Tissue-Resident-Memory CD8+ T Cells Bridge Innate Immune Responses in Neighboring Epithelial Cells to Control Human Genital Herpes.

Tissue-resident-memory T cells (TRM) populate the body's barrier surfaces, functioning as frontline responders against reencountered pathogens. Understanding of the mechanisms by which CD8TRM achieve effective immune protection remains incomplete in a naturally recurring human disease. Using laser capture microdissection and transcriptional profiling, we investigate the impact of CD8TRM on the tissue microenvironment in skin biopsies sequentially obtained from a clinical cohort of diverse disease expression during herpes simplex virus 2 (HSV-2) reactivation. Epithelial cells neighboring CD8TRM display elevated and widespread innate and cell-intrinsic antiviral signature expression, largely related to IFNG expression. Detailed evaluation via T-cell receptor reconstruction confirms that CD8TRM recognize viral-infected cells at the specific HSV-2 peptide/HLA level. The hierarchical pattern of core IFN-γ signature expression is well-conserved in normal human skin across various anatomic sites, while elevation of IFI16, TRIM 22, IFITM2, IFITM3, MX1, MX2, STAT1, IRF7, ISG15, IFI44, CXCL10 and CCL5 expression is associated with HSV-2-affected asymptomatic tissue. In primary human cells, IFN-γ pretreatment reduces gene transcription at the immediate-early stage of virus lifecycle, enhances IFI16 restriction of wild-type HSV-2 replication and renders favorable kinetics for host protection. Thus, the adaptive immune response through antigen-specific recognition instructs innate and cell-intrinsic antiviral machinery to control herpes reactivation, a reversal of the canonical thinking of innate activating adaptive immunity in primary infection. Communication from CD8TRM to surrounding epithelial cells to activate broad innate resistance might be critical in restraining various viral diseases.

Endogenous Retroviruses Provide Protection Against Vaginal HSV-2 Disease.

Endogenous retroviruses (ERVs) are genomic sequences that originated from retroviruses and are present in most eukaryotic genomes. Both beneficial and detrimental functions are attributed to ERVs, but whether ERVs contribute to antiviral immunity is not well understood. Here, we used herpes simplex virus type 2 (HSV-2) infection as a model and found that Toll-like receptor 7 (Tlr7-/-) deficient mice that have high systemic levels of infectious ERVs are protected from intravaginal HSV-2 infection and disease, compared to wildtype C57BL/6 mice. We deleted the endogenous ecotropic murine leukemia virus (Emv2) locus on the Tlr7-/- background (Emv2-/-Tlr7-/-) and found that Emv2-/-Tlr7-/- mice lose protection against HSV-2 infection. Intravaginal application of purified ERVs from Tlr7-/- mice prior to HSV-2 infection delays disease in both wildtype and highly susceptible interferon-alpha receptor-deficient (Ifnar1-/-) mice. However, intravaginal ERV treatment did not protect Emv2-/-Tlr7-/- mice from HSV-2 disease, suggesting that the protective mechanism mediated by exogenous ERV treatment may differ from that of constitutively and systemically expressed ERVs in Tlr7-/- mice. We did not observe enhanced type I interferon (IFN-I) signaling in the vaginal tissues from Tlr7-/- mice, and instead found enrichment in genes associated with extracellular matrix organization. Together, our results revealed that constitutive and/or systemic expression of ERVs protect mice against vaginal HSV-2 infection and delay disease.

Glutamine supplementation suppresses herpes simplex virus reactivation.

Chronic viral infections are difficult to treat, and new approaches are needed, particularly those aimed at reducing reactivation by enhancing immune responses. Herpes simplex virus (HSV) establishes latency and reactivates frequently, and breakthrough reactivation can occur despite suppressive antiviral therapy. Virus-specific T cells are important to control HSV, and proliferation of activated T cells requires increased metabolism of glutamine. Here, we found that supplementation with oral glutamine reduced virus reactivation in latently HSV-1-infected mice and HSV-2-infected guinea pigs. Transcriptome analysis of trigeminal ganglia from latently HSV-1-infected, glutamine-treated WT mice showed upregulation of several IFN-γ-inducible genes. In contrast to WT mice, supplemental glutamine was ineffective in reducing the rate of HSV-1 reactivation in latently HSV-1-infected IFN-γ-KO mice. Mice treated with glutamine also had higher numbers of HSV-specific IFN-γ-producing CD8 T cells in latently infected ganglia. Thus, glutamine may enhance the IFN-γ-associated immune response and reduce the rate of reactivation of latent virus infection.

