CD4+ T-cell responses to herpes simplex virus type 2 (HSV-2) glycoprotein G are type specific and differ in symptomatic and asymptomatic HSV-2-infected individuals

A truncated glycoprotein G vaccine formulated with Advax-CpG adjuvant provides protection of mice against genital herpes simplex virus 2 infection

Herpes simplex virus type 2 (HSV-2) is a common sexually transmitted disease that affects approximately 500 million individuals globally. There is currently no approved vaccine to prevent HSV-2 infection. EXCT4 is a truncated form of the mature glycoprotein G-2 (mgG-2) that unlike full mature form is secreted by expressing cells enabling it to be rapidly scaled up for production. The current study examined whether EXCT4 immunity in mice could be further enhanced through use of adjuvants. EXCT4 formulated with Advax-CpG adjuvant induced a strong Th1-type immune response characterized by interferon gamma (IFN-γ) and protected animals against a lethal genital challenge with HSV-2. This response was associated with reduced viral load in vaginal washes, spinal cord, and dorsal root ganglia. Together the results provide proof of concept that EXCT4 formulated with Advax-CpG adjuvant is a promising HSV-2 vaccine candidate warranting further investigation.

Associations of Viral Seroreactivity with AIDS-Related Non-Hodgkin Lymphoma

Infection with human immunodeficiency virus (HIV) is associated with substantially increased incidence of non-Hodgkin lymphoma (NHL). This risk may be driven, in part, by reduced immune control over viral infections in the setting of acquired immunodeficiency syndrome (AIDS), although the lymphomagenic mechanisms are not yet established. We used bead-based multiplex assays to measure antibody seroreactivity to 32 viral antigens representing 22 different viral infections (human herpesviruses 1-8, hepatitis B and C virus, human T-lymphotropic virus type-1, and human polyomaviruses) in two prospective HIV cohorts. Incident (n = 28) and prevalent (n = 38) AIDS-related NHL cases were matched by age, sex, race, and CD4 count to 67 HIV-positive control individuals without AIDS-NHL. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations of AIDS-NHL with the number of different viruses to which an individual was seropositive and seroreactivity to individual antigens. Seropositivity to an increasing number of viruses was inversely associated with AIDS-NHL (OR per virus = 0.84, 95% CI = 0.72-0.98). Seroreactivity to herpes simplex virus 2 2mgG unique antigen (OR = 0.47; 95% CI = 0.23-0.97) and to WU polyomavirus viral capsid protein (OR = 0.26, 95% CI = 0.10-0.65) was significantly lower in AIDS-NHL cases compared to controls. In this evaluation of antibodies to multiple viruses, we observed an inverse association between seropositivity to a larger number of viruses and AIDS-NHL. While in need of further evaluation, our data raise the novel hypothesis that insufficient exposures or impaired humoral immune responses to viral infections may be associated with AIDS-related lymphomagenesis.

HSV-2 Infection of Human Genital Epithelial Cells Upregulates TLR9 Expression Through the SP1/JNK Signaling Pathway

It is known that herpes simplex virus type 2 (HSV-2) triggers the activation of Toll-like receptor (TLR) 9 signaling pathway and the consequent production of antiviral cytokines in dendritic cells. However, the impact of HSV-2 infection on TLR9 expression and signaling in genital epithelial cells, the primary HSV-2 targets, has yet to be determined. In the current study, by using both human genital epithelial cell lines and primary genital epithelial cells as models, we found that HSV-2 infection enhances TLR9 expression at both mRNA and protein levels. Such enhancement is virus replication-dependent and CpG-independent, while the HSV-2-mediated upregulation of TLR9 does not activate TLR9 signaling pathway. Mechanistically, a SP1 binding site on TLR9 promoter appears to be essential for HSV-2-induced TLR9 transactivation. Upon HSV-2 infection, SP1 translocates from the cytoplasm to the nucleus, and consequently binds to TLR9 promoter. By using specific inhibitors, the JNK signaling pathway is shown to be involved in the HSV-2-induced TLR9 transactivation, while HSV-2 infection increases the phosphorylation but not the total level of JNK. In agreement, antagonism of JNK signaling pathway inhibits the HSV-2-induced SP1 nuclear translocation. Taken together, our study demonstrates that HSV-2 infection of human genital epithelial cells promotes TLR9 expression through SP1/JNK signaling pathway. Findings in this study provide insights into HSV-2-host interactions and potential targets for immune intervention.

