Platycodon grandiflorus polysaccharides inhibit Pseudorabies virus replication via downregulating virus-induced autophagy

Lysimachia christinae polysaccharides dampen pseudorabies viral infection by downregulating adsorption and exert antioxidant activity

Pseudorabies virus (PRV) is an alpha herpes virus that causes pseudorabies. Pigs are the only natural hosts of the virus. This disease has caused considerable economic losses to the global pig industry. Since 2011, the effectiveness of vaccines has decreased greatly because of the emergence of various PRV varieties. Additionally, some people are infected with PRV. Therefore, the development of new anti-PRV agents is highly important. Lysimachia christinae is a traditional Chinese herbal medicine that has favorable effects on urine, detoxification, and swelling. In this study, the in vitro and in vivo anti-PRV activities of Lysimachia christinae polysaccharide (LCP) were investigated. Our results revealed that 200 μg/mL LCP significantly attenuated the infection of PK-15 B6 cells by PRV XJ5 and that 100 mg/kg LCP significantly reduced PRV XJ5 infection in mice. Mechanistic studies revealed that the main target of the anti-PRV effect of LCP was in the virus adsorption stage. In addition, our study revealed that LCP can reduce reactive oxygen species (ROS) and malondialdehyde (MDA) levels in PRV XJ5-infected PK-15 B6 cells and increase the activity of superoxide dismutase (SOD). These results showed that LCP can reduce the oxidative stress caused by PRV infection. In summary, LCP may be used as an antiviral drug to fight new PRV mutant strains.

Antiviral and Immune Enhancement Effect of Platycodon grandiflorus in Viral Diseases: A Potential Broad-Spectrum Antiviral Drug

BACKGROUND

Traditional Chinese medicine offers potential therapeutic options for viral infections. Platycodon grandiflorus (PG) is a perennial herb known for its efficacy in treating respiratory infections, including asthma, cough, and bronchitis, making it a key focus in antiviral drug research. The purpose of the study is to provide a basis for functional studies on PG and generate new insights for treating viral diseases.

METHODS

Research articles from 1990 to 2024 related to PG and viruses were obtained from databases, such as PubMed, Web of Science, and Science Direct, and systematically analysed.

RESULTS

PG demonstrates inhibitory effects on viruses such as severe acute respiratory syndrome coronavirus and porcine reproductive and respiratory syndrome virus by blocking various stages of viral proliferation or activating the host immune system. It also reduces inflammation through NF-κB, PI3K/AKT, MAPK, and other signalling pathways, enhancing T cell and macrophage function and increasing host immunity. PG exhibits diverse pharmacological effects with promising clinical applications for antiviral and immune modulation. Given its medicinal significance, PG holds substantial potential for further exploration and development.

CONCLUSION

PG, due to its antiviral, anti-inflammatory, and immune-boosting properties, can be used as an antiviral drug.

Evasion of the Antiviral Innate Immunity by PRV

Pseudorabies virus (PRV) establishes persistent latent infections by effectively evading the host's antiviral innate immune response. PRV has developed sophisticated strategies to bypass immune surveillance through coevolution with its host. Currently, no effective vaccine exists to prevent or treat infections caused by emerging PRV variants, and the interactions between PRV and the host's innate immune defenses remain incompletely understood. Nevertheless, ongoing research is uncovering insights that may lead to novel treatments and preventive approaches for herpesvirus-related diseases. This review summarizes recent advances in understanding how PRV disrupts key adaptors in immune signaling pathways to evade antiviral immunity. Additionally, we explored the intrinsic cellular defenses that play crucial roles in combating viral invasion. A deeper understanding of the immune evasion strategies of PRV could inform the development of new therapeutic targets and vaccines.

Insight into the Interaction Mechanism of Pseudorabies Virus Infection

The pseudorabies virus (PRV), also known as suid alphaherpesvirus 1 (SuAHV-1), has garnered significant attention due to its broad host range and the economic losses it incurs in the swine industry. This review aims to provide a comprehensive understanding of the intricate virus-host interactions during PRV infection, focusing on the evasion strategies of the virus against the host responses. We also summarize the mechanisms by which PRV manipulates the host cell machinery to facilitate its replication and spread, while simultaneously evading detection and clearance by the immune system. Furthermore, we discuss the latest advancements, such as metabolic, autophagic, and apoptotic pathways in studying these interactions, highlighting the role of various cellular factors and pathways in elucidating virus-host dynamics. By integrating these insights, the article aims to provide a comprehensive overview of the molecular mechanisms underlying PRV pathogenesis and host response, paving the way for the development of novel therapeutic strategies against this virus.