Effects of a traditional Chinese medicine, Longdanxiegan formula granule, on Toll-like receptor pathway in female guinea pigs with recurrent genital herpes.

OBJECTIVE: The aim of the present study was to investigate the effects of Longdanxiegan formula granule (LDXGFG), a Chinese traditional medicine on Toll-like receptor (TLR) pathway in recurrent genital herpes. MATERIALS AND METHODS: An experimental recurrent genital herpes model was constructed using herpes guinea pig model. The effect of LDXGFG on expression levels of TLR pathway genes were detected using real-time polymerase chain reaction. Furthermore, the dendritic cells and Langerhans cells were isolated and the TLR pathway genes of these cells were assayed after LDXGFG treatment. RESULTS: The result suggested two different expression patterns of TLR pathway genes in genital herpes and recurrent genital herpes, including upregulated genes and downregulated genes. TLR1, TLR4, TLR6, TLR7, TLR8, TLR9, and TLR10 showed a significant decrease while, TLR2, TLR3, and TLR5 increased in genital herpes and recurrent genital herpes guinea pigs. Meanwhile, the downregulated genes in genital herpes and recurrent genital herpes were stimulated by LDXGFG. By contrast, the upregulated genes decreased significantly after LDXGFG treatment. In both dendritic cells and Langerhans cells, the TLR pathway genes exhibited same pattern: the LDXGFG corrected the abnormal expression of TLR pathway genes. CONCLUSION: The present results suggest that LDXGFG is an alternative, inexpensive, and lasting-effect medicine for herpes simplex virus 2 infection.

High Rate of ß-Globin DNA Detection Validates Self-Sampling in Herpes Simplex Virus Shedding Studies.

BACKGROUND: Self-sampling is a convenient, feasible, and acceptable way of collecting genital specimens, but the veracity of reported self-collection is difficult to verify. We investigated whether a host gene, ß-globin, can be used to confirm adequacy of self-collected mucosal and skin genital specimens in studies of genital herpes simplex virus type 2 (HSV-2) infection. METHODS: Herpes simplex virus type 2-seropositive adults self-collected daily anogenital and oral swabs. Mucosal samples were tested for HSV DNA using a real-time quantitative polymerase chain reaction assay. A real-time Taqman polymerase chain reaction detecting the ß-globin gene was used to quantify host cells. RESULTS: One hundred twelve participants collected 5559 genital and 2002 oral swabs. Sixty (54%) were women, 65% were HSV-2 seropositive, and 35% were HSV-1 and HSV-2 seropositive by Western blot. ß-globin DNA was detected in 99% and 93% of swabs obtained from women and men, respectively. The quantity of ß-globin DNA detected was significantly higher when HSV was present in genital swabs in women (0.1 log10 copies/mL; P = 0.001) and in men (0.6 log10 copies/mL; P < 0.001), but not in oral swabs in women (0.2 log10 copies/mL; P = 0.08) or men (0.0 log10 copies/mL; P = 0.70). CONCLUSIONS: Human ß-globin DNA detection rate was high, and the quantity obtained significantly increased with genital, but not oral HSV shedding. The high rate of ß-globin DNA detection is consistent with high adherence to study procedures in longitudinal studies of genital herpes shedding.

Interferon Lambda 4 Genotype Is Not Associated with Recurrence of Oral or Genital Herpes.