Herpes simplex virus specific T cell response in a cohort with primary genital infection correlates inversely with frequency of subsequent recurrences

OBJECTIVES

During the last decades, a changing epidemiological pattern of genital herpes simplex virus (HSV) infection has emerged. Primary infection is now caused as often by HSV-1 as by HSV-2. Once established, HSV can be reactivated leading to recurrent mucocutaneous lesions as well as meningitis. Why some otherwise immune-competent individuals experience severe and frequent recurrences is not known, and the immunological mechanism underlying recurrent symptomatic HSV infection is not fully understood. In this study, we investigate and characterise the immune response of patients with first episode of HSV genital infection and its relation to the frequency of symptomatic recurrences.

METHODS

In this cohort study, clinical and immunological data were collected from 29 patients who were followed 1 year after presenting with a first episode of genital or meningeal HSV infection. They were classified by PCR and serology as those with primary HSV-1, primary HSV-2 and non-primary HSV-2 infection.

RESULTS

HSV-specific interleukin(Il)-4 and Il-10 responses at first visit were higher in primary infected HSV-2 infected patients experiencing lower numbers of recurrences during subsequent year.

CONCLUSIONS

The median number of recurrences following primary HSV-2 genital infection may partly be predicted by the strength of an early HSV-specific IL-4 and IL-10 response.

Vaccination with the Secreted Glycoprotein G of Herpes Simplex Virus 2 Induces Protective Immunity after Genital Infection

Herpes simplex virus 2 (HSV-2) infects the genital mucosa and establishes a life-long infection in sensory ganglia. After primary infection HSV-2 may reactivate causing recurrent genital ulcerations. HSV-2 infection is prevalent, and globally more than 400 million individuals are infected. As clinical trials have failed to show protection against HSV-2 infection, new vaccine candidates are warranted. The secreted glycoprotein G (sgG-2) of HSV-2 was evaluated as a prophylactic vaccine in mice using two different immunization and adjuvant protocols. The protocol with three intramuscular immunizations combining sgG-2 with cytosine-phosphate-guanine dinucleotide (CpG) motifs and alum induced almost complete protection from genital and systemic disease after intra-vaginal challenge with HSV-2. Robust immunoglobulin G (IgG) antibody titers were detected with no neutralization activity. Purified splenic CD4+ T cells proliferated and produced interferon-γ (IFN-γ) when re-stimulated with the antigen in vitro. sgG-2 + adjuvant intra-muscularly immunized mice showed a significant reduction of infectious HSV-2 and increased IFN-γ levels in vaginal washes. The HSV-2 DNA copy numbers were significantly reduced in dorsal root ganglia, spinal cord, and in serum at day six or day 21 post challenge. We show that a sgG-2 based vaccine is highly effective and can be considered as a novel candidate in the development of a prophylactic vaccine against HSV-2 infection.

Tissue-resident memory T cells in cytomegalovirus infection

Herpesviruses establish life-long infection in their hosts and maintain latent reservoirs for sporadic reactivation at peripheral sites, such as skin and mucosae. For herpes simplex virus infection, experimental studies in mice revealed that immediate protection against local reactivation or superinfection events in the skin relies on tissue resident memory T cells (TRM) rather than on their circulating counterparts. Recent evidence extends this notion to cytomegalovirus infection, which potently induces TRM cells in both mice and humans particularly in mucosal tissues that constitute important viral sanctuaries and are relevant entry sites for challenge and superinfections. The discovery unravels promising opportunities to exploit cytomegalovirus based vaccine vectors for the specific induction of tissue resident T cell subsets.

