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Interferon α (IFNα) and interferon γ (IFNγ) play pivotal roles in mediating crucial biological functions, including antiviral activity and immune regulation. However, the efficacy of monomeric IFN is limited, and its administration relies solely on injection. To address this issue, we successfully expressed and purified a recombinant porcine IFNα and IFNγ fusion protein (rPoIFNα/γ). Furthermore, we developed a pH-triggered humic acid hydrogel delivery system that effectively protects rPoIFNα/γ from gastric acid degradation, enhancing its oral bioavailability. Neither the humic acid hydrogel nor rPoIFNα/γ exhibited cytotoxic effects on porcine kidney-15 (PK-15) cells in vitro. The replication of vesicular stomatitis virus and pseudorabies virus (PRV) was effectively inhibited by rPoIFNα/γ, resulting in an antiviral activity of approximately 10 4  U/mL. Scanning electron microscopy revealed that the humic acid hydrogel had a loose and porous honeycomb structure. The IFNα/γ@PAM gel hydrogel effectively adsorbed rPoIFNα/γ, as confirmed by Fourier transform infrared spectroscopy analysis, demonstrating a favourable IFN-loading capacity. In vitro experiments revealed that IFNα/γ@PAM gel swelled and released IFNα/γ rapidly at pH 7.4 but not at pH 1.2. The oral administration of IFNα/γ@PAM gel in mice enhanced the proliferation and differentiation of CD4 + and CD8 + cells. Additionally, mice infected with PRV and treated with IFNα/γ@PAM gel presented increased transcription levels of interferon-stimulated genes in the serum, reduced mortality rates, lower viral loads in various tissues, and decreased levels of organ damage. In conclusion, this study demonstrates that orally administered IFNα/γ@PAM gel has antiviral and immunomodulatory effects, highlighting its potential as a therapeutic agent against PRV infection., Competing Interests: Declarations. Ethics approval and consent to participate: The experiments involving mice were conducted in strict adherence to the principles of biosafety and bioethics, as well as the guidelines provided by the Animal Ethics Committee of Hebei Agricultural University, China (No. 2022145). Competing interests: The authors declare that they have no competing interests., (© 2024. The Author(s).)

Background: Pseudorabies virus (PRV), a member of the family Herpesviridae, is responsible for significant economic losses in the pig industry and has recently been associated with human viral encephalitis, leading to severe neurological symptoms post-recovery. Despite the widespread impact of PRV, there are currently no approved effective drugs for treating PRV-related diseases in humans or pigs. Therefore, the exploration and discovery of safe and effective drugs for the prevention and treatment of PRV infection is of paramount importance., Purpose: The objective of this study is to screen and identify natural compounds with antiviral activity against PRV., Methods: First, we used a strain of PRV with green fluorescent protein (PRV-GFP) to screen a natural product chemical library to identify potential antiviral drugs. Next, we assessed the antiviral abilities of salvianolic acid A (SAA) in vitro using virus titer assay, qPCR, and IFA. We investigated the mechanisms of SAA's antiviral activity through viral attachment, internalization, inactivation, and nuclease digestion assay. Finally, we evaluated the efficacy of SAA in inactivating PRV using mice as the experimental subjects., Results: This study screened 206 natural compounds for anti-PRV activity in vitro, resulting in the identification of seven potential antiviral agents. Notably, SAA emerged as a promising candidate with significant anti-PRV activity. The mechanism of action may be that SAA can directly inactivate the virus by disrupting viral envelope. In vivo experiments have shown that pre-incubation of SAA and PRV can effectively inhibit the infectivity and pathogenicity of PRV in mice., Conclusion: This study offers valuable insights into the antiviral properties of SAA, potentially informing strategies for controlling PRV epidemics and treating related diseases in both humans and animals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing fnancial interests or personal relationships that could have appeared to infuence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Background: The Pseudorabies Virus (PRV) leading to pseudorabies and causes huge economic losses in pig industry. The development of novel PRV variations has diminished the efficacy of traditional vaccinations, and there is yet no medication that can stop the spread of PRV infection. Therefore, PRV eradication is challenging. Oregano essential oil, the plant-based ingredient for medication feed have been shown to has strong anti-herpesvirus activity, but no anti-PRV function has been reported., Results: The current study assessed the anti-pseudorabies virus (PRV) activity of oregano essential oil and explored its mechanisms and most effective components against PRV. Our in vivo findings demonstrated that oregano essential oil could decrease the PRV load in tissues, mitigate tissue lesions, and enhance the survival rate of mice. The potential antiviral mechanism involves augmenting humoral and cellular immune responses in PRV-infected mice. To further investigate the most effective components of oregano essential oil against PRV, an in vitro study was conducted, revealing that oregano essential oil and its main constituents, carvacrol and thymol, all diminished PRV intracellular proliferation in vitro. Carvacrol exhibited the most potent anti-PRV effect, serving as the primary contributor to oregano essential oil's anti-PRV activity. The mechanisms underlying carvacrol's anti-PRV properties include the upregulation of cytokines TNF-α, IFN-β, IFN-γ, IL-12, and the inhibition of PRV-induced apoptosis in BHK-21 cells., Conclusions: Our study provides an effective drug for the prevention and control of PRV infection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Pseudorabies virus (PRV) is an important pathogen harming the global pig industry. Vaccines available for swine cannot protect against PRV completely. Furthermore, no antiviral drugs are available to treat PRV infections. Rehmmannia glutinosa polysaccharide (RGP) possesses several medicinal properties. However, its antiviral activity is not reported. In the present study, we found that RGP can inhibit PRV/XJ5 infection by western blotting, immunofluorescent assay (IFA), and TCID 50 assay quantitative polymerase chain reaction (qPCR). We revealed RGP can inhibit virus adsorption and invasion into PK-15 cells in a dose-dependent manner via western blotting, IFA, TCID 50 assay, and quantitative polymerase chain reaction (qPCR), and suppressed PRV/XJ5 replication through western blotting, and qPCR. Additionally, it also reduced PRV/XJ5-induced ROS, lipid oxidation, and improved SOD levels in PK-15 cells, which was observed by using corresponding test kits. To conclude, our findings suggest that RGP might be a novel therapeutic agent for preventing and controlling PRV infection and antioxidant agent., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024. Published by Elsevier B.V.)

Pseudorabies virus (PRV) is the causative agent of Aujeszky's disease, which is responsible for enormous economic losses to the global pig industry. Although vaccination has been used to prevent PRV infection, the effectiveness of vaccines has been greatly diminished with the emergence of PRV variants. Therefore, there is an urgent need to develop anti-PRV drugs. Polyethylenimine (PEI) is a cationic polymer and has a wide range of antibacterial and antiviral activities. This study found that a low dose of 1 µg/mL of the 25-kDa linear PEI had significantly specific anti-PRV activity, which became more intense with increasing concentrations. Mechanistic studies revealed that the viral adsorption stage was the major target of PEI without affecting viral entry, replication stages, and direct inactivation effects. Subsequently, we found that cationic polymers PEI and Polybrene interfered with the interaction between viral proteins and cell surface receptors through electrostatic interaction to exert the antiviral function. In conclusion, cationic polymers such as PEI can be a category of options for defense against PRV. Understanding the anti-PRV mechanism also deepens host-virus interactions and reveals new drug targets for anti-PRV.IMPORTANCEPolyethylenimine (PEI) is a cationic polymer that plays an essential role in the host immune response against microbial infections. However, the specific mechanisms of PEI in interfering with pseudorabies virus (PRV) infection remain unclear. Here, we found that 25-kDa linear PEI exerted mechanisms of antiviral activity and the target of its antiviral activity was mainly in the viral adsorption stage. Correspondingly, the study demonstrated that PEI interfered with the virus adsorption stage by electrostatic adsorption. In addition, we found that cationic polymers are a promising novel agent for controlling PRV, and its antiviral mechanism may provide a strategy for the development of antiviral drugs., Competing Interests: The authors declare no conflict of interest.