IFNL4-ΔG/TT (rs368234815) genotype is associated with hepatitis C virus clearance and may play a role in other infections. IFN-λ4 protein is generated only in individuals who carry the IFNL4-ΔG allele. The IFNL4 rs12979860-T allele, which is in strong linkage disequilibrium with IFNL4-ΔG, was recently reported to be associated with more frequent and severe oral herpes episodes. We investigated the association of IFNL4-ΔG/TT with herpes simplex virus (HSV)-related outcomes among 2,192 African American and European American participants in the Women's Interagency HIV Study (WIHS). WIHS is a prospective cohort study of human immunodeficiency virus (HIV)-infected and at-risk women that began in 1994. This report includes follow-up through 2013. Available data included: HSV-1 and HSV-2 antibodies at study entry; bi-annually ascertained episodes of (self-reported) oral herpes, (self-reported) genital sores and (clinician-observed) genital ulcers; HSV-2 DNA in cervicovaginal lavage (CVL) specimens. IFNL4-ΔG/TT genotyping was determined by TaqMan. We compared women with IFNL4-ΔG/ΔG or IFNL4-TT/ΔG genotypes (i.e., IFNL4-ΔG carriers) to those with the IFNL4-TT/TT genotype, adjusting for age, race and HIV status. For outcomes with repeated measurements, the adjusted odds ratio (aOR), 95% confidence interval [CI] and p-value were determined using a generalized estimating equations approach. Median participant age at enrollment was 36 years; 81% were African American, 74% were HIV-infected. Among 1,431 participants tested for antibodies, 72.8% were positive for HSV-1 and 79.0% were positive for HSV-2. We observed no association between IFNL4-ΔG/TT genotype and any outcome: HSV-1 or HSV-2 antibody prevalence (p>0.1, all comparisons); oral herpes (aOR, 1.2; p = 0.35); genital sores (aOR, 1.0; p = 0.71); genital ulcers (aOR, 1.1; p = 0.53); detectable HSV-2 DNA in CVL (N = 322; aOR, 0.71; p = 0.49); HSV-2 DNA level (p = 0.68). In this large prospective study, IFNL4-ΔG/TT genotype was not associated with HSV-related outcomes, including episodes of oral or genital herpes.

Genetic Diversity within Alphaherpesviruses: Characterization of a Novel Variant of Herpes Simplex Virus 2.

UNLABELLED: Very low levels of variability have been reported for the herpes simplex virus 2 (HSV-2) genome. We recently described a new genetic variant of HSV-2 (HSV-2v) characterized by a much higher degree of variability for the UL30 gene (DNA polymerase) than observed for the HG52 reference strain. Retrospective screening of 505 clinical isolates of HSV-2 by a specific real-time PCR assay targeting the UL30 gene led to the identification of 13 additional HSV-2v isolates, resulting in an overall prevalence of 2.8%. Phylogenetic analyses on the basis of microsatellite markers and gene sequences showed clear differences between HSV-2v and classical HSV-2. Thirteen of the 14 patients infected with HSV-2v originated from West or Central Africa, and 9 of these patients were coinfected with HIV. These results raise questions about the origin of this new virus. Preliminary results suggest that HSV-2v may have acquired genomic segments from chimpanzee alphaherpesvirus (ChHV) by recombination. IMPORTANCE: This article deals with the highly topical question of the origin of this new HSV-2 variant identified in patients with HIV coinfection originating mostly from West or Central Africa. HSV-2v clearly differed from classical HSV-2 isolates in phylogenetic analyses and may be linked to simian ChHV. This new HSV-2 variant highlights the possible occurrence of recombination between human and simian herpesviruses under natural conditions, potentially presenting greater challenges for the future.

The Vaginal Acquisition and Dissemination of HIV-1 Infection in a Novel Transgenic Mouse Model Is Facilitated by Coinfection with Herpes Simplex Virus 2 and Is Inhibited by Microbicide Treatment.

