Lethal HSV-2 Challenge Research Articles

CCL28 Enhances HSV-2 gB-Specific Th1-Polarized Immune Responses against Lethal Vaginal Challenge in Mice.

Plasmid DNA (pDNA) represents a promising “genetic vaccine platform” capable of overcoming major histocompatibility complex barriers. We previously demonstrated that low-to-moderate doses of mucosae-associated epithelial chemokine (MEC or CCL28) as an immunomodulatory adjuvant can trigger effective and long-lasting systemic and mucosal HSV-2 gD-specific immune responses, whereas mice immunized with gD in combination with high-dose CCL28 showed toxicity and lost their immunoprotective effects after lethal HSV-2 challenge. The exact causes underlying high-dose, CCL28-induced lesions remain unknown. In an intramuscularly immunized mouse model, we investigated the immune-enhancement mechanisms of low-dose CCL28 as a molecular adjuvant combined with the relatively weak immunogen HSV-2 gB. Compared with the plasmid gB antigen group, we found that a low-dose of plasmid CCL28 (pCCL28) codelivered with pgB induced increased levels of gB-specific serum IgG and vaginal fluid IgA, serum neutralizing antibodies (NAb), Th1-polarized IgG2a, and cytokine IL-2 (>5-fold). Furthermore, low-dose pCCL28 codelivery with pgB enhanced CCL28/CCR10-axis responsive CCR10− plus CCR10+ B-cell (~1.2-fold) and DC pools (~4-fold) in the spleen, CCR10− plus CCR10+ T-cell pools (~2-fold) in mesenteric lymph nodes (MLNs), and the levels of IgA-ASCs in colorectal mucosal tissues, leading to an improved protective effect against a lethal dose of HSV-2 challenge. Findings in this study provide a basis for the development of CCL28-adjuvant vaccines against viral mucosal infections.

An HSV-2 nucleoside-modified mRNA genital herpes vaccine containing glycoproteins gC, gD, and gE protects mice against HSV-1 genital lesions and latent infection.

HSV-1 causes 50% of first-time genital herpes infections in resource-rich countries and affects 190 million people worldwide. A prophylactic herpes vaccine is needed to protect against genital infections by both HSV-1 and HSV-2. Previously our laboratory developed a trivalent vaccine that targets glycoproteins C, D, and E present on the HSV-2 virion. We reported that this vaccine protects animals from genital disease and recurrent virus shedding following lethal HSV-2 challenge. Importantly the vaccine also generates cross-reactive antibodies that neutralize HSV-1, suggesting it may provide protection against HSV-1 infection. Here we compared the efficacy of this vaccine delivered as protein or nucleoside-modified mRNA immunogens against vaginal HSV-1 infection in mice. Both the protein and mRNA vaccines protected mice from HSV-1 disease; however, the mRNA vaccine provided better protection as measured by lower vaginal virus titers post-infection. In a second experiment, we compared protection provided by the mRNA vaccine against intravaginal challenge with HSV-1 or HSV-2. Vaccinated mice were totally protected against death, genital disease and infection of dorsal root ganglia caused by both viruses, but somewhat better protected against vaginal titers after HSV-2 infection. Overall, in the two experiments, the mRNA vaccine prevented death and genital disease in 54/54 (100%) mice infected with HSV-1 and 20/20 (100%) with HSV-2, and prevented HSV DNA from reaching the dorsal root ganglia, the site of virus latency, in 29/30 (97%) mice infected with HSV-1 and 10/10 (100%) with HSV-2. We consider the HSV-2 trivalent mRNA vaccine to be a promising candidate for clinical trials for prevention of both HSV-1 and HSV-2 genital herpes.

IL-36γ Is a Key Regulator of Neutrophil Infiltration in the Vaginal Microenvironment and Limits Neuroinvasion in Genital HSV-2 Infection.