Importance: Pseudorabies virus (PRV) is a kind of alpha herpesvirus that infects a wide range of animals and even human beings. Therefore, it is important to explore the mechanisms behind PRV replication and pathogenesis. By conducting a tandem mass tag-based phosphoproteome, this study revealed the phosphorylated proteins and cellular response pathways involved in PRV infection. Findings from this study shed light on the relationship between the phosphorylated cellular proteins and PRV infection, as well as guiding the discovery of targets for the development of antiviral compounds against PRV., Competing Interests: The authors declare no conflict of interest.

With the urgent need for antiviral agents, antiviral materials with high biocompatibility and antiviral effects have attracted a lot of attention. In this study, gallic acid, a natural polyphenolic compound, was transformed into biocompatible graphene quantum dots (GAGQDs) which exhibit enhanced antiviral activity against pseudorabies virus (PRV). The as-prepared GAGQDs inhibit PRV proliferation with a 10 4 -fold reduction in viral titers. Investigation of the antiviral mechanism revealed that GAGQDs inhibit the adsorption, invasion and replication of PRV infection. Treatment with GAGQDs regulates the expression levels of interferon-related antiviral proteins, including mitochondrial antiviral-signaling protein (MAVS), signal transducer and activator of transcription 1 (STAT1) and 2',5'-oligoadenylate synthetase 1 (OAS1), suggesting that GAGQDs can stimulate innate antiviral immune responses, resulting in enhanced antiviral effects. More importantly, GAGQD treatments alleviate clinical symptoms and reduce mortality in PRV-infected mice. Our results reveal the enhanced therapeutic effects of GAGQDs against PRV infection in vitro and in vivo , suggesting the potential of GAGQDs as a promising novel antiviral agent.

Background: Pseudorabies virus (PRV) was thought to only infect animals. Recent studies have shown that it can also infect human., Case Presentation: We report a case of pseudorabies virus encephalitis and endophthalmitis, diagnosed 89 days after onset, confirmed with intraocular fluid metagenomic next generation sequencing (mNGS) after the result of two cerebrospinal fluid (CSF) mNGS tests were negative. Although treatment with intravenous acyclovir, foscarnet sodium, and methylprednisolone improved the symptoms of encephalitis, significant diagnostic delay resulted in permanent visual loss., Conclusions: This case suggests that pseudorabies virus (PRV) DNA in the intraocular fluid may have a higher positivity than that in the CSF. PRV may persist in the intraocular fluid for an extended period and may thus require extended antiviral therapy. Patients with severe encephalitis and PRV should be examined with the focus on pupil reactivity and light reflex. A fundus examination should be performed in patients with a central nervous system infection, specifically, those in a comatose state, to help reduce eye disability., (© 2023. The Author(s).)

Pseudorabies virus (PRV) has become a "new life-threatening zoonosis" since the human-originated PRV strain was first isolated in 2020. To identify novel anti-PRV agents, we screened a total of 107 β-carboline derivatives and found 20 compounds displaying antiviral activity against PRV. Among them, 14 compounds showed better antiviral activity than acyclovir. We found that compound 45 exhibited the strongest anti-PRV activity with an IC 50 value of less than 40 nM. Our in vivo studies showed that treatment with 45 significantly reduced the viral loads and protected mice challenged with PRV. To clarify the mode of action of 45, we conducted a time of addition assay, an adsorption assay, and an entry assay. Our results indicated that 45 neither had a virucidal effect nor affected viral adsorption while significantly inhibiting PRV entry. Using the FITC-dextran uptake assay, we determined that 45 inhibits macropinocytosis. The actin-dependent plasma membrane protrusion, which is important for macropinocytosis, was also suppressed by 45. Furthermore, the kinase DYRK1A (dual-specificity tyrosine phosphorylation-regulated kinase 1A) was predicted to be a potential target for 45. The binding of 45 to DYRK1A was confirmed by drug affinity responsive target stability and cellular thermal shift assay. Further analysis revealed that knockdown of DYRK1A by siRNA suppressed PRV macropinocytosis and the tumor necrosis factor alpha-TNF-induced formation of protrusions. These results suggested that 45 could restrain PRV macropinocytosis by targeting DYRK1A. Together, these findings reveal a unique mechanism through which β-carboline derivatives restrain PRV infection, pointing to their potential value in the development of anti-PRV agents., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Pseudorabies virus (PRV) is a pathogen that causes Aujeszky's disease (AD) in animals, leading to huge economic losses to swine farms. In order to discover anti-PRV compounds, we studied the extracts of the strain Streptomyces jiujiangensis NBERC-24992, which showed significant anti-PRV activity. Eight benzoheterocyclic secondary metabolites, including three new compounds ( 1 - 3 , virantmycins D-G) and five known compounds ( 4 - 8 , virantmycin, A-503451 D, A-503451 D acetylate, A-503451 A, and A-503451 B), were isolated from the broth of NBERC-24992. The structures of the new compounds were identified by using extensive spectroscopic data, including mass spectrometry (MS), nuclear magnetic resonance (NMR), and electronic circular dichroism (ECD). Compound 1 was found to be a novel heterocyclic compound with a tricyclic skeleton from natural product. All compounds were tested for antiviral activity, and 4 (virantmycin) showed an excellent effect against PRV and was better than ribavirin and acyclovir. Our study revealed that chlorine atom and tetrahydroquinoline skeleton were important active moiety for antiviral activity. Virantmycin could be a suitable leading compound for an antiviral drug against PRV.

Pseudorabies virus (PrV) is one of the most important herpesviruses which can cause severe diseases in many mammals and some avian species. In recent years, repeated outbreaks of pseudorabies worldwide indicated an urgent need for new control measures. The results described in this study demonstrated that an extract prepared from the rhizome of Kaempferia galanga L (Kge), which consisted of flavonoids (2.82%), saccharides (61.37%), phenols (1.22%) and saponins (3.10%), possessed a potent anti-PrV activity. In PK-15 cells, Kge treatment inhibited PrV-induced cell death by more than 90% at a dose of 200 μg/mL. The 50% inhibitory concentration (IC 50 ) was 55.85 μg/mL. In the PrV-infected mice treated with Kge, the survival rate was up to 60% at day 6 post-infection, while the infected mice without Kge treatment all died. The virus titers in the brains of the Kge-treated infected mice were significantly reduced. Kge treatment also alleviated the severity of the PrV-induced lesions in the heart, liver, spleen, lung and kidney. Kge exhibited immune-regulating activity through the regulation of cytokines (IFN-α, IFN-β, IL-4, IL-6 and TNF-α) in the serum of PrV-infected mice, suggesting that one possible mechanism of anti-PrV activity was through the regulation of immune function. These results suggested that Kge could be a promising drug candidate for treating PrV infections., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Pseudorabies virus (PRV) is one of the most important pathogens causing serious diseases and leads to huge economic losses in the global swine industry. With the continuous emergence of PRV variants and the increasing number of cases of human infection, there is an urgent need to develop antiviral drugs. In this study, we discover that Glycyrrhiza polysaccharide (GCP) has anti-PRV infection activity in vitro, and 600 μg/mL GCP can completely block viral infection. The addition of GCP simultaneously with or after PRV infection had a significant inhibitory effect on PRV. Addition of GCP at different times of the virus life cycle mainly led to the inhibition of the attachment and internalization of PRV but does not affect viral replication and release. Our findings suggest that GCP has potential as a drug against PRV infection.