UNLABELLED: Epidemiological studies have demonstrated that herpes simplex virus 2 (HSV-2) infection significantly increases the risk of HIV-1 acquisition, thereby contributing to the expanding HIV-1 epidemic. To investigate whether HSV-2 infection directly facilitates mucosal HIV-1 acquisition, we used our transgenic hCD4/R5/cT1 mouse model which circumvents major entry and transcription blocks preventing murine HIV-1 infection by targeting transgenic expression of human CD4, CCR5, and cyclin T1 genes to CD4(+) T cells and myeloid-committed cells. Productive infection of mucosal leukocytes, predominantly CD4(+) T cells, was detected in all hCD4/R5/cT1 mice intravaginally challenged with an HIV-1 infectious molecular clone, HIV-Du151.2env-NLuc, which expresses an env gene (C.Du151.2) cloned from an acute heterosexually infected woman and a NanoLuc luciferase reporter gene. Lower genital tract HIV-1 infection after HIV-Du151.2env-NLuc intravaginal challenge was increased ~4-fold in hCD4/R5/cT1 mice coinfected with HSV-2. Furthermore, HIV-1 dissemination to draining lymph nodes was detected only in HSV-2-coinfected mice. HSV-2 infection stimulated local infiltration and activation of CD4(+) T cells and dendritic cells, likely contributing to the enhanced HIV-1 infection and dissemination in HSV-2-coinfected mice. We then used this model to demonstrate that a novel gel containing tenofovir disoproxil fumarate (TDF), the more potent prodrug of tenofovir (TFV), but not the TFV microbicide gel utilized in the recent CAPRISA 004, VOICE (Vaginal and Oral Interventions to Control the Epidemic), and FACTS 001 clinical trials, was effective as preexposure prophylaxis (PrEP) to completely prevent vaginal HIV-1 infection in almost half of HSV-2-coinfected mice. These results also support utilization of hCD4/R5/cT1 mice as a highly reproducible immunocompetent preclinical model to evaluate HIV-1 acquisition across the female genital tract. IMPORTANCE: Multiple epidemiological studies have reported that genital herpes simplex virus 2 (HSV-2) infection increases the risk of HIV-1 sexual acquisition by severalfold. Understanding the underlying mechanisms by which HSV-2 facilitates HIV-1 infection and optimizing the efficacy of therapies to inhibit HIV-1 infection during HSV-2 coinfection should contribute to reducing HIV-1 transmission. Using our novel transgenic hCD4/R5/cT1 mouse model infectible with HIV-1, we demonstrated that HSV-2 infection enhances vaginal transmission and dissemination of HIV-1 infection while stimulating recruitment and activation of CD4(+) T cells and dendritic cells in the lower genital tract. HIV acquisition by hCD4/R5/cT1 mice vaginally coinfected with HSV-2 could be completely prevented in almost half the mice by preexposure prophylaxis (PrEP) with a novel gel containing tenofovir disoproxil fumarate (TDF), the tenofovir prodrug, but not with the tenofovir microbicide gel utilized in CAPRISA-004, VOICE, and FACTS-001 clinical trials. The hCD4/R5/cT1 mice represent a new preclinical mouse model to evaluate vaginal HIV-1 acquisition.

Herpes simplex virus type 2-infected dendritic cells produce TNF-α, which enhances CCR5 expression and stimulates HIV production from adjacent infected cells.

Prior HSV-2 infection enhances the acquisition of HIV-1 >3-fold. In genital herpes lesions, the superficial layers of stratified squamous epithelium are disrupted, allowing easier access of HIV-1 to Langerhans cells (LC) in the epidermis and perhaps even dendritic cells (DCs) in the outer dermis, as well as to lesion infiltrating activated T lymphocytes and macrophages. Therefore, we examined the effects of coinfection with HIV-1 and HSV-2 on monocyte-derived DCs (MDDC). With simultaneous coinfection, HSV-2 significantly stimulated HIV-1 DNA production 5-fold compared with HIV-1 infection alone. Because <1% of cells were dually infected, this was a field effect. Virus-stripped supernatants from HSV-2-infected MDDCs were shown to enhance HIV-1 infection, as measured by HIV-1-DNA and p24 Ag in MDDCs. Furthermore these supernatants markedly stimulated CCR5 expression on both MDDCs and LCs. TNF-α was by far the most prominent cytokine in the supernatant and also within HSV-2-infected MDDCs. HSV-2 infection of isolated immature epidermal LCs, but not keratinocytes, also produced TNF-α (and low levels of IFN-ß). Neutralizing Ab to TNF-α and its receptor, TNF-R1, on MDDCs markedly inhibited the CCR5-stimulating effect of the supernatant. Therefore, these results suggest that HSV-2 infection of DCs in the skin during primary or recurrent genital herpes may enhance HIV-1 infection of adjacent DCs, thus contributing to acquisition of HIV-1 through herpetic lesions.

Modulation of CD112 by the alphaherpesvirus gD protein suppresses DNAM-1-dependent NK cell-mediated lysis of infected cells.

