Human antibodies to herpes simplex virus type 1 glycoprotein C are neutralizing and target the heparan sulfate-binding domain

Cellular Chondroitin Sulfate and the Mucin-like Domain of Viral Glycoprotein C Promote Diffusion of Herpes Simplex Virus 1 While Heparan Sulfate Restricts Mobility

The diffusion of viruses at the cell membrane is essential to reach a suitable entry site and initiate subsequent internalization. Although many viruses take advantage of glycosaminoglycans (GAG) to bind to the cell surface, little is known about the dynamics of the virus–GAG interactions. Here, single-particle tracking of the initial interaction of individual herpes simplex virus 1 (HSV-1) virions reveals a heterogeneous diffusive behavior, regulated by cell-surface GAGs with two main diffusion types: confined and normal free. This study reports that different GAGs can have competing influences in mediating diffusion on the cells used here: chondroitin sulfate (CS) enhances free diffusion but hinders virus attachment to cell surfaces, while heparan sulfate (HS) promotes virus confinement and increases entry efficiency. In addition, the role that the viral mucin-like domains (MLD) of the HSV-1 glycoprotein C plays in facilitating the diffusion of the virus and accelerating virus penetration into cells is demonstrated. Together, our results shed new light on the mechanisms of GAG-regulated virus diffusion at the cell surface for optimal internalization. These findings may be extendable to other GAG-binding viruses.

Antiviral strategies targeting herpesviruses

Herpesviruses, known as large DNA viruses, have a wide host range. In addition to human beings, cattle, and horses, even carp can be hosts for herpesvirus infection. Herpesviruses are pathogens possessing elaborate mechanisms that regulate host cell components for its replication, assembly and generating mature virus particles that can infect humans and most animals, usually causing multiple and lifelong infections. In addition, several human diseases, such as genital or mouth herpes, mononucleosis, and Burkitt lymphoma, are usually associated with herpesvirus infection. Blocking the steps of viral infection, such as entry, replication and assembly, may be an effective way for many different herpes viruses and their related diseases. Therefore, we aim to describe antiviral agents that are able to prevent herpesvirus entry, replication and assembly in host cells. We summarize antiviral strategies, including certain small molecular drugs, RNA interference and CRISPR/Cas9 system-based antiviral approaches, which represent promising approaches.

Glycoprotein C of Herpes Simplex Virus 1 Shields Glycoprotein B from Antibody Neutralization

Viruses have evolved strategies to avoid neutralization by the host antibody response. Herpes simplex virus (HSV) glycoprotein C (gC) functions in viral entry and binds to complement component C3b, inhibiting complement-mediated immunity. We investigated whether gC protects HSV from antibody neutralization. HSV-1 that lacks gC was more sensitive to complement-independent neutralization by a panel of gB monoclonal antibodies than a wild-type gC rescuant virus. The presence of gC decreased neutralization by 2- to 16-fold. The gB in the native envelope of HSV-1 had reduced reactivity with antibodies in comparison to gB from the gC-null virus, suggesting that gC hampers the recognition of gB epitopes in the viral particle. The protein composition of the gC-null virus, including the surface glycoproteins essential for entry, was equivalent to that of the wild type, suggesting that gC is directly responsible for the reduced antibody recognition and neutralization. The neutralizing activity of antibodies to gD and gH antibodies was also increased in HSV lacking gC. Together, the data suggest that HSV-1 gC protects the viral envelope glycoproteins essential for entry, including gB, by shielding them from neutralization as a potential mechanism of immune evasion.IMPORTANCE HSV-1 causes lifelong infection in the human population and can be fatal in neonatal and immunocompromised individuals. There is no vaccine or cure, in part due to the ability of HSV to escape the host immune response by various mechanisms. The HSV particle contains at least 15 envelope proteins, four of which are required for entry and replication. This work suggests a novel role for gC in shielding the HSV entry glycoproteins. gC may function to help HSV escape neutralization by antibodies.

Oncolytic herpes simplex virus tumor targeting and neutralization escape by engineering viral envelope glycoproteins

Oncolytic herpes simplex viruses (oHSVs) have been approved for clinical usage and become more and more popular for tumor virotherapy. However, there are still many issues for the oHSVs used in clinics and clinical trials. The main issues are the limited anti-tumor effects, intratumor injection, and some side effects. To overcome such challenges, here we review the genetic engineering of the envelope glycoproteins for oHSVs to target tumors specifically, and at the same time we summarize the many neutralization antibodies against the envelope glycoproteins and align the neutralization epitopes with functional domains of the respective glycoproteins for future identification of new functions of the glycoproteins and future engineering of the epitopes to escape from host neutralization.

