hydroxychloroquine in the treatment of previous epidemic diseases, namely, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), may be helpful in the combat with novel SARS-CoV-2 infection. Recent clinical evidence didn't confirm the beneficial role of lopinavir/ritonavir and chloroquine/hydroxychloroquine for COVID-19 patients and their use was reassessed. We provide an overview of the current evidence into the mechanisms of action of these available drugs which are repurposed for treatment of the new virus. Available data identifies remdesivir as an adenosine analogue that can target the RNA-dependent RNA polymerase and block viral RNA synthesis. It has been a promising antiviral drug against a wide array of RNA viruses. 3CLpro is a major CoV protease that cleaves the large replicase polyproteins during viral replication and can be targeted by the protease inhibitor lopinavir/ritonavir but the clinical effects are controversial. Chloroquine/Hydroxychloroquine could impair the replication of SARSCoV-2 by multiple mechanisms and their immunomodulatory properties could ameliorate clinical manifestations that are mediated by immune reactions of the host although its beneficial effects are under question and need to be proven at the clinical level. Existing in vitro and in vivo evidence delineate the molecular mechanisms of these drugs in CoV-infected cells. Numerous studies demonstrated the ability of remdesivir to inhibit SARS-CoV-2 replication but future research would be needed to understand the exact mode of action of lopinavir/ritonavir and chloroquine/hydroxychloroquine in SARS-CoV-2 infected cells and to use this knowledge in the treatment of the current COVID-19.

Plant-derived compounds: A potential source of drugs against Tobacco mosaic virus

Tobacco mosaic virus (TMV) is an important plant virus that led to significant losses in the crops worldwide. In this study, the antiviral activities of Ursolic Acid (UA) and 4-methoxycoumarin against TMV and their underlying mechanisms were initially investigated for the first time. The results demonstrated that the antiviral effects of UA and 4-methoxycoumarin were as effective as those of the commercial agent lentinan, in either the protective effect, inactivation effect or curative effect. In addition, both plant-derived compounds could induce the resistance responses of tobacco plants against TMV, showing increased antioxidant enzyme activities (SOD and POD) and H2O2 accumulation in tobacco leaves after treatment with UA or 4-methoxycoumarin, along with highly expressed regulatory and defence genes in the salicylic acid signaling pathway. Meanwhile, electrolyte leakage and malondialdehyde experiments indicated that these effects did not result in phytotoxicity or damage to the leaf plasma membrane of tobacco plants. Collectively, the results demonstrate that UA and 4-methoxycoumarin have potential as eco-friendly and safe strategies to control TMV in the future.

Interferon-inducible MX2 is a host restriction factor of hepatitis B virus replication

BACKGROUND & AIMS

Non-cytolytic cure of HBV-infected hepatocytes by cytokines, including type I interferons (IFNs), is of importance for resolving acute and chronic infection. However, as IFNs stimulate hundreds of genes, those most relevant for HBV suppression remain largely unknown. Amongst them are the large myxovirus resistance (Mx) GTPases. Human MX1 (or MxA) is active against many RNA viruses, while MX2 (or MxB) was recently found to restrict HIV-1, HCV, and herpesviruses. Herein, we investigated the anti-HBV activity of MX2.

METHODS

The potential anti-HBV activity of MX2 and functional variants were assessed in transfected and HBV-infected hepatoma cells and primary human hepatocytes, employing multiple assays to analyze the synthesis and decay of HBV nucleic acids. The specific roles of MX2 in IFN-α-driven inhibition of HBV transcription and replication were assessed by MX2-specific shRNA interference (RNAi).

RESULTS

Both MX2 alone and IFN-α substantially inhibited HBV replication, due to significant deceleration of the synthesis and slight acceleration of the turnover of viral RNA. RNAi knockdown of MX2 significantly reduced the inhibitory effects of IFN-α. Strikingly, MX2 inhibited HBV infection by reducing covalently closed circular DNA (cccDNA), most likely by indirectly impairing the conversion of relaxed circular DNA to cccDNA rather than by destabilizing existing cccDNA. Various mutations affecting the GTPase activity and oligomerization status reduced MX2's anti-HBV activity.

CONCLUSION

MX2 is an important IFN-α inducible effector that decreases HBV RNA levels but can also potently inhibit HBV infection by indirectly impairing cccDNA formation. MX2 likely has the potential for therapeutic applications aimed at curing HBV infection by eliminating cccDNA.

LAY SUMMARY

This study shows that the protein MX2, which is induced by interferon-α, has important anti-hepatitis B virus (HBV) effector functions. MX2 can reduce the amount of covalently closed circular DNA, which is the form of DNA that HBV uses to maintain viral persistence within hepatocytes. MX2 also reduces HBV RNA levels by downregulating synthesis of viral RNA. MX2 likely represents a novel intrinsic HBV inhibitor that could have therapeutic potential, as well as being useful for improving our understanding of the complex biology of HBV and the antiviral mechanisms of interferon-α.