Natural killer (NK) cells are key players in the innate response to viruses, including herpesviruses. In particular, the variety of viral strategies to modulate the recognition of certain herpesviruses witnesses the importance of NK cells in the control of this group of viruses. Still, NK evasion strategies have remained largely elusive for the largest herpesvirus subfamily, the alphaherpesviruses. Here, we report that the gD glycoprotein of the alphaherpesviruses pseudorabies virus (PRV) and herpes simplex virus 2 (HSV-2) displays previously uncharacterized immune evasion properties toward NK cells. Expression of gD during infection or transfection led to degradation and consequent down-regulation of CD112, a ligand for the activating NK receptor DNAX accessory molecule 1 (DNAM-1). CD112 downregulation resulted in a reduced ability of DNAM-1 to bind to the surface of both virus-infected and gD-transfected cells. Consequently, expression of gD suppressed NK cell degranulation and NK cell-mediated lysis of PRV- or HSV-2-infected cells. These data identify an alphaherpesvirus evasion strategy from NK cells and point out that interactions between viral envelope proteins and host cell receptors can have biological consequences that stretch beyond virus entry.

Identification of novel virus-specific antigens by CD4⁺ and CD8⁺ T cells from asymptomatic HSV-2 seropositive and seronegative donors.

Reactivation of latent herpes simplex virus 2 (HSV-2) infections can be characterized by episodic recurrent genital lesions and/or viral shedding. We hypothesize that infected (HSV-2(pos)) asymptomatic individuals have acquired T cell responses to specific HSV-2 antigen(s) that may be an important factor in controlling their recurrent disease symptoms. Our proteomic screening technology, ATLAS, was used to characterize the antigenic repertoire of T cell responses in infected (HSV-2(pos)) and virus-exposed seronegative (HSV-2(neg)) subjects. T cell responses, determined by IFN-γ secretion, were generated to gL, UL2, UL11, UL21, ICP4, ICP0, ICP47 and UL40 with greater magnitude and/or frequency among cohorts of exposed HSV-2(neg) or asymptomatic HSV-2(pos) individuals, compared to symptomatic recurrent HSV-2(pos) subjects. T cell antigens recognized preferentially among individuals who are resistant to infection or who are infected and have mild or no clinical disease may provide new targets for the design of vaccines aimed at treating and/or preventing HSV-2 infection.

CD18 deficiency evolving to megakaryocytic (M7) acute myeloid leukemia: case report.

Leukocyte adhesion deficiency type 1 (LAD 1 - CD18 deficiency) is a rare disease characterized by disturbance of phagocyte function associated with less severe cellular and humoral dysfunction. The main features are bacterial and fungal infections predominantly in the skin and mucosal surfaces, impaired wound healing and delayed umbilical cord separation. The infections are indolent, necrotic and recurrent. In contrast to the striking difficulties in defense against bacterial and fungal microorganisms, LAD 1 patients do not exhibit susceptibility to viral infections and neoplasias. The severity of clinical manifestations is directly related to the degree of CD18 deficiency. Here, a 20 year-old female presenting a partial CD18 deficiency that developed a megakaryocytic (M7) acute myeloid leukemia is described for the first time. The clinical features of the patient included relapsing oral thrush due to Candida, cutaneous infections and upper and lower respiratory tract infections, followed by a locally severe necrotic genital herpetic lesion. The patient's clinical features improved for a period of approximately two years, followed by severe bacterial infections. At that time, the investigation showed a megakaryocytic acute myeloid leukemia, treated with MEC without clinical improvement. The highly aggressive evolution of the leukemia in this patient suggests that adhesion molecules could be involved in the protection against the spread of neoplastic cells.

Impact of asymptomatic herpes simplex virus type 2 infection on mucosal homing and immune cell subsets in the blood and female genital tract.