Mucosal resident memory CD4 T cells in protection and immunopathology

Tissue-resident memory T cells (TRM) comprise a newly defined subset, which comprises a major component of lymphocyte populations in diverse peripheral tissue sites, including mucosal tissues, barrier surfaces, and in other non-lymphoid and lymphoid sites in humans and mice. Many studies have focused on the role of CD8 TRM in protection; however, there is now accumulating evidence that CD4 TRM predominate in tissue sites, and are integral for in situ protective immunity, particularly in mucosal sites. New evidence suggests that mucosal CD4 TRM populations differentiate at tissue sites following the recruitment of effector T cells by local inflammation or infection. The resulting TRM populations are enriched in T-cell specificities associated with the inducing pathogen/antigen. This compartmentalization of memory T cells at specific tissue sites may provide an optimal design for future vaccination strategies. In addition, emerging evidence suggests that CD4 TRM may also play a role in immunoregulation and immunopathology, and therefore, targeting TRM may be a viable therapeutic approach to treat inflammatory diseases in mucosal sites. This review will summarize our current understanding of CD4 TRM in diverse tissues, with an emphasis on their role in protective immunity and the mechanisms by which these populations are established and maintained in diverse mucosal sites.

Novel deletion in glycoprotein G forms a cluster and causes epidemiologic spread of herpes simplex virus type 2 infection

The herpes simplex virus type 2 (HSV-2) glycoprotein G (gG-2) gene of 106 clinical isolates was analyzed and six isolates were identified with 63 nucleotides comprising 21 amino acids (aa) deleted in the immunodominant region. Compared with strain HG52, variations in the gG-2 gene were found at 276 and 27 sites in nucleotide and aa sequences, respectively, in the 106 strains. Significant variations in both nucleotides and aa were accumulated in the immunodominant region rather than in the other regions (P < 0.001), indicating that the immunodominant region might be indispensable in vivo and a hot spot for variation. The frequency of 21 aa-deleted strains (HSVΔ21/gG-2) among clinical isolates was 5%, indicating the advantage of this deletion of gG-2 for epidemiological expansion. Phylogenetic analysis of the 106 strains indicated that the HSVΔ21/gG-2 strains formed a cluster among the various variations but that their genomes showed different endonuclease digestion patterns. The antibody titers to total HSV antigens of patients infected with wild HSV-2 and HSVΔ21/gG-2 were similar, but patients with HSVΔ21/gG-2 had a lower antibody titer to gG-2 than those with wild HSV-2 (P < 0.001). HSVΔ21/gG-2 might be less immnunogenic and reduce antibody production to gG-2, while its pathogenicity in humans was not distinguished in its clinical manifestations. Thus, infection with HSVΔ21/gG-2 caused genital lesions similar to wild HSV-2 infection, but evaded the immune response to gG-2 to allow epidemiological spread, indicating the importance of this deletion in the immunodominant region of gG-2 in the pathogenesis and transmission of genital herpes.

Mucosal herpes immunity and immunopathology to ocular and genital herpes simplex virus infections

Herpes simplex viruses type 1 and type 2 (HSV-1 and HSV-2) are amongst the most common human infectious viral pathogens capable of causing serious clinical diseases at every stage of life, from fatal disseminated disease in newborns to cold sores genital ulcerations and blinding eye disease. Primary mucocutaneous infection with HSV-1 & HSV-2 is followed by a lifelong viral latency in the sensory ganglia. In the majority of cases, herpes infections are clinically asymptomatic. However, in symptomatic individuals, the latent HSV can spontaneously and frequently reactivate, reinfecting the muco-cutaneous surfaces and causing painful recurrent diseases. The innate and adaptive mucosal immunities to herpes infections and disease remain to be fully characterized. The understanding of innate and adaptive immune mechanisms operating at muco-cutaneous surfaces is fundamental to the design of next-generation herpes vaccines. In this paper, the phenotypic and functional properties of innate and adaptive mucosal immune cells, their role in antiherpes immunity, and immunopathology are reviewed. The progress and limitations in developing a safe and efficient mucosal herpes vaccine are discussed.

