Contributions of neurotropic human herpesviruses herpes simplex virus 1 and human herpesvirus 6 to neurodegenerative disease pathology

Human herpesviruses （HVs） have developed ingenious mechanisms that enable them to traverse the defenses of the central nervous system （CNS）. The ability of HVs to enter a state of latency, a defining char- acteristic of this viral family, allows them to persist in the human host indefinitely. As such, HVs represent the most frequently detected pathogens in the brain. Under constant immune pressure, these infections are largely asymptomatic in healthy hosts. However, many neurotropic HVs have been directly connected with CNS pathology in the context of other stressors and genetic risk factors. In this review, we discuss the potential mechanisms by which neurotropic HVs contribute to neurodegenerative disease （NDD） patholo- gy by highlighting two prominent members of the HV family, herpes simplex virus 1 （HSV-1） and human herpesvirus 6 （HHV-6）. We （i） introduce the infectious pathways and replicative cycles of HSV-1 and HHV-6 and then （ii） review the clinical evidence supporting associations between these viruses and the NDDs Alzheimer＇s disease （AD） and multiple sclerosis （MS）, respectively. We then （iii） highlight and dis- cuss potential mechanisms by which these viruses exert negative effects on neurons and glia. Finally, we （iv） discuss how these viruses could interact with other disease-modifying factors to contribute to the initiation and/or progression of NDDs.

Current Status of Natural Products from Plants as Anti-herpes Simplex Virus 1 Agents

Nucleoside analogues have been the mainstay of clinical treatment of herpes simplex virus 1 (HSV-1) infections since their development. However, the emergence of drug resistant strains has underlined the urgency of the discovery of novel anti-HSV-1 drugs. Natural products, which provided many novel drug leads, are known to be an important source of anti-HSV-1 agents. Herein, we present an overview of natural products with anti-HSV-1 activities isolated from a variety of plants reported in recent years. Several different compounds, mainly belonging to the three groups of polysaccharides, polyphenols and terpenes, showed antiviral effects against HSV-1, indicating their potential to be promising anti-HSV-1 agents.

DNA vaccine expressing herpes simplex virus 1 glycoprotein C and D protects mice against herpes simplex keratitis

AIM： To investigate whether DNA vaccine encoding herpes simplex virus 1（HSV-1） glycoprotein C（g C） and glycoprotein D（g D） will achieve better protective effect against herpes simplex keratitis（HSK） than DNA vaccine encoding gD alone. METHODS： DNA vaccine expressing gD or gC combined g D（g D.g C） were constructed and carried by chitosan nanoparticle. The expression of fusion protein gD and gC were detected in DNA/nanoparticle transfected 293 T cells by Western-blot. For immunization, mice were inoculated with DNA/nanoparticle for 3 times with 2 wk interval, and two weeks after the final immunization, the specific immune responses and clinical degrees of primary HSK were evaluated. RESULTS： Fusion protein g D.g C could be expressed successfully in cultured 293 T cells. And, p RSC-g C.g DIL21 DNA/chitosan nanoparticle could effectively elicit strongest humoral and cellular immune response in primary HSK mice evidenced by higher levels of specific neutralizing antibody and s Ig A production, enhanced cytotoxicities of splenocytes and nature killer cells（NK）,when compared with those of gD alone or mocked vaccine immunized mice. As a result, gC-based vaccine immunized mice showed least HSK disease. CONCLUSION： gC-based DNA vaccine could effectively prevent the progress of primary HSK, suggesting that this DNA vaccine could be a promising vaccine for HSK treatment in the future.

Analysis of the Cellular Localization of Herpes Simplex Virus 1 Immediate-early Protein ICP22

Nuclear proteins often form punctiform structures, but the precise mechanism for this process is unknown. As a preliminary study, we investigated the aggregation of an HSV-1 immediate-early protein, infected-cell protein 22 （ICP22）, in the nucleus by observing the localization of ICP22-EGFP fusion protein Results showed that, in high-level expression conditions, ICP22-EGFP gradually concentrates in the nucleus, persists throughout the cell cycle without disaggregation even in the cell division phase, and is finally distributed to daughter cells. We subsequently constructed a mammalian cell expression system, which had tetracycline- dependent transcriptional regulators. Consequently, the location of ICP22-EGFP in the nucleus changed with distinct induction conditions. This suggests that the cellular location of ICP22 is also influenced by promoter regulation, in addition to its own structure. Our findings provide new clues for the investigation of transcriptional regulation of viral genes. In addition, the non-protease reporter system we constructed could be utilized to evaluate the role of intemal ribosome entry sites （IRES） on transcriptional regulation.