HSV-2 infection is common and generally asymptomatic, but it is associated with increased HIV susceptibility and disease progression. This may relate to herpes-mediated changes in genital and systemic immunology. Cervical cytobrushes and blood were collected from HIV-uninfected African/Caribbean women in Toronto, and immune cell subsets were enumerated blindly by flow cytometry. Immune differences between groups were assessed by univariate analysis and confirmed using a multivariate model. Study participants consisted of 46 women, of whom 54% were infected with HSV-2. T cell activation and expression of the mucosal homing integrin α4ß7 (19.60 versus 8.76%; p < 0.001) were increased in the blood of HSV-2-infected women. Furthermore, expression of α4ß7 on blood T cells correlated with increased numbers of activated (coexpressing CD38/HLA-DR; p = 0.004) and CCR5(+) (p = 0.005) cervical CD4(+) T cells. HSV-2-infected women exhibited an increase in the number of cervical CD4(+) T cells (715 versus 262 cells/cytobrush; p = 0.016), as well as an increase in the number and proportion of cervical CD4(+) T cells that expressed CCR5(+) (406 versus 131 cells, p = 0.001; and 50.70 versus 34.90%, p = 0.004) and were activated (112 versus 13 cells, p < 0.001; and 9.84 versus 4.86%, p = 0.009). Mannose receptor expression also was increased on cervical dendritic cell subsets. In conclusion, asymptomatic HSV-2 infection was associated with significant systemic and genital immune changes, including increased immune activation and systemic α4ß7 expression; correlation of the latter with highly HIV-susceptible CD4(+) T cell subsets in the cervix may provide a mechanism for the increased HIV susceptibility observed in asymptomatic HSV-2-infected women.

Silencing sexually transmitted infections: topical siRNA-based interventions for the prevention of HIV and HSV.

The global impact of sexually transmitted infections (STIs) is significant. The sexual transmission of viruses such as herpes simplex virus type-2 (HSV-2) and the human immunodeficiency virus type-1 (HIV-1), has been especially difficult to control. To date, no effective vaccines have been developed to prevent the transmission of these STIs. Although antiretroviral drugs have been remarkably successful in treating the symptoms associated with these viral infections, the feasibility of their widespread use for prevention purposes may be more limited. Microbicides might provide an attractive alternative option to reduce their spread. In particular, topically applied small inhibitory RNAs (siRNAs) have been shown to not only block transmission of viral STIs to mucosal tissues both in vitro and in vivo, but also confer durable knockdown of target gene expression, thereby circumventing the need to apply a microbicide around the time of sexual encounter, when compliance is mostly difficult. Despite numerous clinical trials currently testing the efficacy of siRNA-based therapeutics, they have yet to be approved for use in the treatment of viral STIs. While several obstacles to their successful implementation in the clinic still exist, promising preclinical studies suggest that siRNAs are a viable modality for the future prevention and treatment of HSV and HIV.

Fas/FasL pathway participates in resolution of mucosal inflammatory response early during HSV-2 infection.

Apoptotic cell death is critical for maintaining integrity of the epithelia as well as for removal of the virus infected cells. We assessed the role of Fas/FasL-dependent pathway in apoptosis of genital epithelium during HSV-2 infection using a murine model of HSV-2 infection applied to C57BL6, MRL-Fas(lpr)/J (Fas-/-) and C3-Fasl(gld)/J (FasL-/-) mice and an in vitro model of HSV-2 infection in monocyte RAW 264.7 and keratinocyte 291.03C cell cultures and peritoneal macrophages. In contrast to keratinocyte in vitro cultures, HSV-2 infection of the monocytic cell cultures led to early induction of apoptosis. HSV-2 infection of peritoneal macrophages isolated from Fas- and FasL-deficient mice showed decreased activation of apoptosis, which could be further blocked by caspase-9 inhibitor. Infection of Fas and FasL-deficient mice increased the percentage of apoptotic cells and activation of caspase-9 in the vaginal tissue in comparison to C57BL6 wild type strain. Furthermore, Fas and FasL-deficient mice showed increased infiltration of neutrophiles in the vaginal mucosal epithelium at 3 and 7 day of infection in contrast to HSV-2 infected wild-type mice. Our results show that while the Fas/FasL pathway during HSV-2 infection of the vaginal epithelium plays an important role in controlling early local inflammatory response, mitochondrial apoptotic pathway also becomes activated by the inflammatory reaction.

Plasmacytoid dendritic cells contribute to systemic but not local antiviral responses to HSV infections.