Varicella-Zoster Virus Glycoproteins: Entry, Replication, and Pathogenesis

Varicella-zoster virus (VZV), an alphaherpesvirus that causes chicken pox (varicella) and shingles (herpes zoster), is a medically important pathogen that causes considerable morbidity and, on occasion, mortality in immunocompromised patients. Herpes zoster can afflict the elderly with a debilitating condition, postherpetic neuralgia, triggering severe, untreatable pain for months or years. The lipid envelope of VZV, similar to all herpesviruses, contains numerous glycoproteins required for replication and pathogenesis.

PURPOSE OF REVIEW

To summarize the current knowledge about VZV glycoproteins and their roles in cell entry, replication and pathogenesis.

RECENT FINDINGS

The functions for some VZV glycoproteins are known, such as gB, gH and gL in membrane fusion, cell-cell fusion regulation, and receptor binding properties. However, the molecular mechanisms that trigger or mediate VZV glycoproteins remains poorly understood.

SUMMARY

VZV glycoproteins are central to successful replication but their modus operandi during replication and pathogenesis remain elusive requiring further mechanistic based studies.

Herpes Simplex Virus (HSV) Modulation of Staphylococcus aureus and Candida albicans Initiation of HeLa 299 Cell-Associated Biofilm

Although herpes simplex virus type-1 (HSV-1), and type-2 (HSV-2), Staphylococcus aureus and Candida albicans co-habit the oral and genital mucosa, their interaction is poorly understood. We determined the effect HSV has on bacterial and/or fungal adherence, the initial step in biofilm formation. HeLa229 cells were infected with HSV-1 (KOS) gL86 or HSV-2 (KOS) 333gJ⁻ at a multiplicity of infection (MOI) of 50 and 10. S. aureus (ATCC 25923) and/or C. albicans (yeast forms or germ tube forms) were co-incubated for 30 min (37 °C; 5 % CO₂; 5:1 organism: HeLa cell ratio; n = 16) with virus-infected HeLa cells or uninfected HeLa cell controls. Post-incubation, the monolayers were washed (3x; PBS), lysed (RIPA), and the lysate plated onto Fungisel and/or mannitol salts agar for standard colony count. The level of HeLa-associated S. aureus was significantly decreased (P < 0.05) for both HSV-1- and HSV-2-infected cells, as compared to virus-free HeLa cell controls (38 and 59 % of control, respectively). In contrast, HSV-1 and HSV-2 significantly (P < 0.05) enhanced HeLa cell association of C. albicans yeast forms and germ tube approximately two-fold, respectively. The effect of S. aureus on germ tube and yeast form adherence to HSV-1- and HSV-2-infected cells was specific for the Candida phenotype tested. Our study suggests that HSV, while antagonist towards S. aureus adherence enhances Candida adherence. Furthermore, the combination of the three pathogens results in S. aureus adherence that is either unaffected, or partially restored depending on both the herpes viral species and the fungal phenotype present.

Multiple Comparison Analysis of Two New Genomic Sequences of ILTV Strains from China with Other Strains from Different Geographic Regions

To date, twenty complete genome sequences of ILTV strains have been published in GenBank, including one strain from China, and nineteen strains from Australian and the United States. To investigate the genomic information on ILTVs from different geographic regions, two additional individual complete genome sequences of WG and K317 strains from China were determined. The genomes of WG and K317 strains were 153,505 and 153,639 bp in length, respectively. Alignments performed on the amino acid sequences of the twelve glycoproteins showed that 13 out of 116 mutational sites were present only among the Chinese strain WG and the Australian strains SA2 and A20. The phylogenetic tree analysis suggested that the WG strain established close relationships with the Australian strain SA2. The recombination events were detected and confirmed in different subregions of the WG strain with the sequences of SA2 and K317 strains as parental. In this study, two new complete genome sequences of Chinese ILTV strains were used in comparative analysis with other complete genome sequences of ILTV strains from China, the United States, and Australia. The analysis of genome comparison, phylogenetic trees, and recombination events showed close relationships among the Chinese strain WG and the Australian strains SA2. The information of the two new complete genome sequences from China will help to facilitate the analysis of phylogenetic relationships and the molecular differences among ILTV strains from different geographic regions.