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.

Pseudorabies virus (PRV) infection could cause severe histopathological damage via releasing multiple factors, including cytokines, peptides, etc. Here, peptidomic results showed that 129 peptides were identified in PRV-infected mouse lungs and were highly involved in the process of PRV infection. The role of one down-regulated biological peptide (designated as AGDP) during PRV infection was investigated. To verify the expression profiles of AGDP in response to PRV infection, the expression level of the precursor protein of AGDP mRNA was significantly decreased in PRV-infected mouse lungs and cells. The synthesized AGDP-treating cells were less susceptible to PRV challenges than the controls, as demonstrated by the decreased virus production and gE expression. AGDP not only inhibited the expression of TNF-α and IL-8 but also appeared to suppress the extracellular release of high-mobility group box 1 (HMGB1) by inhibiting the output of nuclear HMGB1 in cells. AGDP could also inhibit the degradation of IκBα and the phosphorylation levels of P65 after PRV infection. In total, our results revealed many meaningful peptides involved in PRV infection, thereby enhancing the current understanding of the host response to PRV infection, and how AGDP may serve as a promising candidate for developing novel anti-PRV drugs.

Porcine pseudorabies (PR) is an important infectious disease caused by pseudorabies virus (PRV), which poses a major threat to food safety and security. Vaccine immunization has become the main means to prevent and control the disease. However, since 2011, a new PRV variant has caused huge economic losses to the Chinese pig industry. Panax notoginseng polysaccharides have immunomodulatory activity and other functions, but the antiviral effect has not been reported. We studied the anti-PRV activity of Panax notoginseng polysaccharides in vitro. A less cytopathic effect was observed by increasing the concentration of Panax notoginseng polysaccharides. Western blot, TCID 50 , plaque assay, and IFA revealed that Panax notoginseng polysaccharides could significantly inhibit the infectivity of PRV XJ5 on PK15 cells. In addition, we also found that Panax notoginseng polysaccharides blocked the adsorption and replication of PRV to PK15 cells in a dose-dependent manner. These results show that Panax notoginseng polysaccharides play an antiviral effect mainly by inhibiting virus adsorption and replication in vitro. Therefore, Panax notoginseng polysaccharides may be a potential anti-PRV agent.

Pseudorabies virus (PRV) infection of swine can produce Aujeszky's disease, which causes neurological, respiratory, and reproductive symptoms, leading to significant economic losses in the swine industry. Although humans are not the natural hosts of PRV, cases of human encephalitis and endophthalmitis caused by PRV infection have been reported between animals and workers. Currently, a lack of specific treatments and the emergence of new PRV strains against which existing vaccines do not protect makes the search for effective antiviral drugs essential. As an alternative to traditional nucleoside analogues such as acyclovir (ACV), we studied the antiviral effect of valpromide (VPD), a compound derived from valproic acid, against PRV infection in the PK15 swine cell line and the neuroblastoma cell line Neuro-2a. First, the cytotoxicity of ACV and VPD in cells was compared, demonstrating that neither compound was cytotoxic at a specific concentration range after 24 h exposure. Furthermore, the lack of direct virucidal effect of VPD outside of an infected cell environment was demonstrated. Finally, VPD was shown to have an antiviral effect on the viral production of two strains of pseudorabies virus (wild type NIA-3 and recombinant PRV-XGF) at the concentrations ranging from 0.5 to 1.5 mM, suggesting that VPD could be a suitable alternative to nucleoside analogues as an antiherpetic drug against Aujeszky's disease.

Pseudorabies virus (PRV) accounts for a critical swine disease incurring economic losses worldwide. Several PRV vaccines are commercially available but these vaccines are effective against only certain prevalent PRV strains in China. To prevent PRV-induced latent infection and decrease the pathogenicity, novel anti-PRV drugs are required to prevent PRV infection. Natural products show exceptional structural diversity representing an important source for developing novel therapeutic agents. Quercetin is a flavonoid with anti-oxidant, anti-cancer, anti-bacterial and anti-viral activities. This study involved quercetin for studying the anti-PRV function in vitro and in vivo. Quercetin was found to significantly decrease the PRV virulent strain HNX at a half-maximal inhibitory concentration (IC 50 ) of 2.618 μM and selectivity index 229. This anti-PRV activity of quercetin was found to be dose-dependent. Furthermore, quercetin also inhibited a wide the infections by a spectrum of PRV strains like HNX, Ea, Bartha and Fa strain. These virucidal effects of quercetin suggest the interaction between these molecules and viral particles, and quercetin is responsible for inhibiting the adsorption of PRV infections. The silico assays suggesting that quercetin might interact with the gD-protein on the surface of the PRV important for viral infection. Additional, the quercetin plantar injection protected the mice from the lethal challenge, decreasing the PRV-infected mice's brain viral loads and mortality. These results provides a anti-PRV strategy and contribute to drug discovery and development., (Copyright © 2021. Published by Elsevier B.V.)