Identification of porcine PARP11 as a restricted factor for pseudorabies virus

Introduction

PRV infection in swine can cause devastating disease and pose a potential threat to humans. Advancing the interplay between PRV and host is essential to elucidate the pathogenic mechanism of PRV and identify novel anti-PRV targets.

Methods

PARP11-KO PK-15 cells were firstly constructed by CRISPR/Cas9 technology. Next, the effect of PARP11-KO on PRV infection was determined by RT-qPCR, TCID50 assay, RNA-seq, and western blot.

Results and discussion

In this study, we identified PARP11 as a host factor that can significantly affect PRV infection. Inhibition of PARP11 and knockout of PARP11 can significantly promoted PRV infection. Subsequently, we further found that PARP11 knockout upregulated the transcription of NXF1 and CRM1, resulting in enhanced transcription of viral genes. Furthermore, we also found that PARP11 knockout could activate the autophagy pathway and suppress the mTOR pathway during PRV infection. These findings could provide insight into the mechanism in which PARP11 participated during PRV infection and offer a potential target to develop anti-PRV therapies.

Anti-virus activity and mechanisms of natural polysaccharides from medicinal herbs

There has been a sudden increase in viral diseases, such as coronavirus disease 2019 (COVID-19), causing significant harm to human and animal well-being, as well as economic development. Medicinal herbs, with a history of thousands of years in clinical use, contain versatile polysaccharides as one of their primary compounds. This review offers an overview of the antiviral effects of polysaccharides from medicinal herbs on viruses in humans, poultry, swine and aquaculture in recent years. The mechanism of these antiviral polysaccharides, involved in hindering various stages of the viral life cycle thereby blocking virus infection, is summarized. The review also explores other underlying mechanisms of antiviral effects, such as enhancing the immune response, regulating inflammatory reactions, balancing gut flora, reducing oxidative stress, and suppressing apoptosis through various corresponding signaling pathways. The structure-function relationships discussed in this article also aid in understanding the antiviral mechanism of natural polysaccharides, indicating the need for more in-depth research and analysis. Natural polysaccharides from medicinal herbs have emerged as valuable resources in the fight against viral infections, exhibiting high effectiveness. This review emphasizes the promising role of polysaccharides from medicinal herbs as potential candidates for blocking viral infections in humans and animals.

Polysaccharides from Platycodon grandiflorum: A review of their extraction, structures, modifications, and bioactivities

Platycodon grandiflorum (P. grandiflorum) has long been used as a food and traditional herbal medicine. As a food, P. grandiflorum is often transformed into pickles for consumption, and as a traditional Chinese medicine, P. grandiflorum clears the lung, nourishes the pharynx, dispels phlegm, and discharges pus. Polysaccharides are among the main active components of P. grandiflorum. Recent literature has described the preparation, identification, and pharmacological activity of these polysaccharides. Studies have shown that these polysaccharides exhibit a variety of significant biological effects in vitro and in vivo, such as immune stimulation and antioxidant, anti-liver injury, anti-apoptosis and antitumour effects. However, there is no systematic summary of the related research articles on P. grandiflorum polysaccharide, which undoubtedly brings some difficulties to the future research. The purpose of this review is to comprehensively describe research progress on the extraction, purification, structural characterization, modification, and biological activity of P. grandiflorum polysaccharides. The shortcomings of recent research are summarized, further research on their biological activity is proposed to provide new reference value for the application of P. grandiflorum polysaccharides in drugs and health products in the future.