STAT4 regulates antiviral gamma interferon responses and recurrent disease during herpes simplex virus 2 infection

STAT4 is an important transcription factor that contributes to the incidence and severity of different autoimmune diseases and is implicated in the antiviral immune responses in mice. In this study, we evaluated the role of STAT4 in human and murine herpes simplex virus 2 (HSV-2) infections. We show that STAT4 regulates antiviral gamma interferon (IFN-γ) responses and disease severity during chronic HSV-2 infections in humans and vaccine-induced IFN-γ-mediated protection against HSV-2 infection in mice. In a cohort of 228 HSV-2-infected individuals, representing both patients with recurrent disease and asymptomatic HSV-2 carriers, we found that genetic variations in the STAT4 gene were associated with asymptomatic HSV-2 infection, as well as with increased in vitro secretion of IFN-γ in response to the virus. Mice that lacked STAT4 had impaired HSV-2-specific IFN-γ production and delayed-type hypersensitivity responses following vaccination, which led to impaired viral clearance in the genital tract of vaccinated animals after a genital HSV-2 challenge. We conclude that STAT4 plays an important role in IFN-γ-mediated HSV-2-specific immunity, affecting the severity of genital HSV-2 infection.

Herpes simplex virus type 2 infection of human epithelial cells induces CXCL9 expression and CD4+ T cell migration via activation of p38-CCAAT/enhancer-binding protein-β pathway

Recruitment of CD4(+) T cells to infection areas after HSV-2 infection may be one of the mechanisms that account for increased HIV-1 sexual transmission. Lymphocytes recruited by chemokine CXCL9 are known to be important in control of HSV-2 infection in mice, although the underlying mechanism remains to be addressed. Based on our observation that CXCL9 expression is augmented in the cervical mucus of HSV-2-positive women, in this study we demonstrate that HSV-2 infection directly induces CXCL9 expression in primary cervical epithelial cells and cell lines, the principal targets of HSV-2, at both mRNA and protein levels. Further studies reveal that the induction of CXCL9 expression by HSV-2 is dependent upon a binding site for C/EBP-β within CXCL9 promoter sequence. Furthermore, CXCL9 expression is promoted at the transcriptional level through phosphorylating C/EBP-β via p38 MAPK pathway, leading to binding of C/EBP-β to the CXCL9 promoter. Chemotaxis assays indicate that upregulation of CXCL9 expression at the protein level by HSV-2 infection enhances the migration of PBLs and CD4(+) T cells, whereas neutralization of CXCL9 or inhibition of p38-C/EBP-β pathway can significantly decrease the migration. Our data together demonstrate that HSV-2 induces CXCL9 expression in human cervical epithelial cells by activation of p38-C/EBP-β pathway through promoting the binding of C/EBP-β to CXCL9 promoter, which may recruit activated CD4(+) T cells to mucosal HSV-2 infection sites and potentially increase the risk of HIV-1 sexual transmission.

Glycoprotein G of herpes simplex virus 2 as a novel vaccine antigen for immunity to genital and neurological disease

The envelope glycoproteins of herpes simplex virus 1 (HSV-1) and HSV-2, with the exception of glycoprotein G, elicit cross-reactive B- and T-cell responses. Human vaccine trials, using the cross-reactive glycoproteins B and D, have shown no protection against genital HSV-2 infection or disease. In this study, the mature form of glycoprotein G (mgG-2) of HSV-2 was used for immunization of mice, either alone or in combination with adjuvant CpG, followed by an intravaginal challenge with a lethal dose of a fully virulent HSV-2 strain. Mice immunized with mgG-2 plus CpG showed low disease scores and a significantly higher survival rate (73%) than mice immunized with mgG-2 alone (20%) or controls (0%). Accordingly, limited numbers of infectious HSV-2 particles were detected in the spinal cord of mice immunized with mgG-2 plus CpG. The observed protection was associated with a gamma interferon (IFN-γ) response by splenic CD4(+) T cells upon antigen restimulation in vitro and in vaginal washes 1 day postinfection. The majority of sera collected from mice immunized with mgG-2 plus CpG showed macrophage-mediated antibody-dependent cellular cytotoxicity and antibody-dependent complement-mediated cytolysis, while no neutralization activity was observed. In conclusion, we have shown that immunization with the type-specific mgG-2 protein in combination with CpG could elicit protective immunity against an otherwise lethal vaginal HSV-2 challenge. The mgG-2 protein may therefore constitute a promising HSV-2 vaccine antigen to be considered for future human trials.