Interleukin 1βreceptor and synaptic dysfunction in recurrent brain infection with Herpes simplex virus type-1

Several experimental evidence suggests a link between brain Herpes simplex virus type-1 infection and the occurrence of Alzheimer’s disease.However,the molecular mechanisms underlying this association are not completely understood.Among the molecular mediators of synaptic and cognitive dysfunction occurring after Herpes simplex virus type-1 infection and reactivation in the brain neuroinflammatory cytokines seem to occupy a central role.Here,we specifically reviewed literature reports dealing with the impact of neuroinflammation on synaptic dysfunction observed after recurrent Herpes simplex virus type-1 reactivation in the brain,highlighting the role of interleukins and,in particular,interleukin 1βas a possible target against Herpes simplex virus type-1-induced neuronal dysfunctions.

Streptococcus pneumoniae and Herpes Simplex Virus-1 Central Nervous System Co-Infection

Co-infections of the central nervous system (CNS) caused by bacterial and viral pathogens are considered to be rare. Herpes simplex virus type-1 (HSV-1) reactivation following Streptococcus pneumoniae infection is well described but most cases are related to oral or cutaneous lesions or in respiratory samples. HSV-1 CNS reactivation after Streptococcus pneumoniae meningitis is a very rare event and may have significant morbidity and mortality. In this case report, we describe a 71-year-old female patient that presented with a history of abdominal pain and confusion/disorientation that had tonic-clonic seizures while in the Emergency Department. The diagnostic work-up confirmed CNS co-infection caused by Streptococcus pneumoniae and HSV-1. Of note, beyond age, the patient had no known risk factors for both entities and recovered fully after antibiotic and antiviral therapy. This case underlines that clinicians must be aware of CNS co-infection despite being a rare diagnosis. This should be suspected particularly in patients who present an unusual clinical course of CNS infection.

Attenuated phenotypes and analysis of a herpes simplex virus 1strain with partial deletion of the UL7, UL41 and LAT genes

We previously constructed a herpes simplex virus 1(HSV-1) UL7 mutant virus(M1) and showed that a partial deletion mutation of the UL7 gene led to a lower proliferative rate and an attenuated phenotype. Using the M1 mutant, we further modified the UL41 gene, which encodes another tegument protein, and the latency-associated transcript(LAT) gene. Observations of the resulting mutants with modified UL7 and UL41(M2) or UL7, UL41 and LAT(M3) genes indicated attenuated phenotypes, with lower proliferative ratios in various cells, non-lethal infections in mice and lower viral loads in nervous tissues compared with the wild-type strain. Furthermore, no LAT stable intron could be detected in the trigeminal ganglion of M3-infected animals. The results obtained with the three HSV-1 mutants indicate that the M3 mutant is an attenuated strain with low pathogenicity during both acute and latent infections. Together, the results support the use of the M3 mutant as a candidate for the development of an HSV-1 vaccine.

The Herpes Simplex Virus Type 1 Multiple Function Protein ICP27

The herpes simplex virus type 1 （HSV-1） infected-cell protein 27 （ICP27） is an essential, highly conserved protein involved in various steps of HSV-1 gene regulation as well as in the shut-off of host gene expression during infection. It functions primarily at the post-transcriptional level in inhibiting precursor mRNA splicing and in promoting nuclear export of viral transcripts. Recently, many novel functions performed by the HSV- 1 ICP27 protein were shown, including leptomycin B resistance, inhibition of the type I interferon signaling, regulation of the viral mRNA translation and determining the composition of HSV-1 virions

Feasibility of herpes simplex virus type 1 mutants labeled with radionuclides for tumor treatment

For over one hundred years, viruses have been recognized as capable of killing tumor cells. At present, people are still researching and constructing more suitable oncolytic viruses for treating different malignant tumors. Although extensive studies have demonstrated that herpes simplex virus type 1 (HSV-1) is the most potential oncolytic virus, therapies based on herpes simplex virus type 1 vectors still arouse bio-safety and risk management issues. Researchers have therefore introduced the new idea of treating cancer with HSV-1 mutants labeled with radionuclides, combining radionuclide and oncolytic virus therapies. This overview briefly summarizes the status and mechanisms by which oncolytic viruses kill tumor cells, discusses the application of HSV-1 and HSV-1 derived vectors for tumor therapy, and demonstrates the feasibility and prospect of HSV-1 mutants labeled with radionuclides for treating tumors.