Pseudorabies virus (PRV) was isolated from some human cases recently and the infected patients manifested respiratory dysfunction and acute neurological symptoms. However, no effective drug or vaccine, preventing the progression of PRV infection, is available. Nectin-1 was the only reported receptor for PRV cell entry both swine and human origin, representing an excellent target to block PRV infection, and especially its transmission from pigs to humans. A PRV-gD specific mAbs (10B6) was isolated from hybridomas and its neutralizing activities in vitro and in vivo were determined. 10B6 exhibited effective neutralizing activities in vitro with IC 50  = 2.514 μg/ml and 4.297 μg/ml in the presence and absence of complement. And in vivo, 10B6 provided 100% protection against PRV lethal challenge with a dose of 15 mg/kg. Further, 10B6 could bind to a conserved epitope, 316 QPAEPFP 322 , locating in gD pro-fusion domain, and finally blocks the binding of PRV-gD to nectin-1. Moreover, 10B6 showed an effective inhibition on PRV cell-attachment in a cell type-independent manner and could also block the virus spreading among cells. 10B6 exhibited effectively neutralizing activities to Chinese PRV variant strain in vitro and in vivo by blocking gD binding to nectin-1, implied both prophylactic and therapeutic interventions against PRV infections., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Pseudorabies virus (PRV) is an enveloped double-stranded DNA virus that is the etiological agent of Aujeszky's disease in pigs. Vaccination is currently available to prevent PRV infection, but there is still an urgent need for new strategies to control this infectious disease. Histone deacetylases (HDACs) are epigenetic regulators that regulate the histone tail, chromatin conformation, protein-DNA interaction and even transcription. Viral transcription and protein activities are intimately linked to regulation by histone acetyltransferases and HDACs that remodel chromatin and regulate gene expression. We reported here that genetic and pharmacological inhibition of HDAC1 significantly influenced PRV replication. Moreover, we demonstrated that inhibition of HDAC1 induced a DNA damage response and antiviral innate immunity. Mechanistically, the HDAC1 inhibition-induced DNA damage response resulted in the release of double-strand DNA into the cytosol to activate cyclic GMP-AMP synthase and the downstream STING/TBK1/IRF3 innate immune signaling pathway. Our results demonstrate that an HDAC1 inhibitor may be used as a new strategy to prevent Aujeszky's disease in pigs., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Pseudorabies virus (PRV) is the causative pathogen of Aujeszky's disease in pigs. Although vaccination is currently applied to prevent the morbidity of PRV infection, new applications are urgently needed to control this infectious disease. Poly(ADP-ribose) polymerase 1 (PARP1) functions in DNA damage repair. We report here that pharmacological and genetic inhibition of PARP1 significantly influenced PRV replication. Moreover, we demonstrate that inhibition of PARP1 induced DNA damage response and antiviral innate immunity. Mechanistically, PARP1 inhibition-induced DNA damage response resulted in the release of double-stranded DNA (dsDNA) into the cytosol, where dsDNA interacted with cyclic GMP-AMP (cGAMP) synthase (cGAS). cGAS subsequently catalyzed cGAMP production to activate the STING/TBK1/IRF3 innate immune signaling pathway. Furthermore, challenge of mice with PARP1 inhibitor stimulated antiviral innate immunity and protected mice from PRV infection in vivo . Our results demonstrate that PARP1 inhibitors may be used as a new strategy to prevent Aujeszky's disease in pigs. IMPORTANCE Aujeszky's disease is a notifiable infectious disease of pigs and causes economic losses worldwide in the pig industry. The causative pathogen is PRV, which is a member of the subfamily Alphaherpesvirinae of the family Herpesviridae. PRV has a wide range of hosts, such as ruminants, carnivores, and rodents. More seriously, recent reports suggest that PRV can cause human endophthalmitis and encephalitis, which indicates that PRV may be a potential zoonotic pathogen. Although vaccination is currently the major strategy used to control the disease, new applications are also urgently needed for the pig industry and public health. We report here that inhibition of PARP1 induces DNA damage-induced antiviral innate immunity through the cGAS-STING signaling pathway. Therefore, PARP1 is a therapeutic target for PRV infection as well as alphaherpesvirus infection.

Background: Pseudorabies virus (PRV), a member of the Alphaherpesviruses, is one of the most important pathogens that harm the global pig industry. Accumulated evidence indicated that PRV could infect humans under certain circumstances, inducing severe clinical symptoms such as acute human encephalitis. Currently, there are no antiviral drugs to treat PRV infections, and vaccines available only for swine could not provide full protection. Thus, new control measures are urgently needed., Results: In the present study, kaempferol exhibited anti-PRV activity in mice through improving survival rate by 22.22 %, which was higher than acyclovir (Positive control) with the survival rate of 16.67 % at 6 days post infection (dpi); meanwhile, the survival rate was 0 % at 6 dpi in the infected-untreated group. Kaempferol could inhibit the virus replication in the brain, lung, kidney, heart and spleen, especially the viral gene copies were reduced by over 700-fold in the brain, which was further confirmed by immunohistochemical examination. The pathogenic changes induced by PRV infection in these organs were also alleviated. The transcription of the only immediate-early gene IE180 in the brain was significantly inhibited by kaempferol, leading to the decreased transcriptional levels of the early genes (EPO and TK). The expression of latency-associated transcript (LAT) was also inhibited in the brain, which suggested that kaempferol could inhibit PRV latency. Kaempferol-treatment could induce higher levels of IL-1β, IL-4, IL-6, TNF-α and IFN-γ in the serum at 3 dpi which were then declined to normal levels at 5 dpi., Conclusions: These results suggested that kaempferol was expected to be a new alternative control measure for PRV infection., (© 2021. The Author(s).)

Recently, pseudorabies virus (PRV) was isolated from human cases, and infected patients presented with respiratory dysfunction and acute neurological symptoms. However, there was no available effective drug to prevent the progression of PRV infection. In the present study, we screened a stably Drosophila S2 cell line which can secretory express a novel type I IFNs-interferon delta 8 (IFN-δ8) and the yield was about 10 mg/L. After purification, recombinant IFN-δ8 was demonstrated to be acid-stable, heat-stable, and nontoxic to PK-15 and 3D4/21 cells. Antiviral effects of IFN-δ8 against PRV were tested in vitro. Our results showed both pre- and post-treatment, recombinant PoIFN-δ8 exerted a significant protective effect against PRV infection in PK-15 and 3D4/21 cells. In addition, PoIFN-δ8 remarkably increased the expression of eight IFN-stimulated genes (ISGs), including ISG15, OAS1, PKR, MX1, CH25H, IFITM1, IFITM2 and IFITM3, to resist virus infection. These findings highlight the significance of IFN-δ8 that might serve as an antiviral agent for the prevention of PRV infection, and maybe expand the potential function of IFN antiviral drugs in the future., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Since 2011, highly pathogenic pseudorabies virus (PRV) variants that emerged on many farms in China have posed major economic burdens to the animal industry and have even recently caused several human cases of viral encephalitis. Currently, there are no approved effective drugs to treat PRV associated diseases in humans or pigs. Thus, it is important to develop a new effective drug for the treatment of PRV infection. To this end, we established a novel rapid method to screen drugs against PRV from 1818 kinds of small molecular drugs approved by the FDA. Using this method, we identified 21 kinds of them that can strongly suppress the proliferation of PRV. Mitoxantrone, puromycin dihydrochloride, mitoxantrone hydrochloride and adefovir dipivoxil effectively inhibited PRV in vitro. Of them, only adefovir dipivoxil could potently protect mice against lethal PRV infection. Our work identifies several kinds of potential therapeutics against PRV and may offer important guidance for controlling PRV epidemics and treating associated diseases in humans and animals., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Pseudorabies virus (PRV) is a prevalent and endemic swine pathogen that causes significant economic losses in the global swine industry. Due to the emergence of PRV mutant strains in recent years, vaccines can't completely prevent and control PRV infection. Therefore, research and development of new vaccines and drugs with inhibitory effects on PRV are of great significance in the prevention and treatment of PR. In this study, we firstly screened a library of 44 FDA-approved drugs and found that hydroquinone (HQ) displayed high anti-PRV activity by inhibiting PRV adsorption onto and internalization into cells. This study revealed that hydroquinone treatment stimulated genes associated with the PI3K-AKT signal pathway. HQ increased AKT mRNA production and activated AKT phosphorylation in N2a cells. This finding suggests that HQ significantly inhibits PRV replication by activating the phosphorylation of AKT. We also conducted in vivo experiments in mice. Hydroquinone significantly reduced the viral loads in mouse tissues and the mortality after PRV infection. The above results indicate that hydroquinone significantly inhibits the replication of PRV mutant strain ZJ01 in ICR mice and has an inhibitory effect on PRV. This study will contribute to the development of a novel prophylactic and therapeutic strategy against PRV infection., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Pseudorabies virus (PRV) primarily infects swine but can infect cattle, dogs, and cats. Several studies have reported that PRV can cross the specie barrier and induce human encephalitis, but a definitive diagnosis of human PRV encephalitis is debatable due to the lack of PRV DNA detection. Here, we report a case of human PRV encephalitis diagnosed by the next-generation sequencing (NGS) of PRV sequences in the cerebrospinal fluid (CSF) of a patient. A male pork vendor developed fever and seizures for 6 days. NGS results showed PRV sequences in his CSF and blood. Sanger sequencing showed that PRV DNA in the CSF and PRV antibodies in both the CSF and blood were positive. MRI results revealed multiple inflammatory lesions in the bilateral hemisphere. Based on the clinical and laboratory data, we diagnosed the patient with PRV encephalitis. This case suggests that PRV can infect humans, causing severe viral encephalitis. People at risk of PRV infection should improve their self-protection awareness.