Cr(VI) induces ferroptosis in DF-1 cells by simultaneously perturbing iron homeostasis of ferritinophagy and mitophagy

Hexavalent chromium [Cr(VI)] is an environmental pollutant known for its strong oxidizing and carcinogenic effects. However, its potential to induce ferroptosis in poultry remains poorly understood. This study aims to investigate the induction of ferroptosis by Cr(VI) in DF-1 cells and elucidate the underlying mechanisms. DF-1 cells exposed to Cr(VI) showed increased lipid reactive oxygen species and changes in ferroptosis marker genes (decreased expression of GPX4 and increased expression of COX2). Notably, the addition of the ferroptosis-specific inhibitor ferrostatin-1 (Fer-1) can reverse this effect. During the cell death process, Cr(VI) induced ferritinophagy, disrupting iron homeostasis and releasing labile iron ions. We predicted by docking that these iron ions would bind to mitochondrial membrane proteins through virtual docking. This binding was validated through colocalization analysis. In addition, Cr(VI) caused mitophagy, which releases additional ferrous ions. Therefore, Cr(VI) can induce the simultaneous release of ferrous ions through these pathways, thereby exacerbating lipid peroxidation and ultimately triggering ferroptosis in DF-1 cells. This study demonstrates that Cr(VI) can induce ferroptosis in DF-1 cells by disrupting intracellular iron homeostasis and providing valuable insights into the toxic effects of Cr(VI) in poultry and potentially other organisms.

Effect of levan polysaccharide on chronological aging in the yeast Saccharomyces cerevisiae

Levan is a fructose-based biopolymer with diverse applications in the medicinal, pharmaceutical, and food industries. However, despite its extensive biological and pharmacological actions, including antioxidant, anti-inflammatory, and antidiabetic properties, research on its anti-aging potential is limited. This study explored levan's impact on the chronological lifespan (CLS) of yeast Saccharomyces cerevisiae for the first time. The results show that levan treatment significantly extended the CLS of wild-type (WT) yeast by preventing the accumulation of oxidative stress markers (reactive oxygen species, malondialdehyde, and protein carbonyl content) and ameliorating apoptotic features such as reduced mitochondrial membrane potential, loss of plasma membrane integrity, and externalization of phosphatidylserine. By day 40 of the CLS, a significant increase in yeast viability of 6.8 % (p < 0.01), 11.9 % (p < 0.01), and 20.8 % (p < 0.01) was observed at 0.25, 0.5, and 1 mg/mL of levan concentrations, respectively, compared to control (0 %). This study's results indicate that levan treatment substantially modulates the expression of genes involved in the TORC1/Sch9 pathway. Moreover, levan treatment significantly extended the CLS of yeast antioxidant-deficient mutant sod2Δ and antiapoptotic gene-deficient mutant pep4Δ. Levan also extended the CLS of signaling pathway gene-deficient mutants such as pkh2Δ, rim15Δ, atg1, and ras2Δ, while not affecting the CLS of tor1Δ and sch9Δ.

The surface morphology of Atractylodes macrocephala polysaccharide and its inhibitory effect on PCV2 replication

BACKGROUND

Porcine infection with Porcine circovirus type 2 (PCV2) causes immunosuppression, which is easy to cause concurrent or secondary infection, making the disease complicated and difficult to treat, and causing huge economic losses to the pig industry. Total polysaccharide from the rhizoma of Atractylodes macrocephala Koidz. (PAMK) is outstanding in enhancing non-specific immunity and cellular immunity, and effectively improving the body's disease resistance, indicating its potential role in antiviral immunotherapy.

RESULTS

PAMK had the characteristics of compact, polyporous and agglomerated morphology, but does not have triple helix conformation. PCV2 infection led to the increase in LC3-II, degradation of p62 and the increase of viral Cap protein expression and viral copy number. PAMK treatment significantly alleviated PCV2-induced autophagy and inhibited PCV2 replication. Moreover, PAMK treatment significantly attenuated the increase of PINK1 protein expression and the decrease of TOMM20 protein expression caused by PCV2 infection, alleviated Parkin recruitment from cytoplasm to mitochondria and intracellular reactive oxygen species accumulation, restored mitochondrial membrane charge, alleviated viral Cap protein expression.

CONCLUSION

PAMK alleviates PCV2-induced mitophagy to suppress PCV2 replication by inhibiting the Pink 1/Parkin pathway. These findings may provide new insights into the prevention and treatment of PCV2. © 2023 Society of Chemical Industry.