A functional type I interferon pathway drives resistance to cornea herpes simplex virus type 1 infection by recruitment of leukocytes

Type I interferons are critical antiviral cytokines produced following herpes simplex virus type-1 （HSV-1） infection that act to inhibit viral spread. In the present study, we identify HSV-infected and adjacent uninfected corneal epithelial cells as the source of interferon-a. We also report mice deficient in the A1 chain of the type I IFN receptor （CDl18-/） are extremely sensitive to ocular infection with low doses （100 PFU） of HSV-1 as seen by significantly elevated viral titers in the cornea Compared to wild type （WT） controls. The enhanced susceptibil- ity correlated with a loss of CD4＋ and CD8＋ T cell recruitment and aberrant chemokine production in the cornea despite mounting an adaptive immune response in the draining mandibular lymph node of CDll8/ mice. Taken together, these results highlight the importance of IFN production in both the innate immune response as well as eliciting chemokine production required to facilitate adaptive immune cell trafficking.

The Herpes Simplex Virus Type 1 Infected Cell Protein 22

As one of the immediate-early(IE)proteins of herpes simplex virus type 1(HSV-1),ICP22 is a multifunctional viral regulator that localizes in the nucleus of infected cells.It is required in experimental animal systems and some nonhuman cell lines,but not in Vero or HEp-2 cells.ICP22 is extensively phosphorylated by viral and cellular kinases and nucleotidylylated by casein kinase Ⅱ.It has been shown to be required for efficient expression of early(E)genes and a subset of late(L)genes.ICP22,in conjunction with the UL13 kinase,mediates the phosphorylation of RNA polymerase Ⅱ.Both ICP22 and UL13 are required for the activation of cdc2,the degradation of cyclins A and B and the acquisition of a new cdc2 partner,the UL42 DNA polymerase processivity factor.The cdc2-UL42 complex mediates postranscriptional modification of topoisomerase Ⅱα in an ICP22-dependent manner to promote L gene expression.In addition,ICP22 interacts with cdk9 in a Us3 kinase dependent fashion to phosphorylate RNA polymerase Ⅱ.

Herpes simplex virus type 1 in peptic ulcer disease: An inverse association with Helicobacter pylori

AIM： To assess the frequency of herpes simplex virus type I in upper gastrointestinal tract ulcers and normal mucosa with the modern and better assays and also with a larger number of well characterized patients and controls and its relationship to Helicobacter pylori（H pylori）. METHODS： Biopsy specimens from 90 patients （34 with gastric ulcer of the prepyloric area and 56 with duodenal ulcer） were evaluated. Biopsies from 50 patients with endoscopically healthy mucosa were considered as the control group. The method used to identify herpes simplex virus-1 （HSV-1） was polymerase chain reaction. Hpylori was detected by the CLO-test and by histological method. RESULTS： Herpes simplex virus-1 was detected in 28 of 90 patients with peptic ulcer （31%） Ⅲ of 34 patients with gastric ulcer （32.4%） and 17 of 56 with duodenal ulcer （30.4%）1 exclusively close to the ulcerous lesion. All control group samples were negative for HSV-1. The likelihood of Hpylori negativity among peptic ulcer patients was significantly higher in HSV-1 positive cases than in HSV-1 negative cases （P = 0.009）. Gastric ulcer patients with HSV-1 positivity were strongly associated with an increased possibility of Helicobacter pylori negativity compared to duodenal ulcer patients （P = 0.010）. CONCLUSION： HSV-1 is frequent in upper gastrointestinal tract ulcers but not in normal gastric andduodenal mucosa. There is an inverse association between HSV-1 and Hpylori infection.