Polymorphisms in Toll-like receptor 3 confer natural resistance to human herpes simplex virus type 2 infection

Lack of Toll-like receptor 3 (TLR3) functional activity predisposes children to human herpesvirus 1 (HSV-1) encephalitis. In this study, we have investigated whether there is any link between TLR3 and adult HSV-2 infection by studying genetic variations in TLR3. The frequency of four single-nucleotide polymorphisms (SNPs) in the TLR3 gene in 239 patients with genital HSV-2 infection and 162 healthy controls, as well as the impact of these variants on TLR3 gene-expression levels, were compared. Two SNPs in the TLR3 gene (rs13126816 and rs3775291) were associated with a reduced incidence of HSV-2 infection. The minor allelic variants at both rs13126816 and rs3775291 were more common among healthy HSV-2-seronegative subjects than among HSV-2-infected individuals. This was even more apparent in HSV-1-seronegative individuals. There was, however, no association between any of the four TLR3 SNPs and HSV-2 disease severity, as they were expressed at similar proportions in asymptomatic and symptomatic HSV-2-infected patients alike. Furthermore, when assessing TLR3 mRNA expression in a limited number of HSV-2-infected individuals, we found that individuals carrying the homozygous genotypes for the minor alleles had significantly higher levels of TLR3 mRNA expression in peripheral blood mononuclear cells in response to HSV-2 stimulation than individuals that were homozygous for the major allele variants. Taken together, these results suggest that genetic variations in TLR3 may affect the susceptibility to HSV-2 infection in humans.

Future of an "Asymptomatic" T-cell Epitope-Based Therapeutic Herpes Simplex Vaccine

Considering the limited success of the recent herpes clinical vaccine trial [1], new vaccine strategies are needed. Infections with herpes simplex virus type 1 and type 2 (HSV-1 & HSV-2) in the majority of men and women are usually asymptomatic and results in lifelong viral latency in neurons of sensory ganglia (SG). However, in a minority of men and women HSV spontaneous reactivation can cause recurrent disease (i.e., symptomatic individuals). Our recent findings show that T cells from symptomatic and asymptomatic men and women (i.e. those with and without recurrences, respectively) recognize different herpes epitopes. This finding breaks new ground and opens new doors to assess a new vaccine strategy: mucosal immunization with HSV-1 & HSV-2 epitopes that induce strong in vitro CD4 and CD8 T cell responses from PBMC derived from asymptomatic men and women (designated here as "asymptomatic" protective epitopes") could boost local and systemic "natural" protective immunity, induced by wild-type infection. Here we highlight the rationale and the future of our emerging "asymptomatic" T cell epitope-based mucosal vaccine strategy to decrease recurrent herpetic disease.

Towards a rational design of an asymptomatic clinical herpes vaccine: the old, the new, and the unknown

The best hope of controlling the herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2) pandemic is the development of an effective vaccine. However, in spite of several clinical trials, starting as early as 1920s, no vaccine has been proven sufficiently safe and efficient to warrant commercial development. In recent years, great strides in cellular and molecular immunology have stimulated creative efforts in controlling herpes infection and disease. However, before moving towards new vaccine strategy, it is necessary to answer two fundamental questions: (i) why past herpes vaccines have failed? (ii) Why the majority of HSV seropositive individuals (i.e., asymptomatic individuals) are naturally "protected" exhibiting few or no recurrent clinical disease, while other HSV seropositive individuals (i.e., symptomatic individuals) have frequent ocular, orofacial, and/or genital herpes clinical episodes? We recently discovered several discrete sets of HSV-1 symptomatic and asymptomatic epitopes recognized by CD4(+) and CD8(+) T cells from seropositive symptomatic versus asymptomatic individuals. These asymptomatic epitopes will provide a solid foundation for the development of novel herpes epitope-based vaccine strategy. Here we provide a brief overview of past clinical vaccine trials, outline current progress towards developing a new generation "asymptomatic" clinical herpes vaccines, and discuss future mucosal "asymptomatic" prime-boost vaccines that could optimize local protective immunity.