Background: Porcine β-defensin 2 (PBD-2), produced by host cells, is an antimicrobial cysteine-rich cationic peptide with multi-functions. Previous studies have demonstrated that PBD-2 can kill various bacteria, regulate host immune responses and promote growth of piglets. However, the antiviral role of PBD-2 is rarely investigated. This study aimed to reveal the antiviral ability of PBD-2 against pseudorabies virus (PRV), the causative pathogen of Aujeszky's disease, in PK-15 cells and in a PBD-2 expressing transgenic (TG) mouse model., Methods: In this study, the cytotoxicity of PBD-2 on PK-15 cells was measured by CCK-8 assay. PK-15 cells were incubated with PRV pre-treated with different concentrations of PBD-2 and PRV titers in cell culture supernatants were determined by real-time quantitative PCR (RT-qPCR). TG mice and wild-type (WT) mice were intraperitoneally injected with PRV and the survival rate was recorded for 10 days. Meanwhile, tissue lesions in brain, spleen and liver of infected mice were observed and the viral loads of PRV in brain, liver and lung were analyzed by RT-qPCR., Results: PBD-2 at a maximum concentration of 80 μg/mL displayed no significant cytotoxicity on PK-15 cells. A threshold concentration of PBD-2 at 40 μg/mL was required to inhibit PRV proliferation in PK-15 cells. The survival rate in PBD-2 TG mice was 50% higher than that of WT mice. In addition, TG mice showed alleviated tissue lesions in brain, spleen and liver compared with their WT littermates after PRV challenge, while viral loads of PRV in brain, liver and lung of TG mice were significantly lower than that of WT mice., Conclusions: PBD-2 could inhibit PRV proliferation in PK-15 cells and protect mice from PRV infection, which confirmed the antiviral ability of PBD-2 both in vitro and in vivo. The application of PBD-2 in developing anti-viral drugs or disease-resistant animals can be further investigated.

Alphaherpesviruses that establish persistent infections rely partly on their ability to evade host antiviral responses, notably the type I interferon (IFN) response. However, the mechanisms employed by alphaherpesviruses to avoid this response are not well understood. Pseudorabies virus (PRV) is an economically important pathogen and a useful model system for studying alphaherpesvirus biology. To identify PRV proteins that antagonize type I IFN signaling, we performed a screen by using an IFN-stimulated response element reporter in the swine cell line CRL. Unexpectedly, we identified the dUTPase UL50 as a strong inhibitor. We confirmed that UL50 has the ability to inhibit type I IFN signaling by performing ectopic expression of UL50 in cells and deletion of UL50 in PRV. Mechanistically, UL50 impeded type I IFN-induced STAT1 phosphorylation, likely by accelerating lysosomal degradation of IFN receptor 1 (IFNAR1). In addition, this UL50 activity was independent of its dUTPase activity and required amino acids 225 to 253 in the C-terminal region. The UL50 encoded by herpes simplex virus 1 (HSV-1) also possessed similar activity. Moreover, UL50-deleted PRV was more susceptible to IFN than UL50-proficient PRV. Our results suggest that in addition to its dUTPase activity, the UL50 protein of alphaherpesviruses possesses the ability to suppress type I IFN signaling by promoting lysosomal degradation of IFNAR1, thereby contributing to immune evasion. This finding reveals UL50 as a potential antiviral target. IMPORTANCE Alphaherpesviruses can establish lifelong infections and cause many diseases in humans and animals. Pseudorabies virus (PRV) is a swine alphaherpesvirus that threatens pig production. Using PRV as a model, we found that this alphaherpesvirus could utilize its encoded dUTPase UL50 to induce IFNAR1 degradation and inhibit type I IFN signaling in an enzymatic activity-independent manner. Our finding reveals a mechanism employed by an alphaherpesvirus to evade the immune response and indicates that UL50 is an important viral protein in pathogenesis and is a potential target for antiviral drug development., (Copyright © 2017 American Society for Microbiology.)

Pseudorabies virus (PRV) is a pathogen of swine resulting in devastating disease and economic losses worldwide. Resveratrol (Res) exhibits inhibitory activity against a wide range of viruses. Despite these important advances, the molecular mechanism(s) by which Res exerts its broad biological effects have not yet been elucidated. In this paper, the antiviral activity of Res against PRV and its mechanism of action were investigated. The results showed that Res potently inhibited PRV replication in a dose-dependent manner, with a 50% inhibition concentration of 17.17 μM. The inhibition of virus multiplication in the presence of Res was not attributed to direct inactivation or inhibition of viral entry into the host cells but to the inhibition of viral multiplication in host cells. Further studies demonstrated that Res is a potent inhibitor of both NF-κB activation and NF-κB-dependent gene expression through its ability to inhibit IκB kinase activity, which is the key regulator in NF-κB activation. Thus, the inhibitory effect of Res on PRV-induced cell death and gene expression may be due to its ability to inhibit the degradation of IκB kinase. These results provided a new alternative control measure for PRV infection and new insights into the antiviral mechanism of Res.