Mucin-like Region of Herpes Simplex Virus Type 1 Attachment Protein Glycoprotein C (gC) Modulates the Virus-Glycosaminoglycan Interaction

Glycoprotein C (gC) mediates the attachment of HSV-1 to susceptible host cells by interacting with glycosaminoglycans (GAGs) on the cell surface. gC contains a mucin-like region located near the GAG-binding site, which may affect the binding activity. Here, we address this issue by studying a HSV-1 mutant lacking the mucin-like domain in gC and the corresponding purified mutant protein (gCΔmuc) in cell culture and GAG-binding assays, respectively. The mutant virus exhibited two functional alterations as compared with native HSV-1 (i.e. decreased sensitivity to GAG-based inhibitors of virus attachment to cells and reduced release of viral particles from the surface of infected cells). Kinetic and equilibrium binding characteristics of purified gC were assessed using surface plasmon resonance-based sensing together with a surface platform consisting of end-on immobilized GAGs. Both native gC and gCΔmuc bound via the expected binding region to chondroitin sulfate and sulfated hyaluronan but not to the non-sulfated hyaluronan, confirming binding specificity. In contrast to native gC, gCΔmuc exhibited a decreased affinity for GAGs and a slower dissociation, indicating that once formed, the gCΔmuc-GAG complex is more stable. It was also found that a larger number of gCΔmuc bound to a single GAG chain, compared with native gC. Taken together, our data suggest that the mucin-like region of HSV-1 gC is involved in the modulation of the GAG-binding activity, a feature of importance both for unrestricted virus entry into the cells and release of newly produced viral particles from infected cells.

Dissection of the antibody response against herpes simplex virus glycoproteins in naturally infected humans

Relatively little is known about the extent of the polyclonal antibody (PAb) repertoire elicited by herpes simplex virus (HSV) glycoproteins during natural infection and how these antibodies affect virus neutralization. Here, we examined IgGs from 10 HSV-seropositive individuals originally classified as high or low virus shedders. All PAbs neutralized virus to various extents. We determined which HSV entry glycoproteins these PAbs were directed against: glycoproteins gB, gD, and gC were recognized by all sera, but fewer sera reacted against gH/gL. We previously characterized multiple mouse monoclonal antibodies (MAbs) and mapped those with high neutralizing activity to the crystal structures of gD, gB, and gH/gL. We used a biosensor competition assay to determine whether there were corresponding human antibodies to those epitopes. All 10 samples had neutralizing IgGs to gD epitopes, but there were variations in which epitopes were seen in individual samples. Surprisingly, only three samples contained neutralizing IgGs to gB epitopes. To further dissect the nature of these IgGs, we developed a method to select out gD- and gB-specific IgGs from four representative sera via affinity chromatography, allowing us to determine the contribution of antibodies against each glycoprotein to the overall neutralization capacity of the serum. In two cases, gD and gB accounted for all of the neutralizing activity against HSV-2, with a modest amount of HSV-1 neutralization directed against gC. In the other two samples, the dominant response was to gD.

IMPORTANCE

Antibodies targeting functional epitopes on HSV entry glycoproteins mediate HSV neutralization. Virus-neutralizing epitopes have been defined and characterized using murine monoclonal antibodies. However, it is largely unknown whether these same epitopes are targeted by the humoral response to HSV infection in humans. We have shown that during natural infection, virus-neutralizing antibodies are principally directed against gD, gB, and, to a lesser extent, gC. While several key HSV-neutralizing epitopes within gD and gB are commonly targeted by human serum IgG, others fail to induce consistent responses. These data are particularly relevant to the design of future HSV vaccines.

Prevention and management of neonatal herpes simplex virus infections

Human herpes simplex virus (HSV) infection in neonates can result in devastating outcomes, including mortality and significant morbidity. All infants are potentially at risk for neonatal HSV infection. This position statement reviews epidemiology, transmission and risk factors, with a focus on intrapartum infection. It considers diagnosis and prognosis according to infection category, along with testing modalities and limitations. Recommendations for managing newborns known to have been exposed intrapartum to HSV are based on expert opinion because a randomized trial to compare management options is not feasible. Guidance is provided for the empirical management of infants with suspected clinical sepsis, including those who do not respond to antibacterial therapy. The present statement replaces a 2006 position statement by the Canadian Paediatric Society.

Antibody-based concepts for multipurpose prevention technologies

Because of the versatility and specificity of monoclonal antibodies, they are candidates for multipurpose prevention technologies when formulated as topical (gels, films, rings) or injectable drugs and as vaccines. This review focuses on antibody-based proof of concept studies for the human immunodeficiency virus, herpes simplex virus and sperm. Opportunities and challenges in antibody evasion/resistance, manufacturing, regulatory, and pharmacoeconomics are discussed. This article is based on a presentation at the "Product Development Workshop 2013: HIV and Multipurpose Prevention Technologies," held in Arlington, Virginia on February 21-22, 2013. It forms part of a special supplement to Antiviral Research.