A Multiple Functional Protein:the Herpes Simplex Virus Type 1 Tegument Protein VP22

The herpes simplex virus type 1 （HSV-1） VP22, is one of the most abundant HSV-I tegument proteins with an average stoichiometry of 2 400 copies per virion and conserved among alphaherpesvirinae. Many functions are attributed to VP22, including nuclear localization, chromatin binding, microtubule binding, induction ofmicrotubule reorganization, intercellular transport, interaction with cellular proteins, such as template activating VP16, pU factor I （TAF-I） and nonmuscle myosin II A （NMIIA）, and viral proteins including pUS9 and pUL46, glycoprotein E （gE） and gD. Recently, many novel functions perform tegument protein ed by the HSV-1 VP22 protein have been shown, including promotion of protein synthesis at late times in infection, accumulation of a subset of viral mRNAs at early times in infection and possible transcriptional regulation function .

Herpes Simplex Virus Type 1 ICP27 Protein:Its Expression, Purification and Specific Antiserum Production

Herpes simplex virus type 1 (HSV-1) is the causative agent of cold sores and other more serious diseases. HSV-1 infected-cell protein 27 (ICP27) is an immediate-early regulatory phosphoprotein homologous to gene products identified in all classes of herpesviruses so far. To raise the antiserum to ICP27 for further characterization of its biological function, the ICP27 gene was cloned into the pET-28a (+) vector, then ICP27 protein was expressed in E. coli and purified by nickel-nitrilotriacetic acid (Ni 2+ -NTA) affinity resin column, finally the purified protein was used to raise antiserum. Western blot analysis demonstrated that the antiserum recognized the recombinant protein, and the antiserum was able to probe the ICP27 in HSV-1 infected cells with high specificity by immunofluorescence assay (IFA). Therefore, the specific antiserum will provide a valuable tool for further studies investigating ICP27's biological function during HSV-1 infection.

PNKP Knockdown by RNA Interference Inhibits Herpes Simplex Virus-1 Replication in Astrocytes

Herpes simplex virus-1 (HSV-1) is a major pathogen that causes various central nervous system (CNS) diseases,including herpes simplex encephalitis and meningitis.According to recent studies,PNKP significantly affects the proliferation of HSV-1 in astrocytes.Here,we used viral proliferation curves to confirm the significant inhibitory effects of PNKP on HSV-1 proliferation.PNKP downregulation was also confirmed by analyzing the transcription of viral genes.We found that PNKP downregulation affects the viral DNA copy number.This study preliminarily confirms that PNKP affects viral proliferation by affecting HSV-1 genome cyclization.These results also suggest that astrocytes play a specific role in preventing HSV-1 infection.

Preliminary study on Herpes simplex virus type 1 infection of human oral epithelial cell in vitro

Objective： To explore the functions and mechanisms of herpes simplex virus type I（HSV-1） while infecting human oral epithelial cells in vitro（being similar to the infection in vivo）. Methods：An abundance of HSV-1 strains amplified in Vero cells were used to infect human oral epithelial cells. The culture supernatant was collected to infect Vero cells again. Morphology of HSV-1 was identified by inverted microscope and transmission electron microscope. Nucleic acid of the virus was detected by PCR. Results：The infected human oral epithelial cells didn＇ t display an obvious cytopathic effect（CPE） under inverted microscope（while Vero cells which were infected by the culture supernatant showed typical（CPE）. The virus particles were not observed in the cytoplasm nor in nucleus of human oral epithelial cells, however under transmission electron microscope in the cytoplasm of Vero cells, the nucleic acid of HSV-1 could be detected in infected human oral epithelial cells, by PCR. Conclusion-HSV-1 can successfully infect human oral epithelial cells. This model may provide a useful approach for studying the pathogenesis of herpes virus-associated periodontal disease.

Effect of Gardenia extract ZG on the adsorption quantity of herpes simplex virus type 1 (HSV-1)

To observe the effect of Gardenia extract ZG on the adsorption quantity of herpes simplex virus type 1 （HSV-1） so as to explore the mechanism of its antiviral activity, fluorescein isothiocyanate （FITC） was used as the fluorescent probe to label viruses and heparin sodium was used as control. Meanwhile, the effect of Gardenia extract ZG on the adsorption quantity on the surface of Hep-2 cells was determined by flow cytometry. It was demonstrated that adsorption of HSV-1 on the surface of Hep-2 cells exhibited the character of saturation and specificity and heparin sodium could prevent attachment of viruses on these ceils. These results are in accord with those reported previously. It was also proved that the manner of drug-use prior to adsorption or simultaneous use of drug and adsorption was better than adsorption prior to drug-use, and the inhibition rates of the former and latter manner were 84.76% and 82.92% respectively. Three manners of drug-use with Gardenia extract ZG were all effective to reduce the adsorption quantity of viruses, especially the manner of simultaneous use of drug and adsorption with an adsorption inhibition rate of 68.46%. From the above observation, it is apparent that the mechanism of anti-viral activity of Gardenia extract ZG may be via several steps involved in the HSV-1 adsorption.