Platycodon grandiflorus polysaccharide inhibits the inflammatory response of 3D4/21 cells infected with PCV2

Porcine circovirus type 2 (PCV2) infection cause multi-systemic inflammation in pigs. Platycodon grandiflorus polysaccharide (PGPSt) has been reported to have the effects of immune regulation and disease resistance. Nevertheless, the role and mechanism of PGPSt in the inflammatory response of 3D4/21 cells induced by PCV2 infection remain unclear. The present study aims to investigate effects of PGPSt on inflammatory response and its possible underlying mechanisms in vitro models. Cells were treated with PCV2 for 36 h to construct a cell inflammation model. The 3D4/21 cell lines were pretreated with or without PGPSt, and the changes of inflammation-related markers and the signaling pathway were detected by CCK-8, ELISA, qPCR and Western blot. The results showed that PGPSt was non-toxic to cells and protected PCV2-infected cells from inflammatory damage. PGPSt could significantly inhibit the high acetylation of histone H3 (AcH3) and histone H4 (AcH4), down-regulate HAT and up-regulate HDAC activity, and reduce the expression of pro-inflammatory enzymes iNOS and COX-2 proteins levels. Then the levels of IL-1β, IL-6 and TNF-α were significantly inhibited, and the level of IL-10 was promoted. We also observed that PGPSt inhibited the phosphorylation of p65, p38 and Erk1/2, which subsequently inhibited nuclear translocation of NF-κB p65 to express pro-inflammatory factors. In conclusion, PGPSt can reduce the inflammatory response by regulating histone acetylation, reducing the release of inflammatory factors, reducing the expression of pro-inflammatory enzymes, and inhibiting the activation of NF-κB and MAPKs signaling pathways. This suggests that PGPSt had an anti-inflammatory effect on the inflammatory response caused by PCV2 infection, which provided theoretical data support for the research.

Preparation methods, structural characteristics, and biological activity of polysaccharides from Platycodon grandiflorus

Platycodon grandiflorus (P. grandiflorus), a traditional Chinese medicinal herb used for both medicine and food, has a long history of treating respiratory infections, bronchitis, pneumonia, and other lung-related diseases. The therapeutic effects of P. grandiflorus are attributed to its chemical components, including polysaccharides. Among these components, Platycodon grandiflorus polysaccharides (PGP) are recognized as one of the most important and abundant active ingredients, exhibiting various biological activities such as prebiotic, antioxidant, antiviral, anticancer, antiangiogenic, and immune regulatory properties. Incorporating the principles of traditional Chinese medicine, carrier concepts, and modern targeted drug delivery technologies, PGP can influence the target sites and therapeutic effects of other drugs while also serving as a drug carrier for targeted and precise treatments. Therefore, it is essential to provide a comprehensive review of the extraction, separation, purification, physicochemical properties, and biological activities of PGP. In the future, by integrating new concepts, technologies, and processes, further references and guidance can be provided for the comprehensive development of PGP. This will contribute to the advancement of P. grandiflorus in various fields such as pharmaceuticals, health products, and food.

Recent advances in Platycodon grandiflorum polysaccharides: Preparation techniques, structural features, and bioactivities

Platycodon grandiflorum, a globally recognized medicinal and edible plant, possesses significant nutritional value and pharmacological value. In traditional Chinese medicine, it has the effects of tonifying the spleen and replenishing the Qi, moistening the lung and relieving the cough, clearing the heat and detoxifying, and relieving the pain. Accumulating evidence has revealed that the polysaccharides from P. grandiflorum (PGPs) are one of the major and representative biologically active macromolecules and have diverse biological activities, such as immunomodulatory activity, anti-inflammatory activity, anti-tumor activity, regulation of the gut microbiota, anti-oxidant activity, anti-apoptosis activity, anti-angiogenesis activity, hypoglycemic activity, anti-microbial activity, and so on. Although the polysaccharides extracted from P. grandiflorum have been extensively studied for the extraction and purification methods, structural characteristics, and pharmacological activities, the knowledge of their structures and bioactivity relationship, toxicologic effects, and pharmacokinetic profile is limited. The main purpose of the present review is to provide comprehensively and systematically reorganized information on extraction and purification, structure characterizations, and biological functions as well as toxicities of PGPs to support their therapeutic potentials and sanitarian functions. New valuable insights for future research regarding PGPs were also proposed in the fields of therapeutic agents and functional foods.