African swine fever virus (ASFV) is one of the most dangerous viruses for pigs and is endemic in Africa but recently also spread into the Russian Federation and the Eastern border of the EU. So far there is no vaccine or antiviral drug available to curtail the infection. Thus, control strategies based on novel inhibitors are urgently needed. Another highly relevant virus infection in pigs is Aujeszky's disease caused by the alphaherpesvirus pseudorabies virus (PrV). This article reports the synthesis and biological evaluation of novel extracellular matrix-inspired entry inhibitors based on polyglycerol sulfate-functionalized graphene sheets. The developed 2D architectures bind enveloped viruses during the adhesion process and thereby exhibit strong inhibitory effects, which are equal or better than the common standards enrofloxacin and heparin as demonstrated for ASFV and PrV. Overall, the developed polyvalent 2D entry inhibitors are nontoxic and efficient nanoarchitectures, which interact with various types of enveloped viruses. Therefore they prevent viral adhesion to the host cell and especially target viruses that rely on a heparan sulfate-dependent cell entry mechanism., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Pseudorabies virus (PrV), a causative agent of Aujeszky's disease, is deadly to most mammals with the exception of higher primates and men. This disease causes serious economic loses among farm animals, especially pigs, yet many European countries are today claimed to be Aujeszky's disease free because of the discovery of an efficient vaccination for pigs. In reality, the virus is still present in wild boar. Current vaccines are neither suitable for dogs nor are there anti-PrV drugs approved for veterinary use. Therefore, the disease still represents a high threat, particularly for expensive hunting dogs that can come into close contact with infected boars. Here we report on the anti-PrV activities of a series of synthetic diaminopurine-based acyclic nucleoside phosphonate (DAP-ANP) analogues. Initially, all synthetic DAP-ANPs under investigation are shown to exhibit minimal cytotoxicity by MTT and XTT tests (1-100μM range). Thereafter in vitro infection models are established using PrV virus SuHV-1, optimized on PK-15 and RK-13 cell lines. Out of the six DAP-ANP analogues tested, analogue VI functionalized with a cyclopropyl group on the 6-amino position of the purine ring proves the most effective antiviral DAP-ANP analogue against PrV infection, aided by sufficient hydrophobic character to enhance bioavailability to its cellular target viral DNA-polymerase. Four other DAP-ANP analogues with functional groups introduced to the C2'position are shown ineffective against PrV infection, even with favourable hydrophobic properties. Cidofovir(®), a drug approved against various herpesvirus infections, is found to exert only low activity against PrV in these same in vitro models., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The experiment was conducted to evaluate the effects of dietary threonine (Thr) supplement on reproductive performance and immune function of the male mice challenged with pseudorabies virus (PRV). Kun-Ming male mice were assigned randomly to four groups with different Thr levels (0.70%, 0.88%, 1.10% and 1.30%). Half of the mice in each group were injected with PRV or phosphate-buffered saline (PBS) after 5 weeks' adaptation to diets. The second experiment examined the effects of dietary Thr level on copulation rate, pregnancy rate and average number per litter of PRV- or PBS-challenged male mice that copulated with adult female mice on the 9th day post PRV challenge. Sperm quality and testosterone of mice were decreased after PRV infection, but this effect was attenuated by increasing Thr levels. Copulation and conception rates were increased with increasing Thr levels (P = 0.14), but litter size was not affected (P > 0.05). In the PBS and PRV groups, mice fed higher levels of Thr had increased immunoglobulin (Ig)G, IgA and IgM concentrations. The PRV-specific antibody level, interleukin (IL)-1β and tumor necrosis factor (TNF)-α concentration in PRV groups enhanced with increasing Thr levels; however, there was no difference in PBS groups. Furthermore, higher toll-like receptor (TLR)2 and TLR9 expressions in testis were observed by PRV challenge compared with PBS groups, and higher Thr supplement attenuated PRV-challenged induced the upregulation effect of TLR2 and TLR9 mRNA expression in testis (P < 0.05). These data suggest that higher Thr consumption was recommended in order to counteract the deleterious effects of virus invasion, possibly through the downregulated expression of TLRs, and thus to improve immunity and reproduction performance of male mice challenged with PRV.

Carotenoids are effective antioxidants, which can quench singlet oxygen, suppress lipid peroxidation, and prevent oxidative damage. Both Pseudorabies virus (PRV) and human Herpes simplex virus (HSV) are DNA viruses, and their pathogenesis and immunobiology are similar. However, PRV does not infect humans. Therefore, PRV was used to infect murine macrophages (RAW264.7 cells), to mimic HSV-induced inflammation. Meanwhile, the influence of β-carotene on PRV-induced inflammation was also investigated. Results indicated that β-carotene inhibited (p<0.05) NO, IL-1β, IL-6, and MCP-1 production in PRV-infected RAW264.7 cells. β-Carotene also suppressed (p<0.05) NF-κB (p50 and p65), phosphorylation of extracellular-signal-related kinase (ERK), p38, and c-Jun N-terminal kinase (JNK) expression. It could be concluded that the anti-inflammatory effect of β-carotene is mainly through a suppression of cytokine expression in PRV-induced inflammation, which results from NF-κB inactivation. β-Carotene can be considered a potential anti-inflammatory agent for DNA-virus infection., (Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.)

Context: Pseudorabies herpesvirus (PrV) belongs to the Alphaherpesvirinae. Piglets infected with PrV die within a few days. Development of effective antiviral agents is one alternative or complementary method to prevent PrV infection. Houttuynia cordata Thunb. (Saururaceae), H. cordata, a traditional Chinese medicine, is often used to relieve lung abnormal symptoms, infectious disease, refractory hemoptysis and malignant pleural effusion in China., Objective: The present study aimed to investigate the effect of H. cordata injection on cell infection by PrV using Vero cells (a monkey kidney cell line) and swine testis cells (ST) as models., Materials and Methods: The infectivity of PrV was determined by plaque assays when H. cordata was applied to the virus, to the virus infected cells, and to the cells prior to infection. The genomic DNA copies post-drug treatment were confirmed by PCR and reverse transcription PCR. The cell apoptosis caused by the virus was analyzed., Results: H. cordata efficiently inhibited cell infection after incubating the drug with PrV. Nevertheless, H. cordata was more efficient in Vero cells than in ST cells in terms of its inhibitory effect. Low-dosage drug inhibited cell apoptosis induced by PrV; nevertheless, high-dosage drug alone resulted in cell apoptosis., Discussion and Conclusion: H. cordata has a direct inhibitory activity against PrV in vitro. H. cordata may be used as an anti-PrV agent or combined with other anti-PrV agents. PrV infection induces cell apoptosis and H. cordata inhibits cell infection. The optimal administration dosage of H. cordata should be taken into account in the future, because high-dosage H. cordata alone causes cell apoptosis.

Vitamin E supplement and pseudorabies virus (PRV) infection have a reciprocal role in influencing the maternal immune response, a key determinant of the success or failure of pregnancy. However, it remains unknown whether vitamin E supplement provides protection against PRV-induced failure of pregnancy. This study was therefore conducted to investigate the effect of dietary vitamin E level (0, 75, 375, 750 and 1,500 mg/kg) on the reproduction performance, immunity and expression of Toll-like receptors (TLRs) of PRV-challenged mice. The mortality and abortion rate of PRV-challenged mice decreased with the increase in vitamin E consumption. Overall, PBS-injected mice had a higher live embryo number and live litter size than PRV-challenged mice. Both live embryo number and live litter size of PRV-challenged mice increased with increasing vitamin E levels. Vitamin E supplement resulted in decreased concentration of serum IL-2 and IFN-γ, but increased concentration of serum IL-10. The concentration of serum IgG, IgA and IgM increased with increasing vitamin E levels. In the uterine and embryo mRNA abundance of TLR3, TLR7 and TLR9 was higher in PRV-challenged mice than that in PBS-injected mice fed on the same dosage of vitamin E. The mRNA abundance of embryonic TLR3, TLR7 and TLR9 in PRV-challenged mice decreased with increasing vitamin E levels. Collectively, vitamin E supplement may improve reproductive performance of PRV-challenged mice by attenuating PRV-induced negative effects on the cytokine profile, immunoglobulin synthesis and TLR expression.