Giant virus vs amoeba: fight for supremacy

Since the discovery of mimivirus, numerous giant viruses associated with free-living amoebae have been described. The genome of giant viruses can be more than 2.5 megabases, and virus particles can exceed the size of many bacteria. The unexpected characteristics of these viruses have made them intriguing research targets and, as a result, studies focusing on their interactions with their amoeba host have gained increased attention. Studies have shown that giant viruses can establish host-pathogen interactions, which have not been previously demonstrated, including the unprecedented interaction with a new group of small viruses, called virophages, that parasitize their viral factories. In this brief review, we present recent advances in virophage-giant virus-host interactions and highlight selected studies involving interactions between giant viruses and amoebae. These unprecedented interactions involve the giant viruses mimivirus, marseillevirus, tupanviruses and faustovirus, all of which modulate the amoeba environment, affecting both their replication and their spread to new hosts.

The Scorpion Venom Peptide Smp76 Inhibits Viral Infection by Regulating Type-I Interferon Response

Dengue virus (DENV) and Zika virus (ZIKV) have spread throughout many countries in the developing world and infect millions of people every year, causing severe harm to human health and the economy. Unfortunately, there are few effective vaccines and therapies available against these viruses. Therefore, the discovery of new antiviral agents is critical. Herein, a scorpion venom peptide (Smp76) characterized from Scorpio maurus palmatus was successfully expressed and purified in Escherichia coli BL21(DE3). The recombinant Smp76 (rSmp76) was found to effectively inhibit DENV and ZIKV infections in a dose-dependent manner in both cultured cell lines and primary mouse macrophages. Interestingly, rSmp76 did not inactivate the viral particles directly but suppressed the established viral infection, similar to the effect of interferon (IFN)-β. Mechanistically, rSmp76 was revealed to upregulate the expression of IFN-β by activating interferon regulatory transcription factor 3 (IRF3) phosphorylation, enhancing the type-I IFN response and inhibiting viral infection. This mechanism is significantly different from traditional virucidal antimicrobial peptides (AMPs). Overall, the scorpion venom peptide Smp76 is a potential new antiviral agent with a unique mechanism involving type-I IFN responses, demonstrating that natural AMPs can enhance immunity by functioning as immunomodulators.

Sialic acid involves in the interaction between ovomucin and hemagglutinin and influences the antiviral activity of ovomucin

Ovomucin (OVM) plays an important role in inhibiting infection of various pathogens. However, this bioactivity mechanism is not much known. Here, the role of sialic acid in OVM anti-virus activity has been studied by ELISA with lectin or ligand. Structural changes of OVM after removing sialic acid were analyzed by circular dichroism and fluorescence spectroscopy. OVM could be binding to the hemagglutinin (HA) of avian influenza viruses H₅N₁ and H₁N₁, this binding was specific and required the involvement of sialic acid. When sialic acid was removed, the binding was significantly reduced 71.5% and 64.35%, respectively. Therefore, sialic acid was proved as a recognition site which avian influenza virus bound to. Meanwhile, the endogenous fluorescence and surface hydrophobicity of OVM removing sialic acid were increased and the secondary structure tended to shift to random coil. This indicated that OVM molecules were in an unfolded state and spatial conformation disorder raising weakly. Remarkably, free sialic acid strongly promoted OVM binding to HA and thereby enhanced the interaction. It may contribute to the inhibition of host cell infection, agglutinate viruses. This study can be extended to the deepening of passive immunization field.

Determining the Virus Life-Cycle Stage Blocked by an Antiviral

Among the members of the Arenaviridae family, Junín virus and Lassa virus represent important human health threats generating annual outbreaks of severe human hemorrhagic fever (HF) in endemic areas of Argentina and Western Africa, respectively. Given the lack of a specific and safe chemotherapy, the search for effective antiviral compounds is a continuous demanding effort. During the last two decades, academic research studies originated important results identifying novel molecules to be considered for further in vivo characterization. This chapter summarizes experimental in vitro approaches used to determine the possible mechanism of action of these antiviral agents.

Overview on the antiviral activities and mechanisms of marine polysaccharides from seaweeds

Marine polysaccharides are attracting increasing attention in medical and pharmaceutical development because of their important biological properties. The seaweed polysaccharides have now become a rich resource of potential antiviral drugs due to their antiviral activities against various viruses. The structural diversity and complexity of marine polysaccharides and their derivatives contribute to their antiviral activities in different phases of many different viral infection processes. This review mainly introduces the different types of seaweed polysaccharides and their derivatives with potent antiviral activities. Moreover, the antiviral mechanisms and medical applications of certain marine polysaccharides from seaweeds are also demonstrated.