Membrane fusion, potential threats, and natural antiviral drugs of pseudorabies virus

Pseudorabies virus (PrV) can infect several animals and causes severe economic losses in the swine industry. Recently, human encephalitis or endophthalmitis caused by PrV infection has been frequently reported in China. Thus, PrV can infect animals and is becoming a potential threat to human health. Although vaccines and drugs are the main strategies to prevent and treat PrV outbreaks, there is no specific drug, and the emergence of new PrV variants has reduced the effectiveness of classical vaccines. Therefore, it is challenging to eradicate PrV. In the present review, the membrane fusion process of PrV entering target cells, which is conducive to revealing new therapeutic and vaccine strategies for PrV, is presented and discussed. The current and potential PrV pathways of infection in humans are analyzed, and it is hypothesized that PrV may become a zoonotic agent. The efficacy of chemically synthesized drugs for treating PrV infections in animals and humans is unsatisfactory. In contrast, multiple extracts of traditional Chinese medicine (TCM) have shown anti-PRV activity, exerting its effects in different phases of the PrV life-cycle and suggesting that TCM compounds may have great potential against PrV. Overall, this review provides insights into developing effective anti-PrV drugs and emphasizes that human PrV infection should receive more attention.

Antiviral activity of dandelion aqueous extract against pseudorabies virus both in vitro and in vivo

Pseudorabies virus (PRV) is one of the most significant pathogens of swine. In recent years, the continual emergence of novel PRV variants has caused substantial economic losses in the global pig industry. PRV can infect humans leading to symptoms of acute encephalitis with implications for public health. Thus, new measures are urgently needed to prevent PRV infection. This study evaluated the anti-PRV capability of dandelion aqueous extract (DAE) in vitro and in vivo. DAE was found to inhibit the multiplication of the PRV TJ strain in PK15 cells in a concentration-dependent manner, with a 50% inhibitory concentration (IC₅₀) of 0.2559 mg/mL and a selectivity index (SI) of 14.4. DAE inhibited the adsorption and replication stages of the PRV life cycle in vitro, and the expression of IE180, EP0, UL29, UL44, and UL52 was inhibited in the presence of DAE. In vivo experiment results of mice show that a 0.5 g/kg dose of DAE injected intraperitoneally protected 28.6% of the mice from the lethal challenge; decreased the viral load in the liver, lung, brain, heart, and kidney of PRV-infected mice; and attenuated brain damage caused by PRV infection. Furthermore, DAE could also ameliorate viral infection through regulation of the levels of cytokines (IFN-γ, TNF-α, and IL-4) in PRV-infected mouse serum. These results demonstrated that DAE exhibited potent inhibitory capability against PRV infection in vitro and in vivo; DAE is therefore expected to be a candidate TCM herb for use against PRV infection.

Platycodon grandiflorus Polysaccharides Alleviate Cr(VI)-Induced Apoptosis in DF-1 Cells via ROS-Drp1 Signal Pathway

Hexavalent chromium (Cr(VI)) is a widespread heavy metal that has been identified as a human carcinogen, and acute or chronic exposure to Cr(VI) can cause organ damage. Platycodon grandiflorus polysaccharide (PGPS) is a constituent extracted from the Chinese herb Platycodon grandiflorus, which has various pharmacological effects. Therefore, the author investigated the role of PGPSt in Cr(VI)-induced apoptosis in chicken embryo fibroblast cell lines (DF-1 cells). Firstly, this study infected DF-1 cells using Cr(VI) to set up a model for cytotoxicity and then added PGPSt. Then, the intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and apoptosis rate were evaluated. The results showed that PGPSt could inhibit Cr(VI)-induced mitochondrial damage and increase the apoptosis rate. For further exploration of the mechanism of regulation of PGPSt, the ROS-Drp1 pathway was investigated. The antioxidant N-acetyl-L-cysteine (NAC) and mitochondrial division inhibitor 1(Mdivi-1) were added, respectively. The results showed that the NAC and Mdivi-1 restored abnormal mitochondrial fission and cell apoptosis. Thus, PGPSt can alleviate Cr(VI)-induced apoptosis of DF-1 cells through the ROS-Drp1 signaling pathway, which may suggest new research ideas for developing new drugs to alleviate Cr(VI) toxicity.

Effects of polymer carriers on the occurrence and development of autophagy in drug delivery

Autophagy is an evolutionarily conserved catabolic process that can degrade cytoplasmic materials and recycle energy to maintain metabolite homeostasis in cells. Autophagy is closely related to various physiological or pathological processes. Macromolecular materials are widely used in drug delivery systems and disease treatments due to their intrinsic effects, such as altered pharmacokinetics and biodistribution. Interaction of autophagic flux or the signal pathway with macromolecules may cause autophagy inhibition or autophagy cell death. This review covers autophagy regulation pathways and macromolecular materials (including functional micelles, biodegradable and pH-sensitive polymers, biomacromolecules, dendrimers, coordination polymers, and hybrid nanoparticles) mediated autophagy modulation.