Anti-viral activity of Staphylococcus aureus lysates against herpes simplex virus type-Ⅰinfection:an in vitro and in vivo study

AIM:To investigate the effect of Staphylococcus aureus(S.aures)lysates(SALs)on herpes simplex virus type-Ⅰ(HSV1)infection in human corneal epithelial(HCE)cells and in a mouse model of HSV1 keratitis.METHODS:HCE,Vero,HeLa,and BV2 cells were infected with HSV1[HSV1f strain,HSV1f;HSV-1-H129 with green fluorescent protein(GFP)knock-in,HSV1g].Pre-or post-infection,SAL at various concentrations was added to the culture medium for 24 h.GFP fluorescence in HSV1g or plaque formation by HSV1f were examined.The effects of heat-treated SAL,precooled acetone-precipitated SAL,and SAL subjected to ultrafiltration(100 kDa)were evaluated.The effects of other bacterial components and lysates on HSV1 infection were also tested,including lipoteichoic acid(LTA),peptidoglycan(PGN),staphylococcal protein A(SPA),andα-hemolysin from S.aureus(α-toxin)as well as lysates from a wild-type S.aureus strain,S.epidermidis,and Escherichia coli(W-SAL,SEL,and ECL,respectively).In addition,SAL eye drops were applied topically to BALB/c mice with HSV1 keratitis,followed by in vivo observations.RESULTS:The cytopathic effect,plaque formation(HSV1f),and GFP expression(HSV1g)in infected cells were inhibited by SAL in a dose-dependent manner.The active component of SAL(≥100 kDa)was heat-sensitive and retained activity after acetone precipitation.In HSV1ginfected cells,treatment with LTA-sa,α-toxin,PGN-sa,or SPA did not inhibit GFP expression.SAL,W-SAL,and SEL(but not ECL)decreased GFP expression.In mice with HSV1 keratitis,SAL reduced corneal lesions by 71%.CONCLUSION:The results of this study demonstrate that SAL can be used to inhibit HSV1 infection,particularly keratitis.Further studies are needed to determine the active components and mechanism underlying the effects of SAL.

Oral and perioral herpes simplex virus infection type I in a fivemonth- old infant: A case report

BACKGROUND Herpes simplex virus(HSV)is a highly infectious pathogen that is easily transmitted via the bodily fluids of an infected individual.This virus usually affects individuals older than six months of age,and rarely causes lesions or symptoms in younger patients.CASE SUMMARY We present the case of a five-month-old healthy girl who presented with painful herpetic gingivostomatitis and perioral vesicles.We discuss the pathophysiology of primary HSV infection and the effect of maternal antibodies on the infant’s immune system.In addition,we explain the diagnosis,management,and prognosis of HSV infection in young infants.CONCLUSION This case highlights the importance of early diagnosis and management of HSV infections to decrease the risk of developing severe complications and death.

The Importance of Heparan Sulfate in Herpesvirus Infection

Herpes simplex virus type-1 (HSV-1) is one of many pathogens that use the cell surface glycosaminoglycan heparan sulfate as a receptor. Heparan sulfate is highly expressed on the surface and extracellular matrix of virtually all cell types making it an ideal receptor. Heparan sulfate interacts with HSV-1 envelope glycoproteins gB and gC during the initial attachment step during HSV-1 entry. In addition,a modified form of heparan sulfate,known as 3-O-sulfated heparan sulfate,interacts with HSV-1 gD to induce fusion between the viral envelope and host cell membrane. The 3-O-sulfation of heparan sulfate is a rare modification which occurs during the biosynthesis of heparan sulfate that is carried out by a family of enzymes known as 3-O-sulfotransferases. Due to its involvement in multiple steps of the infection process,heparan sulfate has been a prime target for the development of agents to inhibit HSV entry. Understanding how heparan sulfate functions during HSV-1 infection may not only be critical for inhibiting infection by this virus,but it may also be crucial in the fight against many other pathogens as well.