Varicella vaccination alters the chronological trends of herpes zoster and varicella

Background

Population studies on trends of varicella and herpes zoster (HZ) associated with varicella zoster vaccination and climate is limited.

Methods

This study used insurance claims data to investigate the chronological changes in incident varicella and HZ associated with varicella zoster vaccination. Poisson regression was used to estimate the occurrence of varicella associated with the occurrence of HZ and vice versa by year, season, sex, temperature, and sunny hours.

Results

The varicella incidence declined from 7.14 to 0.76 per 1,000 person-years in 2000–2009, whereas the HZ incidence increased from 4.04 to 6.24 per 1,000 person-years. Females tended to have a higher risk than men for HZ (p<0.0001) but not varicella. The monthly mean varicella incidence was the lowest in September (160 cases) and the highest in January (425 cases), while the mean HZ incidence was lower in February (370 cases) and higher in August (470 cases). HZ was negatively associated with the incidence of varicella before and after the varicella zoster vaccination (p<0.001), increased 1.6% within one week post-vaccination. The effect of temperature on HZ was attenuated by 18.5% (p<0.0001) in association with vaccination. The varicella risk was positively associated with sun exposure hours, but negatively associated with temperature only before vaccination.

Conclusions

The varicella vaccination is effective in varicella prevention, but the incidence of HZ increases after vaccination. HZ has a stronger association with temperature and UV than with seasonality while varicella risk associated with temperature and UV is diminished.

Complete genome sequence of the first Chinese virulent infectious laryngotracheitis virus

Infectious laryngotracheitis (ILT) is an acute respiratory disease caused by infectious laryngotracheitis virus (ILTV). The complete genome sequences of five attenuated ILTV vaccine strains and six virulent ILTV strains as well as two Australian ILTV field strains have been published in Australia and the USA so far. To provide the complete genome sequence information of ILTVs from different geographic regions, the whole genome of ILTV LJS09 isolated in China was sequenced. The genome of ILTV LJS09 was 153,201 bp in length, and contained 79 ORFs. Most of the ORFs had high sequence identity with homologous ORFs of reference strains. There was a large fragment deletion within the noncoding region of unique long region (UL) of ILTV LJS09 compared with SA2 and A20 strains. Though the origin binding protein of ILTV LJS09 existed, there was no AT-rich region in strain LJS09. Alignments of the amino acid sequences revealed seven mutations at amino acids 71 (Arg → Lys), 116 (Ala → Val), 207 (Thr → Ile) and 644 (Thr → Ile) on glycoprotein B, 155 (Phe → Ser) and 376 (Arg → His) on glycoprotein D and 8 (Gln→Pro) on glycoprotein L of ILTV LJS09 compared to those of virulent strain (USDA) as ILTV LJS09 did not grow on chicken embryo fibroblasts, suggesting the role of the key seven amino acids in determination of the cell tropism of ILTV LJS09. This is the first complete genome sequence of the virulent strain of ILTV in Asia using the conventional PCR method, which will help to facilitate the future molecular biological research of ILTVs.

Distribution characteristics of DNA vaccine encoded with glycoprotein C from Anatid herpesvirus 1 with chitosan and liposome as deliver carrier in ducks

Background

A eukaryotic expression plasmid encoding glycoprotein C (gC) of Anatid herpesvirus 1 (AnHV-1) (pcDNA3.1-gC) was constructed and validated. The tissue distribution of chitosan/DNA complexes, liposome/DNA complexes and pcDNA3.1-gC alone were evaluated using a quantitative real-time PCR based TaqMan™ probe following intramuscular administration in ducklings.

Results

Compared with pcDNA3.1-gC alone, liposomes universally increased the plasmid DNA copy number at the injection sites, liver, spleen, heart, brain, bursa of Fabricius, and especially in the enteron (esophagus, duodenum, rectum, and cecum). Chitosan also universally increased the plasmid DNA copy number at the injection sites, liver, spleen, heart, brain and esophagus. Compared with lipoplex-gC, higher chitosan-gC plasmid DNA copy numbers were detected at the injection sites, liver, spleen, heart, brain and esophagus. In contrast, compared with lipoplex-gC, lower copy numbers of chitosan-gC plasmid DNA were detected in the duodenum, rectum and cecum.

Conclusions

The results of this study demonstrated that chitosan and liposomes mediated rapid and extensive plasmid distribution in duck tissues, with low levels maintained from 1 d after DNA vaccination.