Interferon (IFN) is crucial for initiating the innate immune response and for the generation of the adaptive response. IFN, in most species, comprises IFN-alpha (IFN-alpha), IFN-beta (IFN-beta) and IFN-gamma (IFN-gamma). In this study, we compared the capacity of porcine IFN-alpha, -beta and -gamma, or a combination of them, to protect IBRS-2 cells (porcine kidney cells) from infection with pseudorabies virus (PRV). The results demonstrated that porcine IFN-beta (PoIFN-beta) was the most efficient of the three IFNs in conferring resistance PRV infection; 100 U/mL PoIFN-beta inhibited PRV plaque formation 5.3-fold. Compared with PoIFN-beta, porcine IFN-gamma (PoIFN-gamma) was less capable of inhibiting PRV plaque formation (3.3-fold inhibition). Porcine IFN-alpha (PoIFN-alpha) had the least capability of the three PoIFNs, and inhibited PRV plaque formation only 1.26-fold. The inhibitory capacity increased to only 2.3-fold with a treatment of 12,800 U/mL PoIFN-alpha. A combination of PoIFN-gamma and PoIFN-alpha or PoIFN-beta inhibited PRV plaque formation 12.8-fold or 100-fold, respectively. Treatment of IBRS-2 cells with PoIFN-alpha/beta and PoIFN-gamma inhibited PRV replication 29- or 146-fold. Additionally, real-time PCR analyses of the PRV immediate early (IE) gene revealed that IE mRNA expression was profoundly decreased in cells stimulated with PoIFN-alpha/beta and PoIFN-gamma (23.8-133.0-fold) compared with vehicle-treated cells. All the findings indicate that PoIFN-gamma acts synergistically with other PoIFNs (PoIFN-alpha and -beta) to potently inhibit PRV replication in vitro.

Pseudorabies virus (PRV) is an alphaherpesvirus related to the human pathogens herpes simplex virus type 1 (HSV-1) and varicella-zoster virus. PRV is capable of infecting and killing a wide variety of mammals. How it avoids innate immune defenses in so many hosts is not understood. While the anti-interferon (IFN) strategies of HSV-1 have been studied, little is known about how PRV evades the IFN-mediated immune response. In this study, we determined if wild-type PRV infection can overcome the establishment of a beta interferon (IFN-beta)-induced antiviral state in primary rat fibroblasts. Using microarray technology, we found that the expression of a subset of genes normally induced by IFN-beta in these cells was not induced when the cells were simultaneously infected with a wild-type PRV strain. Expression of transcripts associated with major histocompatibility complex class I antigen presentation and NK cell activation was reduced, while transcripts associated with inflammation either were unaffected or were induced by viral infection. This suppression of IFN-stimulated gene expression occurred because IFN signal transduction, in particular the phosphorylation of STAT1, became less effective in PRV-infected cells. At least one virion-associated protein is involved in inhibition of STAT1 tyrosine phosphorylation. This ability to disarm the IFN-beta response offers an explanation for the uniform lethality of virulent PRV infection of nonnatural hosts.

The 2'-fluoropyrimidine nucleoside analogs 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodocytosine (FIAC). 1(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-methyluracil (FMAU), and 1(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodouracil (FIAU) showed higher in vitro activity against herpes simplex virus type 1 (HSV-1), than equine herpesvirus 1 (EHV-1) or pseudorabies virus (PRV). Comparison of the 50% plaque inhibitory doses for HSV-1 and its mutant MMdUr-20 in cell cultures with inhibition constants (Ki's) for the viral deoxythymidine kinases (dTKs) suggests that in the infected cell FMAU is phosphorylated by host enzymes. As compared to HSV-1, EHV-1 and PRV were more resistant to E-5-(2-bromovinyl-2'-deoxyuridine (BVdU) and to the 2'-fluoropyrimidine analogs, as are HSV-2 and the HSV-1 mutants MMdUr-20 and S1. Because the dTKs of the latter lack deoxythymidylate kinase (dTMPK) activity, there appears to be a correlation between resistance to these analogs and BVdU on the one hand, and lack of dTMPK activity on the other. We predict that EHV-1 and PRV dTKs will be shown to lack significant dTMPK activity.

Aujeszky's disease has been the subject of an eradication campaign in Denmark since 1980. A detailed knowledge of the virus strains present in the country was provided by restriction fragment analyses of older clinical isolates, and of isolates from all the virologically confirmed outbreaks since 1985. The introduction of foreign strains into southern border areas was demonstrated during the winters of 1984/85, 1986/87 and 1987/88. An epizootic during the winter of 1987/88 was shown to correlate with an unusual predominance of southerly winds. Both conventional and specific pathogen free herds became infected. A herd level case-control analysis of the outbreaks during the winter of 1987/88 revealed that there was a positive correlation between the risk of infection and the size of the herd. The observations support the hypothesis of airborne transmission of the disease.

Subunit pseudorabies vaccines that contained only purified glycoproteins of either of 2 strains of pseudorabies virus (PRV) were prepared and subsequently tested for safety and efficacy. The strains of virus used for vaccine production differed in at least 2 properties. One strain (Kojnok) was virulent for pigs and was believed to code for the entire complement of viral glycoproteins. The other (Kaplan) was a deletion mutant that was unable to code for structural viral glycoproteins gI and gp63. Purified glycoproteins were dispersed in an oil-in-water emulsion and were administered IM to pigs. Both vaccines were found to be safe and effective immunogens. Neither caused any local or general reactions, as verified by examination of the injection site (local safety) and by vaccination of pregnant sows in PRV-infected and noninfected herds. Sows vaccinated with the gI+ or gI- vaccine protected their pigs at levels of 93 and 92%, respectively, against a severe challenge exposure that killed 98% of pigs born from nonvaccinated sows. Vaccinated pigs were tested for active immunity by intranasal challenge exposure with the NIA 3 strain. Protection was quantitated by measuring the relative daily weight difference, expressed in percent per day, between vaccinated and control pigs during the first week after challenge exposure (delta G7); the estimated differences were 2.25 and 2.13% for gI+ and gI- vaccines, respectively. The absence of gI and gp63 did not affect the efficacy of this type of subunit glycoprotein vaccines.(ABSTRACT TRUNCATED AT 250 WORDS)

Compound BW759 (9-[2-hydroxy-1-(hydroxymethyl)ethoxymethyl]guanine) was shown to be about 230 times more active than acyclovir (9-[2-hydroxyethoxymethyl]guanine) (ACV) against Equid herpesvirus type 1 infection in Syrian hamsters and was more effective against Aujeszky's disease in mice. The therapeutic superiority of BW759 over ACV was greater than expected from quantitative inhibitory results in tissue culture with these viruses. When administered to hamsters at dose rates sufficient to prevent any Equid herpesvirus type 1-induced mortality (100 mg of ACV per kg per day; 3 mg of BW759 per kg per day), BW759 inhibited viral multiplication, as judged by histopathological observations, clinical chemistry, and liver virus concentrations, to a greater extent than ACV. Compound BW759 was particularly effective when administered via the oral route. The reasons for the superiority of BW759 over ACV remain to be elucidated.

Butylated hydroxytoluene (BHT) was evaluated for antiviral effectiveness on pseudorabies virus (PRV) in cell culture, mice, and swine. When relatively small amounts of BHT were mixed with PRV and incubated at 37 C for 30 or 60 minutes before inoculation into cell cultures, the cell cultures did not become infected with virus. The PRV was not infectious when the virus was treated with BHT and then inoculated intraperitoneally into mice, but was infectious when BHT and PRV were inoculated simultaneously or when BHT was inoculated either 30 or 60 minutes before PRV. Swine fed BHT-medicated feed for 10 days before they were intranasally exposed with virulent PRV did not have overt signs of pseudorabies, had a lower concentration of PRV in nasal mucus than did control swine, and had acceptable blood enzyme and cholesterol concentrations during the experiment. The BHT was detected in tissues of 2 swine after they were fed BHT-medicated feed for 10 days, and higher concentrations of BHT were detected in tissues of 3 swine given BHT feed for 29 days.