Inhibition of γ-secretase cleavage in the notch signaling pathway blocks HSV-2-induced type I and type II interferon production

We have evaluated the role of γ-secretase, which is a crucial component in the Notch-induced signaling cascade, on herpes simplex virus type 2 (HSV-2)-induced innate and acquired interferon responses in human CD4(+) T cells and plasmacytoid dendritic cells (pDC). We found that blockade of the Notch signaling pathway with a pharmacological γ-secretase inhibitor blocked both HSV-2-induced interferon-γ (IFN-γ) production in CD4(+) T cells, and HSV-2-induced IFN-α production in pDC in a dose-dependent fashion. These effects were not due to an overall suppressive capacity of the γ-secretase inhibitor, as it affected neither phytohemagglutinin (PHA)-induced IFN-γ production in CD4(+) T cells, nor CpG-induced IFN-α production in pDC. Our data suggest that Notch signaling could be involved in HSV-2-induced interferon responses in CD4(+) T-cells and pDC.

Detection and description of a particular Ostreid herpesvirus 1 genotype associated with massive mortality outbreaks of Pacific oysters, Crassostrea gigas, in France in 2008

Ostreid herpesvirus 1 (OsHV-1) infections have been reported around the world and are associated with high mortalities of the Pacific oyster (Crassostrea gigas). In the summer 2008, abnormal mortality rates ranging from 80% to 100% were reported in France and affected only Pacific oysters. Analyses of oyster samples collected during mortality outbreaks demonstrated a significant detection of OsHV-1 (75% of analysed batches), which appeared stronger than previous years. DNA sequencing based on C and IA regions was carried out on 28 batches of OsHV-1 infected Pacific oysters collected in 2008. Polymorphisms were described in both the C and IA regions and characterized a genotype of OsHV-1 not already reported and termed OsHV-1 microVar. A microsatellite zone present in the C region showed several deletions. Additionally, 44 isolates collected in France and in the USA, from 1995 to 2007 were sequenced and compared to the 2008 sequences. The analyses of 76 sequences showed OsHV-1 microVar detection only in 2008 isolates. These data suggest that OsHV-1 microVar can be assumed as an emergent genotype.

A 3'-untranslated region polymorphism in the TBX21 gene encoding T-bet is a risk factor for genital herpes simplex virus type 2 infection in humans

It was recently shown that the transcription factor T-bet is crucial for adequate innate and acquired immune responses to genital herpes simplex virus type 2 (HSV-2) infection in mice. To test the possible genetic influence of variations in the TBX21 gene encoding T-bet on susceptibility to infection, this study evaluated the frequencies of five different single-nucleotide polymorphisms (SNPs) in the human TBX21 gene in 159 HSV-2-infected individuals and compared them with those in 186 healthy HSV-2-seronegative controls. The data showed that one variation (rs17244587) in the 3'-untranslated region of TBX21 was strongly associated with the incidence of genital HSV-2 infection. The frequency of the A allele at this position was 0.19 in the group of HSV-2-infected individuals compared with 0.05 in the group of uninfected controls (P=9.3x10(-8)). Furthermore, a homozygous AA genotype was found only among HSV-2-infected individuals and not in seronegative controls. These results indicate that the host genetic background may affect susceptibility to HSV-2 infection in humans, with TBX21 as a strong candidate gene.

Asymptomatic human CD4+ cytotoxic T-cell epitopes identified from herpes simplex virus glycoprotein B

The identification of "asymptomatic" (i.e., protective) epitopes recognized by T cells from herpes simplex virus (HSV)-seropositive healthy individuals is a prerequisite for an effective vaccine. Using the PepScan epitope mapping strategy, a library of 179 potential peptide epitopes (15-mers overlapping by 10 amino acids) was identified from HSV type 1 (HSV-1) glycoprotein B (gB), an antigen that induces protective immunity in both animal models and humans. Eighteen groups (G1 to G18) of 10 adjacent peptides each were first screened for T-cell antigenicity in 38 HSV-1-seropositive but HSV-2-seronegative individuals. Individual peptides within the two immunodominant groups (i.e., G4 and G14) were further screened with T cells from HLA-DR-genotyped and clinically defined symptomatic (n = 10) and asymptomatic (n = 10) HSV-1-seropositive healthy individuals. Peptides gB(161-175) and gB(166-180) within G4 and gB(661-675) within G14 recalled the strongest HLA-DR-dependent CD4(+) T-cell proliferation and gamma interferon production. gB(166-180), gB(661-675), and gB(666-680) elicited ex vivo CD4(+) cytotoxic T cells (CTLs) that lysed autologous HSV-1- and vaccinia virus (expressing gB)-infected lymphoblastoid cell lines. Interestingly, gB(166-180) and gB(666-680) peptide epitopes were strongly recognized by CD4(+) T cells from 10 of 10 asymptomatic patients but not by CD4(+) T cells from 10 of 10 symptomatic patients (P < 0.0001; analysis of variance posttest). Inversely, CD4(+) T cells from symptomatic patients preferentially recognized gB(661-675) (P < 0.0001). Thus, we identified three previously unrecognized CD4(+) CTL peptide epitopes in HSV-1 gB. Among these, gB(166-180) and gB(666-680) appear to be "asymptomatic" peptide epitopes and therefore should be considered in the design of future herpes vaccines.