Plasmacytoid dendritic cells (pDC) produce type I interferons (IFN-I) and proinflammatory cytokines in response to viruses; however, their contribution to antiviral immunity in vivo is unclear. In this study, we investigated the impact of pDC depletion on local and systemic antiviral responses to herpes simplex virus (HSV) infections using CLEC4C-DTR transgenic mice. We found that pDC do not appear to influence viral burden or survival after vaginal HSV-2 infection, nor do they seem to contribute to virus-specific CD8 T cell responses following subcutaneous HSV-1 infection. In contrast, pDC were important for early IFN-I production, proinflammatory cytokine production, NK cell activation and CD8 T cell responses during systemic HSV-2 and HSV-1 infections. Our data also indicate that unlike pDC, TLR3-expressing cells are important for promoting antiviral responses to HSV-1 regardless of the route of virus administration.

HSV-2 regulates monocyte inflammatory response via the Fas/FasL pathway.

Monocytic cells represent important cellular elements of the innate and adaptive immune responses in viral infections. We assessed the role of Fas/FasL in promoting monocyte apoptosis during HSV-2 infection by using an in vitro model based on the murine RAW 264.7 monocytic cell line and an in vivo murine model of HSV-2 infection applied to C57BL6, MRL-Fas(lpr)/J (Fas-/-) and C3-Fasl(gld)/J (FasL-/-) mice. HSV-2 infection of the monocytic cell line led to early induction of apoptosis, with no protective expression of anti-apoptotic Bcl-2. HSV-2 infected monocytes up-regulated Fas and FasL expression early during in vitro infection but were susceptible to Fas induced apoptosis. The vaginal monocytes in the HSV-2 murine model of infection up-regulated FasL expression and were susceptible to Fas induced apoptosis. HSV-2 infection of Fas and FasL- deficient mice led to decreased apoptosis of monocytes and impaired recruitment of NK, CD4+ and CD8+ T cells within the infection sites. The vaginal lavages of HSV-2 infected Fas and FasL- deficient showed decreased production of CXCL9, CXCL10 and TNF-α in comparison to HSV-2 infected wild-type mice strain. The decreased recruitment of immune competent cells was accompanied by delayed virus clearance from the infected tissue. Triggering of the Fas receptor on HSV-2 infected monocytes in vitro up-regulated the expression of CXCL9 chemokines and the cytokine TNF-α. Our study provides novel insights on the role of Fas/FasL pathway not only in apoptosis of monocytes but also in regulating local immune response by monocytes during HSV-2 infection.

Interferon-ε protects the female reproductive tract from viral and bacterial infection.

The innate immune system senses pathogens through pattern-recognition receptors (PRRs) that signal to induce effector cytokines, such as type I interferons (IFNs). We characterized IFN-ε as a type I IFN because it signaled via the Ifnar1 and Ifnar2 receptors to induce IFN-regulated genes. In contrast to other type I IFNs, IFN-ε was not induced by known PRR pathways; instead, IFN-ε was constitutively expressed by epithelial cells of the female reproductive tract (FRT) and was hormonally regulated. Ifn-ε-deficient mice had increased susceptibility to infection of the FRT by the common sexually transmitted infections (STIs) herpes simplex virus 2 and Chlamydia muridarum. Thus, IFN-ε is a potent antipathogen and immunoregulatory cytokine that may be important in combating STIs that represent a major global health and socioeconomic burden.

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.

Pathological effect of IL-17A-producing TCRγδ(+) T cells in mouse genital mucosa against HSV-2 infection.

Interleukin (IL)-17A is a cytokine that plays an important role in infectious, autoimmune, and inflammatory diseases. In this study, we found that TCRγδ(+)CD4(-)CD8(-) T cells, but not TCRαß(+)CD4(+) T cells, are the primary producers of IL-17A in the genital tract of female mice in the steady-state condition. High mRNA levels of IL-17A and RORγt were determined in TCRγδ(+) T cells isolated from mouse genital tract but lacked detectable expression of IFNγ, T-bet, and FoxP3. IL-17A production by genital TCRγδ(+) T cells was maintained after intravaginal vaccination with cholera toxin or avirulent herpes simplex virus type (HSV)-2 186 syn ΔTK strain. Of note, the deaths of IL-17A(-/-) mice were significantly delayed after intravaginal HSV-2 infection compared with wild-type mice. Further, genital TCRγδ(+) T cells continued to produce comparable amounts of IL-17A after antibiotic treatment. These results imply that genital IL-17A-producing TCRγδ(+) T cells constitutively exist at steady state and that they play a pathogenic effect against HSV-2 infection and are not affected by microflora, unlike conventional Th17 cells.