Two experimental porcine models of Aujeszky's disease (AD) were compared for assessing the efficacy of potential antiviral compounds. While signs were the same following intranasal inoculation and in-contact transmission of the causal herpesvirus, SHV-1 (Suid herpesvirus), the time-course of the disease was different. There was less variation in clinical signs between pigs following artificial infection, but the disease was more severe, making this a consistent but also more stringent test system. A nucleoside analogue, BW B759U (9-[1,3-dihydroxy-2-propoxy-methyl] guanine), was administered intramuscularly in divided twice daily doses at 50 mg kg-1 to three-week-old piglets in these two SHV-1 disease models. In artificially infected animals, in which treatment was begun 1.5 hours preinfection and continued for six days, there was a delay in the onset of clinical signs (4.8 compared with 3.2 days), a 1 log10 reduction in virus shedding, and a 1 to 2 log10 reduction in virus recovered from tissues, but all the treated piglets died from AD. In contrast, none of the BW B759U-treated piglets in the in-contact model system died during the eight-day medication period, although two piglets died subsequently. Mean serum concentrations of BW B759U two hours after intramuscular dosing were about 45 microM, at nine hours 15 to 20 microM and at 17 hours 3.5 microM. The in vitro IC50 of BW B759U against SHV-1 varies from 1.5 to 80 microM depending on the cell line in which the assay is carried out. There were no overt signs of BW B759U toxicity in the treated piglets.

The three 2'-fluoropyrimidine nucleosides 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodocytosine (FIAC), 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodouracil (FIAU), and 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-methyluracil (FMAU), showed high activity in RK13 monolayers against equine rhinopneumonitis virus, (EHV-1, IC50 range 0.02-0.18 microM), Aujeszky's disease virus (SHV-1, pseudorabies, IC50 range 0.25-7 microM) and infectious bovine rhinotracheitis virus (1BR, BHV-1, IC50 range 0.1-3 microM). The activity of these compounds was compared with 9-(1,3-dihydroxy-2-propoxymethyl)guanine (BW B759U, DHPG) in two laboratory animal disease models: EHV-1-induced hepatitis in hamsters and SHV-1-induced encephalitis in mice. All the compounds, provided from 3 to 5 h pre-infection for 5 days, were effective in preventing EHV-1 mortality (at 3-5 mg/kg per day) and in significantly reducing SHV-1 mortality (at 60 mg/kg per day). While FIAU had the greatest activity in vitro, FMAU tended to be more potent in vivo. The reasons for these differences between relative in vitro and in vivo activities are briefly discussed.

Disulfiram at concentrations between 0.1 and 0.3 mM inhibits the multiplication of Semliki Forest virus (SFV), fowl plague virus (FPV), Newcastle disease virus (NDV), vesicular stomatitis virus (VSV), and pseudorabies virus (PRV), when administered 1 hour before and during adsorption. There is, however, no inhibition of virus multiplication, when the drug is added after adsorption onto chick embryo cells. Disulfiram interferes neither with the receptors of the virus nor of erythrocytes, and it does not prevent virus adsorption. Possibly an early step in virus multiplication is affected by disculfiram. Infected cells once treated with the drug recover after some time of incubation in an ingibitor-free medium. The inhibitory state can be maintained, however, if relatively low doses of disulfiram are present in the culture medium also after adsorption. Disulfiram has no effect on macromolecular synthesis of the host cells. It has, however, a marked affect on membrane function. While virus multiplication is readily inhibited by disulfiram when chick embryo or BHK cells were investigated, virus multiplication in HeLa cells is almost resestant against the action of disulfiram.

Pseudorabies is a porcine herpesvirus of major importance in the swine industry. Isoprinosine is an immunomodulating drug that has been shown to be beneficial in treating herpesvirus infections. Twenty-four 7-week-old pigs were allotted within litters to 1 of 4 groups: control, isoprinosine (ISO), pseudorabies virus (PRV), or isoprinosine and pseudorabies virus (ISO-PRV). Isoprinosine was administered daily for 16 days to the ISO and ISO-PRV groups (75 mg/kg of body weight/day, PO). Immunity in pigs in the PRV and ISO-PRV groups was challenged with pseudorabies virus (10(5) TCID50 units) on day 4. Rectal temperatures and viral excretion were monitored daily; total and differential leukocyte counts, lymphocyte response to mitogens, and interleukin-2 production were monitored every 4 days. Pigs challenge-inoculated with pseudorabies virus became ill, with the ISO-PRV group most severely affected. Rectal temperatures were high (P less than 0.05) in virally challenged pigs on days 5 to 12 and 14 to 16; isoprinosine did not alter this effect. Pseudorabies virus-infected pigs had leukocytosis (P less than 0.05) on days 12 and 16, primarily caused by neutrophilia. Concanavalin A-stimulated lymphocyte proliferation was decreased (P less than 0.06) in both PRV and ISO-PRV groups on day 12, compared with control pigs, but only in the PRV group on day 16. Pokeweed mitogen-stimulated lymphocyte proliferation was decreased (P less than 0.02) in ISO-PRV pigs on day 8 of the experiment. Interleukin-2 concentrations, pooled over all sampling days, were decreased (P less than 0.03) in pseudorabies virus-infected pigs. Viral excretion was not altered by isoprinosine treatment. These data suggest that pseudorabies virus infection decreased lymphocyte proliferative responses and interleukin-2 production in pigs, and that isoprinosine did not mitigate these effects.

The effect of various concentrations of acyclovir on the mean plaque size of pseudorabies virus (SHV), infectious bovine rhinotracheitis virus (IBR virus) and pigeon herpesvirus (PHV) has been studied. Acyclovir significantly reduced the mean plaque size of SHV and PHV, whereas IBR virus was less affected and did only show a reduction of the mean plaque size at the highest concentration of acyclovir used (1000 microM). In vivo effect of acyclovir was tested using pigeons and budgerigars experimentally infected with PHV and rabbits experimentally infected with a very low dose of SHV. Intramuscular injections of acyclovir (100 mg/kg/day; three injections/day) did not prevent the appearance of clinical disease in infected pigeons nor did reduce the level of viral excretion. The same treatment applied, as for the pigeons, before infection protected most of the budgerigars as long as they were treated, but most of them died soon after the end of the treatment. Only one rabbit was protected by the treatment. SHV was recovered in the lung of only one of the treated animals, whereas it was isolated in the lungs of each control animal.

Pseudorabies virus (PRV) infection was established in mice by means of inoculating the ear flap. The infection was universally fatal once clinical signs appeared. Bromovinyldeoxyuridine (BVDU) was a potent inhibitor of PRV in vitro, but this drug failed to protect mice and produced only marginal reductions in virus titre and slight prolongation of survival. Acyclovir (ACV) and dihydroxypropoxymethylguanine (DHPG) were both less active than BVDU when tested against the virus in BHK cells, yet DHPG therapy was extremely effective in mice; it reduced virus titres markedly and resulted in the long-term survival of mice given a potentially lethal infection. When ACV and DHPG were tested in vitro using murine rather than hamster cells, these compounds, especially DHPG, were shown to be much more active against PRV.