HSV-2 is a neurotropic virus that causes a persistent, lifelong infection that increases risk for other sexually transmitted infections. The vaginal epithelium is the first line of defense against HSV-2 and coordinates the immune response through the secretion of immune mediators, including the proinflammatory cytokine IL-36γ. Previously, we showed that IL-36γ treatment promoted transient polymorphonuclear cell infiltration to the vaginal cavity and protected against lethal HSV-2 challenge. In this report, we reveal that IL-36γ specifically induces transient neutrophil infiltration but does not impact monocyte and macrophage recruitment. Using IL-36γ-/- mice in a lethal HSV-2 challenge model, we show that neutrophil counts are significantly reduced at 1 and 2 d postinfection and that KC-mediated mature neutrophil recruitment is impaired in IL-36γ-/- mice. Additionally, IL-36γ-/- mice develop genital disease more rapidly, have significantly reduced survival time, and exhibit an increased incidence of hind limb paralysis that is linked to productive HSV-2 infection in the brain stem. IL-36γ-/- mice also exhibit a significant delay in clearance of the virus from the vaginal epithelium and a more rapid spread of HSV-2 to the spinal cord, bladder, and colon. We further show that the decreased survival time and increased virus spread observed in IL-36γ-/- mice are not neutrophil-dependent, suggesting that IL-36γ may function to limit HSV-2 spread in the nervous system. Ultimately, we demonstrate that IL-36γ is a key regulator of neutrophil recruitment in the vaginal microenvironment and may function to limit HSV-2 neuroinvasion.

IL-36γ regulates neutrophil infiltration and limits neuroinvasion in genital HSV-2 pathogenesis

Abstract Herpes simplex virus 2 is a neurotropic virus that causes a persistent, life-long infection that increases risk for other sexually transmitted infections. The vaginal epithelium is the first line of defense against HSV-2 and secretes immune mediators, including the pro-inflammatory cytokine IL-36γ, to coordinate the immune response. Previously, we showed that IL-36γ treatment promoted polymorphonuclear cell infiltration to the vaginal cavity and protected against lethal HSV-2 challenge. Herein, we extended these findings using flow cytometry to profile the cellular infiltrate. IL-36γ significantly (p < 0.0001) induced transient neutrophil infiltration, but did not impact monocyte or macrophage recruitment. Using IL-36γ−/− mice in a lethal HSV-2 challenge model, we show that neutrophils were significantly (p < 0.0001) depleted at 1- and 2-days post infection, and that mature neutrophil recruitment was impaired. In addition, IL-36γ−/− mice develop genital disease more rapidly (p < 0.0001), have significantly (p < 0.0001) reduced survival time, and display an increased incidence (p < 0.0001) of neurologic disease compared to wild type mice. IL-36γ−/− mice exhibited a significant (p < 0.05) delay in clearance of the virus from the vaginal epithelium, and analysis of virus spread to the spinal cord, bladder, and colon demonstrated that HSV-2 spread significantly (p < 0.05) more quickly in IL-36γ−/− mice. Further, we detected productive HSV-2 infection in the brainstem of IL-36γ−/− mice significantly (p < 0.0001) more frequently than in wild type mice. Ultimately, we demonstrate that IL-36γ is a key regulator of neutrophil recruitment in the vaginal microenvironment and may function to limit HSV-2 neuroinvasion.

The type I interferon receptor is not required for protection in the Chlamydia muridarum and HSV-2 murine super-infection model.