Role of IFN-alpha/beta signaling in the prevention of genital herpes virus type 2 infection

This study has shown that IFN-alpha/beta signaling is crucial for combating primary herpes simplex virus type 2 (HSV-2) infection and for responding to immunotherapy using ligands to TLR3, 7 and 9, but not for vaccine-induced immunity. Both genital viral replication and the disease progression were enhanced in HSV-2-infected mice lacking the IFN-alpha/beta receptor (IFN-alpha/betaR-/-). IFN-alpha/betaR-/- mice were, however, able to mount a normal HSV-2-specific Th1 response and acquired sterilizing immunity following vaccination. Anti-viral treatments using agonists to TLR3, 7 and 9 by administration of synthetic dsRNA, imiquimod and oligonucleotides containing unmethylated CpG motifs, respectively, were strongly dependent on IFN-alpha/beta receptor signaling for their efficacy. Even though all treatments had a weak impact on local vaginal viral replication in infected IFN-alpha/betaR-/- animals, they did not affect disease progression or mortality in these animals as opposed to wild type controls where all three treatments reduced viral replication as well as disease severity and mortality. Lack of IFN-alpha/betaR signaling also blocked production of IFN-gamma and TNF-alpha in response to TLR9 activation. These studies have shown that IFN-alpha/beta receptor signaling is important for multiple events in the anti-viral defense.

Minimal change in HSV-2 seroreactivity: a cross-sectional Swedish population study

The prevalence of antibodies to herpes simplex virus type 2 (HSV-2) was determined in sera collected from 2 Swedish cross-sectional populations during 1990/91 and 1996/97. A glycoprotein G2 (gG-2) peptide ELISA was used to analyse 2899 sera from adults. We found a prevalence of 13.0% in 18-70-y-olds in 1990/91 and 16.4% in 31-55-y-olds in 1996/97. Seropositivity to HSV-2 was somewhat higher in women than in men; 14.4% compared to 11.6% in 1990/91 and 18.9% compared to 13.6% in 1996/97. Overall there was a significant difference in female prevalence of HSV-2 compared to prevalence in males of the same age groups (p=0.013). Total antibody prevalence to HSV-1 of 88% in HSV-2 negative individuals above 18 y of age was found. HSV-2 positive individuals were found seropositive to HSV-1 in approximately 95% of the cases. 12% were negative for both HSV-1 and HSV-2 antibodies. In addition, there was no serological sign that the reported increase of HSV-1 as an early sexual disease had reduced the frequency of HSV-2 seropositivity in the sexually most active age groups. In conclusion, our investigation has shown no significant increase of HSV-2 seroprevalence in randomly selected Swedish subjects during the defined time period.

Neurokinin 1 receptor signaling affects the local innate immune defense against genital herpes virus infection

We show that genital infection with neurotropic HSV type 2 (HSV-2) induced a significant increase of the neuropeptide substance P (SP) within the genital tract of mice. SP was shown to weakly interfere with the HSV-2 replication. Furthermore, lack of SP signaling through the use of mice deficient in the SP receptor, neurokinin 1 receptor (NK1R), revealed an important role for SP in the innate defense against HSV-2. NK1R-deficient mice had significantly enhanced levels of HSV-2 in the genital tract and in the CNS following infection and a significantly accelerated disease progression, which was associated with an impaired NK cell activity locally in the vagina. Lack of NK1R signaling did, however, not impair the animals' ability to mount a protective immune response to HSV-2 following vaccination with an attenuated virus. Both NK1R+/+ and NK1R-/- mice developed strong HSV-2-specific Th1 T cell responses following vaccination. No genital viral replication was observed in either vaccinated NK1R-deficient or NK1R+/+ control animals following a genital HSV-2 challenge, and all of these animals survived without any symptoms of disease. In conclusion, the present results indicate that SP and NK1R signaling contributes to the innate resistance against HSV-2 infection in mice.