Progress of Research into Novel Drugs and Potential Drug Targets against Porcine Pseudorabies Virus

Pseudorabies virus (PRV) is the causative agent of pseudorabies (PR), infecting most mammals and some birds. It has been prevalent around the world and caused huge economic losses to the swine industry since its discovery. At present, the prevention of PRV is mainly through vaccination; there are few specific antivirals against PRV, but it is possible to treat PRV infection effectively with drugs. In recent years, some drugs have been reported to treat PR; however, the variety of anti-pseudorabies drugs is limited, and the underlying mechanism of the antiviral effect of some drugs is unclear. Therefore, it is necessary to explore new drug targets for PRV and develop economic and efficient drug resources for prevention and control of PRV. This review will focus on the research progress in drugs and drug targets against PRV in recent years, and discuss the future research prospects of anti-PRV drugs.

The canonical Wnt/β-catenin signaling pathway facilitates pseudorabies virus proliferation and enhances virus-induced autophagy

Pseudorabies virus (PRV) is a swine herpesvirus with a broad host range that causes significant economic losses worldwide. The Wnt/β-catenin signaling pathway is reportedly involved in multiple viruses' proliferation. In this study, we demonstrated that PRV infection significantly activated the Wnt/β-catenin signaling and promoted the nuclear translocation of β-catenin. Applying specific chemical inhibitors (FH535 and iCRT14) caused a remarkable decrease in PRV titers in various cell lines. Knockdown of β-catenin by siRNA also reduced the proliferation of PRV. On the contrary, treatment with lithium chloride (LiCl), an inhibitor of GSK3β, stimulated the Wnt/β-catenin signaling pathway and enhanced the PRV proliferation. Similarly, overexpression of β-catenin promoted PRV proliferation and reversed the antiviral effect of FH535. Moreover, LiCl promoted PRV-induced autophagy, whereas FH535 and iCRT14 showed converse effects. These findings suggest that PRV infection stimulates the canonical Wnt/β-catenin signaling pathway, facilitating PRV proliferation and regulating virus-induced autophagy. These data also provide potential targets for developing antiviral agents against PRV.

Polysaccharides from Medicine and Food Homology Materials: A Review on Their Extraction, Purification, Structure, and Biological Activities

Medicine and food homology (MFH) materials are rich in polysaccharides, proteins, fats, vitamins, and other components. Hence, they have good medical and nutritional values. Polysaccharides are identified as one of the pivotal bioactive constituents of MFH materials. Accumulating evidence has revealed that MFH polysaccharides (MFHPs) have a variety of biological activities, such as antioxidant, immunomodulatory, anti-tumor, hepatoprotective, anti-aging, anti-inflammatory, and radioprotective activities. Consequently, the research progress and future prospects of MFHPs must be systematically reviewed to promote their better understanding. This paper reviewed the extraction and purification methods, structure, biological activities, and potential molecular mechanisms of MFHPs. This review may provide some valuable insights for further research regarding MFHPs.

A Tug of War: Pseudorabies Virus and Host Antiviral Innate Immunity

The non-specific innate immunity can initiate host antiviral innate immune responses within minutes to hours after the invasion of pathogenic microorganisms. Therefore, the natural immune response is the first line of defense for the host to resist the invaders, including viruses, bacteria, fungi. Host pattern recognition receptors (PRRs) in the infected cells or bystander cells recognize pathogen-associated molecular patterns (PAMPs) of invading pathogens and initiate a series of signal cascades, resulting in the expression of type I interferons (IFN-I) and inflammatory cytokines to antagonize the infection of microorganisms. In contrast, the invading pathogens take a variety of mechanisms to inhibit the induction of IFN-I production from avoiding being cleared. Pseudorabies virus (PRV) belongs to the family Herpesviridae, subfamily Alphaherpesvirinae, genus Varicellovirus. PRV is the causative agent of Aujeszky’s disease (AD, pseudorabies). Although the natural host of PRV is swine, it can infect a wide variety of mammals, such as cattle, sheep, cats, and dogs. The disease is usually fatal to these hosts. PRV mainly infects the peripheral nervous system (PNS) in swine. For other species, PRV mainly invades the PNS first and then progresses to the central nervous system (CNS), which leads to acute death of the host with serious clinical and neurological symptoms. In recent years, new PRV variant strains have appeared in some areas, and sporadic cases of PRV infection in humans have also been reported, suggesting that PRV is still an important emerging and re-emerging infectious disease. This review summarizes the strategies of PRV evading host innate immunity and new targets for inhibition of PRV replication, which will provide more information for the development of effective inactivated vaccines and drugs for PRV.