Chlamydia trachomatis/HSV-2 vaginal co-infections are seen clinically, suggesting that these sexually transmitted pathogens may interact. We previously established an intravaginal Chlamydia muridarum/HSV-2 super-infection model and observed that chlamydial pre-infection protects mice from a subsequent lethal HSV-2 challenge. However, the mechanism of protection remains unknown. The type I interferon, IFN-β, binds to the type I interferon receptor (IFNR), elicits a host cellular antiviral response and inhibits HSV replication in vitro and in vivo. Previous studies have demonstrated that C. muridarum infection stimulates genital tract (GT) IFN-β production; therefore, we hypothesized that chlamydial pre-infection protects mice from HSV-2 challenge via the IFN-β/IFNR-induced antiviral response. To test this prediction, we quantified IFN-β levels in vaginal swab samples. Detection of IFN-β in C. muridarum singly infected, but not in mock-infected animals, prompted the use of the super-infection model in IFNR knockout (IFNR−/−) mice. We observed that C. muridarum pre-infection reduces HSV-2-induced mortality by 40% in wild-type mice and by 60% IFNR−/− mice. Severity of HSV-2 disease symptoms and viral shedding was also similarly reduced by C. muridarum pre-infection. These data indicate that, while chlamydial infection induces GT production of IFN-β, type I IFN-induced antiviral responses are likely not required for the observed protective effect.

IL-15 Can Signal via IL-15Rα, JNK, and NF-κB To Drive RANTES Production by Myeloid Cells

IL-15 plays many important roles within the immune system. IL-15 signals in lymphocytes via trans presentation, where accessory cells such as macrophages and dendritic cells present IL-15 bound to IL-15Rα in trans to NK cells and CD8(+) memory T cells expressing IL-15/IL-2Rβ and common γ chain (γ(c)). Previously, we showed that the prophylactic delivery of IL-15 to Rag2(-/-)γ(c)(-/-) mice (mature T, B, and NK cell negative) afforded protection against a lethal HSV-2 challenge and metastasis of B16/F10 melanoma cells. In this study, we demonstrated that in vivo delivery of an adenoviral construct optimized for the secretion of human IL-15 to Rag2(-/-)γ(c)(-/-) mice resulted in significant increases in spleen size and cell number, leading us to hypothesize that IL-15 signals differently in myeloid immune cells compared with lymphocytes, for which IL-15/IL-2Rβ and γ(c) expression are essential. Furthermore, treatment with IL-15 induced RANTES production by Rag2(-/-)γ(c)(-/-) bone marrow cells, but the presence of γ(c) did not increase bone marrow cell sensitivity to IL-15. This IL-15-mediated RANTES production by Rag2(-/-)γ(c)(-/-) bone marrow cells occurred independently of the IL-15/IL-2Rβ and Jak/STAT pathways and instead required IL-15Rα signaling as well as activation of JNK and NF-κB. Importantly, we also showed that the trans presentation of IL-15 by IL-15Rα boosts IL-15-mediated IFN-γ production by NK cells but reduces IL-15-mediated RANTES production by Rag2(-/-)γ(c)(-/-) myeloid bone marrow cells. Our data clearly show that IL-15 signaling in NK cells is different from that of myeloid immune cells. Additional insights into IL-15 biology may lead to novel therapies aimed at bolstering targeted immune responses against cancer and infectious disease.

Native herpes simplex virus glycoprotein D vaccine: immunogenicity and protection in animal models

Mice, guinea pigs, and rhesus monkeys were immunized with immunoaffinity-purified native glycoprotein D (gD) derived from herpes simplex virus type 1 (HSV1). The native glycoprotein has evoked significant in vivo responses even at low doses. Thus, mice immunized with doses as low as 1 μg were significantly protected from the morbidity and mortality of lethal HSV2 challenge and from establishment of latent HSV2 infection. Protection was dose-related and correlated with prechallenge serum neutralizing antibody titres to HSV. Similarly, immunized guinea-pigs demonstrated significant reductions in the frequency, severity and duration of genital lesions induced by HSV2 vaginal challenge. In long term immunogenicity studies, immunized rhesus monkeys exhibited significant serum neutralizing antibody responses to both HSV1 and HSV2. In vitro stimulation of monkey peripheral blood leucocytes with purified gD resulted in a significant cellular proliferative response. The results obtained in these animal models with a gD subunit vaccine provide an appropriate foundation for the initiation of human studies.