CD8+ T-Cells Suppress Antigen-Specific and Allogeneic CD4+ T-Cell Responses to Herpes Simplex Virus Type 2–Infected Human Dendritic Cells

In this study we show that human dendritic cells (DC), productively infected with herpes simplex virus type 2 (HSV-2), activate CD8+ T cells that suppress antigen-specific and alloreactive CD4+ T cell expansion. Addition of CD8+ T cells to cultures of DC and CD4+ T cells blocked CD4+ T-cell proliferation in response to HSV-2-infected but not to uninfected DC. The effect was independent of prior HSV exposure or cognate MHC class I-restricted CD8-DC recognition as it was induced in CD8+ T cells from HSV-2-seronegative individuals and in mixed lymphocyte reactions using allogeneic DC. Both CD8+ CD25+ and CD8+ CD25- cells were shown to have suppressive capacities. The blood-derived CD25+ CD8+ T cells did not express Foxp3 mRNA but had a bona fide antiproliferative capacity in response to both uninfected and HSV-2-infected DC, whereas the CD25-CD8+ T cells were selectively activated to become antiproliferative by HSV-2-infected DC. These data imply that HSV infection of DC could modulate the immune response by activating CD8+ T cells.

Protective immunity to genital herpes simplex [correction of simpex] virus type 2 infection is mediated by T-bet

We show, for the first time, that the transcription factor T-bet, which is implicated in IFN-gamma production, is required for the induction of vaccine-induced antiviral immune protection. T-bet was found to be important in both the innate and acquired immune protection against genital HSV-2 infection. T-bet(-/-) and T-bet(+/+) mice were infected vaginally with HSV-2 and examined daily for disease and mortality. T-bet(-/-) mice had significantly higher virus titers than T-bet(+/+) mice following a primary HSV-2 infection, and succumbed significantly earlier to the infection. This result was associated with an impaired NK cell cytotoxic capacity and NK cell-mediated IFN-gamma production in the T-bet(-/-) mice. To assess the induction of acquired antiviral immune protection, mice were vaccinated with an attenuated virus before infection. Vaccinated T-bet(-/-) mice could not control viral replication following an HSV-2 challenge and had significantly higher virus titers and mortality rates than vaccinated T-bet(+/+) mice that remained healthy. The impaired acquired immune protection in T-bet(-/-) mice was associated with a significantly decreased HSV-2-specific delayed-type hypersensitivity response and a significantly reduced HSV-2-specific IFN-gamma production from CD4(+) T cells. However, T-bet deficiency did not impair either the IFN-gamma production or the cytotoxic capacity of HSV-2-specific CD8(+) T cells. We conclude that T-bet plays a crucial role in both the innate defense and the generation of vaccine-induced immunity against genital HSV-2 infection in mice.

A proinflammatory peptide from herpes simplex virus type 2 glycoprotein G affects neutrophil, monocyte, and NK cell functions

We have identified a synthetic peptide derived from the secreted portion of HSV type 2 glycoprotein G, denoted gG-2p20, which has proinflammatory properties in vitro. The gG-2p20 peptide, corresponding to aa 190-205 of glycoprotein G-2, was a chemoattractant for both monocytes and neutrophils in a dose-dependent fashion, and also induced the release of reactive oxygen from these cells. The receptor mediating the responses was identified as the formyl peptide receptor. The gG-2p20-induced activation of phagocytes had a profound impact on NK cell functions. The reactive oxygen species produced by gG-2p20-activated phagocytes both inhibited NK cell cytotoxicity and accelerated the apoptotic cell death in NK cell-enriched lymphocyte populations. Hence, we have for the first time been able to identify a potential function of the secreted portion of HSV-2 glycoprotein G. We propose that the proinflammatory gG-2p20 peptide identified could contribute to a reduced function and viability of NK cells during HSV-2 infection due to its ability to recruit and activate phagocytic cells.