Polysaccharides from Platycodonis Radix ameliorated respiratory syncytial virus-induced epithelial cell apoptosis and inflammation through activation of miR-181a-mediated Hippo and SIRT1 pathways

Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis in young children, but there are few safe and effective treatments for this disease. Platycodonis Radix is widely used as an antitussive and expectorant drug for preventing various diseases in lower respiratory tract, in which the polysaccharides are one of the main bioactivity constituents. In this study, the protective effects of the P. Radix polysaccharides (PRP) against RSV-induced bronchiolitis in juvenile mice and RSV-induced apoptosis of epithelial HEp-2 cells were investigated. The results showed that PRP obviously decreased the levels of IL-1β, IL-4, IL-6, TNF-α, IFN-γ and TSLP in lung tissues, and reduced the number of inflammatory cells in bronchoalveolar lavage fluid (BALF) of RSV-infected mice. Furthermore, it reduced the apoptosis of RSV-infected HEp-2 cells and remarkably inhibited the mRNA expressions of RSV L gene, which indicated that PRP affected transcription and replication of RSV in host cells. Compared with that in RSV-infected group, miR-181a-5p in the PRP-treated group presented the highest relative abundance and its expression was violently reduced by approximately 30%. Mechanistically, PRP had the similar effects as miR-181a-5p antagomir on RSV-induced apoptosis and inflammation in HEp-2 cells via upregulating BCL2, MLL3 and SIRT1, which could be reversed by miR-181a-5p mimic. Therefore, it demonstrated that PRP not only protected against RSV-induced lung inflammation in mice but also inhibited apoptosis of RSV-infected HEp-2 cells via suppressing miR-181a-5p and transcriptionally activating Hippo and SIRT1 pathways.

Antiviral Activity of Plantago asiatica Polysaccharide against Pseudorabies Virus In Vitro

Pseudorabies (PR) is an acute infectious disease of various domestic animals and wild animals caused by pseudorabies virus (PRV). It is mainly characterized by fever, itching, encephalomyelitis, and respiratory and neurological disorders. Plantago asiatica polysaccharide (PLP), extracted from the whole plant of Plantago asiatica L., showed immunomodulatory and antioxidation effects, but the antiviral activity had not been reported. In this study, the inhibitory effect of PLP on PRV infection was studied. Our study first revealed that PLP could inhibit PRV infection in a dose-dependent manner. By adding PLP at different stages of the virus's life cycle, we revealed that PLP could reduce the attachment and penetration of PRV into PK15 cells. The inhibition of PRV attachment was better than inhibition of PRV penetration. However, PLP did not affect PRV replication and inactivation. In addition, PLP decreased the intracellular ROS levels in infected cells significantly, and ROS scavenger NAC decreased PRV infection. Therefore, our study provided preliminary data of anti-PRV activity of PLP, which was established to be a novel anti-PRV infection agent.

Meclizine Inhibits Pseudorabies Virus Replication by Interfering With Virus Entry and Release

Pseudorabies virus (PRV) is a pathogen that causes substantial economic losses to the swine industry. With the emergence and widespread of PRV variants since 2011 in China, current commercial vaccines cannot provide complete protection against PRV infection. Therefore, antiviral drugs may work as an alternative way to control and prevent PRV. In this study, the inhibitory effects and underlying molecular mechanisms of meclizine against PRV were studied. Meclizine displayed a significant inhibitory effect against PRV when it was added before, simultaneously with, or after virus infection. The inhibitory effect of meclizine occurred during viral entry and cell-to-cell spreading but not at viral attachment into PK-15 cells. Meclizine also inhibited viral particle release at the late stage of infection. The antiviral effect of meclizine was tested in mice, and the results showed that meclizine reduced the severity of clinical symptoms and the viral loads in tissues, and delayed the death, after PRV challenge. The above results indicated that meclizine had an inhibitory effect on PRV. Our findings will contribute to the development of potential therapeutic drugs against PRV infection.