Serologic analysis of the IgG antibody response in children with varicella zoster virus wild-type infection and vaccination

INTRODUCTION

In contrast to varicella zoster virus (VZV) primary infection, VZV vaccination does not seem to provide lifelong immunity against varicella. Because more people get vaccinated every year, the development of sensitive serological test systems for the detection of protective anti-VZV IgG will become important in the future.

METHODS

We have previously developed a novel VZV line assay based on 5 different recombinant VZV antigens. In this study, we compared this novel assay with a commercially available glycoprotein enzyme immunoassay (RIDASCREEN VZV IgG) in detecting anti-VZV IgG of children with previous varicella infection and VZV vaccination.

RESULTS

One hundred twenty-five children were included in this study, 72 with a history of varicella infection and 53 with VZV vaccination. Both assays detected anti-VZV IgG antibodies in both study groups with similar sensitivities. The VZV line assay revealed striking differences in the anti-VZV IgG composition against the VZV open reading frames, 4, 14 and 49, between both study groups, indicating that wild-type varicella infection causes a more diverse immune response against VZV than does vaccination. The exploitation of these results enabled the discrimination of both study groups with a sensitivity of 0.93 and a specificity of 0.83, indicating that the serologic differentiation of children with previous varicella infection and VZV vaccination might be possible.

CONCLUSION

The VZV line assay enables the detection of anti-VZV IgG with sensitivities comparable to glycoprotein enzyme immunoassays and might be suitable for the serologic discrimination between children with a history of varicella infection and VZV vaccination.

Discovery of potential diagnostic and vaccine antigens in herpes simplex virus 1 and 2 by proteome-wide antibody profiling

Routine serodiagnosis of herpes simplex virus (HSV) infections is currently performed using recombinant glycoprotein G (gG) antigens from herpes simplex virus 1 (HSV-1) and HSV-2. This is a single-antigen test and has only one diagnostic application. Relatively little is known about HSV antigenicity at the proteome-wide level, and the full potential of mining the antibody repertoire to identify antigens with other useful diagnostic properties and candidate vaccine antigens is yet to be realized. To this end we produced HSV-1 and -2 proteome microarrays in Escherichia coli and probed them against a panel of sera from patients serotyped using commercial gG-1 and gG-2 (gGs for HSV-1 and -2, respectively) enzyme-linked immunosorbent assays. We identified many reactive antigens in both HSV-1 and -2, some of which were type specific (i.e., recognized by HSV-1- or HSV-2-positive donors only) and others of which were nonspecific or cross-reactive (i.e., recognized by both HSV-1- and HSV-2-positive donors). Both membrane and nonmembrane virion proteins were antigenic, although type-specific antigens were enriched for membrane proteins, despite being expressed in E. coli.

Complete genome sequence of virulent duck enteritis virus (DEV) strain 2085 and comparison with genome sequences of virulent and attenuated DEV strains

We here report the complete genome sequence of the duck enteritis virus (DEV) wild-type strain 2085, an avian herpesvirus (GenBank ID: JF999965). The nucleotide sequence was derived from the 2085 genome cloned as an infectious bacterial artificial chromosome (BAC) clone. The DEV 2085 genome is 160,649-bp in length and encodes 78 predicted open reading frames (ORFs), a number identical to that identified for the attenuated DEV VAC strain (GenBank ID: EU082088.2). Comparison of the genome sequences DEV 2085 and VAC with partial sequences of the virulent CHv strain and the attenuated strain Clone-03 was carried out to identify nucleotide or amino acid polymorphisms that potentially contribute to DEV virulence. No amino acid changes were identified in 24 of the 78 ORFs, a result indicating high conservation in DEV independently of strain origin or virulence. In addition, 39 ORFs contain non-synonymous nucleotide substitutions, while 15 ORFs had nucleotide insertions or deletions, frame-shift mutations and/or non-synonymous nucleotide substitutions with an effect on ORF initiation or termination. In 7 of the 15 ORFs with high and 27 of the 39 ORFs with low variability, polymorphisms were exclusively found in DEV 2085, a finding that likely is a result of a different origin of 2085 (Europe) or VAC, Clone-03 and CHv (Eastern Asia). Five ORFs (UL2, UL12, US10, UL47 and UL41) with polymorphisms were identical between the virulent DEV 2085 and CHv but different from VAC or Clone-03. They, individually or in combination, may therefore represent DEV virulence factors. Our comparative analysis of four DEV sequences provides a comprehensive overview of DEV genome structure and identifies ORFs that are changed during serial virus passage.