VEGF-A expression by HSV-1–infected cells drives corneal lymphangiogenesis

Herpes simplex virus 1 (HSV-1) most commonly causes recrudescent labial ulcers; however, it is also the leading cause of infectious blindness in developed countries. Previous research in animal models has demonstrated that the severity of HSV-1 ocular disease is influenced by three main factors: host innate immunity, host immune response, and viral strain. We have previously shown that mixed infection with two avirulent HSV-1 strains (OD4 and CJ994) results in recombinants with a wide range of ocular disease phenotype severity. Recently, we developed a quantitative trait locus (QTL)-based computational approach (vQTLmap) to identify viral single nucleotide polymorphisms (SNPs) predicted to influence the severity of the ocular disease phenotypes. We have now applied vQTLmap to identify HSV-1 SNPs associated with corneal neovascularization and mean peak percentage weight loss (MPWL) using 65 HSV-1 OD4-CJ994 recombinants. The vQTLmap analysis using Random Forest for neovascularization identified phenotypically meaningful nonsynonymous SNPs in the ICP4, UL41 (VHS), UL42, UL46 (VP11/ 12), UL47 (VP13/14), UL48 (VP22), US3, US4 (gG), US6 (gD), and US7 (gI) coding regions. The ICP4 gene was previously identified as a corneal neovascularization determinant, validating the vQTLmap method. Further analysis detected an epistatic interaction for neovascularization between a segment of the unique long (UL) region and a segment of the inverted repeat short (IRS)/unique short (US) region. Ridge regression was used to identify MPWL-associated nonsynonymous SNPs in the UL1 (gL), UL2, UL4, UL49 (VP22), UL50, and ICP4 coding regions. The data provide additional insights into virulence gene and epistatic interaction discovery in HSV-1. IMPORTANCEHerpes simplex virus 1 (HSV-1) typically causes recurrent cold sores; however, it is also the leading source of infectious blindness in developed countries. Corneal neovascularization is critical for the progression of blinding ocular disease, and weight loss is a measure of infection severity. Previous HSV-1 animal virulence studies have shown that the severity of ocular disease is partially due to the viral strain. In the current study, we used a recently described computational quantitative trait locus (QTL) approach in conjunction with 65 HSV-1 recombinants to identify viral single nucleotide polymorphisms (SNPs) involved in neovascularization and weight loss. Neovascularization SNPs were identified in the ICP4, VHS, UL42, VP11/12, VP13/14, VP22, gG, US3, gD, and gI genes. Further analysis revealed an epistatic interaction between the UL and US regions. MPWL-associated SNPs were detected in the UL1 (gL), UL2, UL4, VP22, UL50, and ICP4 genes. This approach will facilitate future HSV virulence studies. Herpes simplex virus 1 (HSV-1) is most commonly responsible for recurrent vesicular lesions of the oral mucosa; however, HSV-1 is increasingly found in genital infections, and it is the leading cause of infectious blindness and sporadic encephalitis in developed countries (1-4). The ...

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confidence: 99%

Mapping Murine Corneal Neovascularization and Weight Loss Virulence Determinants in the Herpes Simplex Virus 1 Genome and the Detection of an Epistatic Interaction between the UL and IRS/US Regions

Lee

Kolb

Larsen

et al. 2016

“…Recent studies have investigated the mechanisms by which HSV-1 induces lymphangiogenesis in the cornea during early acute infection (10,11). Following HSV-1 infection of corneal epithelial cells, the HSV-1-encoded transcription factor ICP4 binds the promoter region of VEGFA and drives expression of the proangiogenic growth factor (11).…”

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confidence: 99%

Tumor Necrosis Factor Alpha and Interleukin-6 Facilitate Corneal Lymphangiogenesis in Response to Herpes Simplex Virus 1 Infection

Bryant-Hudson

Gurung

Zheng

et al. 2014

Herpes simplex virus 1 (HSV-1) is a common human pathogen of clinical significance due to its association with vision impairment and encephalitis. In a mouse model of ocular neovascularization, we have previously shown that HSV-1 elicits the genesis of lymphatic vessels into the cornea proper through epithelial cell expression of vascular endothelial growth factor A (VEGFA) dependent upon expression of VEGFR2 during acute infection. We hypothesized that other factors may be involved in lymphangiogenesis, with proinflammatory cytokines as the leading candidates. IMPORTANCEWe have identified at least two proinflammatory cytokines expressed locally that are involved in the genesis of lymphatic vessels in the normally avascular cornea in response to HSV-1 infection. This finding provides the basis to target IL-6 and TNF-␣ as additional proangiogenic factors in the cornea during the development of herpetic stromal keratitis as a means to alleviate further neovascularization and tissue pathology associated with the host immune response to the pathogen.

“…Phylogenetic differences among virulence determinants in different HSV-1 strains are associated with various degrees of corneal neovascularization (71). In particular, the HSV-1 ICP4 protein is a major factor responsible for inducing corneal lymphangiogenesis by driving vascular endothelial growth factor (VEGF) expression in infected corneal epithelial cells (72). As discussed previously, the HSV-1 KOS strain does not induce the same extent of corneal pathology as other strains often used for laboratory research (38)(39)(40).…”

Section: Discussionmentioning

confidence: 96%

“…1E). Corneas were prepared for histological analysis of corneal innervation and vascularity as previously described (44,72). Immunolabeled corneal flat mounts were imaged using an Olympus FV1200 confocal microscope.…”

Section: Methodsmentioning

confidence: 99%

Impact of Type I Interferon on the Safety and Immunogenicity of an Experimental Live-Attenuated Herpes Simplex Virus 1 Vaccine in Mice

Royer

Carr

Chucair-Elliott

et al. 2017

Viral fitness dictates virulence and capacity to evade host immune defenses. Understanding the biological underpinnings of such features is essential for rational vaccine development. We have previously shown that the live-attenuated herpes simplex virus 1 (HSV-1) mutant lacking the nuclear localization signal (NLS) on the ICP0 gene (0ΔNLS) is sensitive to inhibition by interferon beta (IFN-␤) in vitro and functions as a highly efficacious experimental vaccine. Here, we characterize the host immune response and in vivo pathogenesis of HSV-1 0ΔNLS relative to its fully virulent parental strain in C57BL/6 mice. Additionally, we explore the role of type 1 interferon (IFN-␣/␤) signaling on virulence and immunogenicity of HSV-1 0ΔNLS and uncover a probable sex bias in the induction of IFN-␣/␤ in the cornea during HSV-1 infection. Our data show that HSV-1 0ΔNLS lacks neurovirulence even in highly immunocompromised mice lacking the IFN-␣/␤ receptor. These studies support the translational viability of the HSV-1 0ΔNLS vaccine strain by demonstrating that, while it is comparable to a virulent parental strain in terms of immunogenicity, HSV-1 0ΔNLS does not induce significant tissue pathology.IMPORTANCE HSV-1 is a common human pathogen associated with a variety of clinical presentations ranging in severity from periodic "cold sores" to lethal encephalitis. Despite the consistent failures of HSV subunit vaccines in clinical trials spanning the past 28 years, opposition to live-attenuated HSV vaccines predicated on unfounded safety concerns currently limits their widespread acceptance. Here, we demonstrate that a live-attenuated HSV-1 vaccine has great translational potential.KEYWORDS HSV-1, T cells, antibody, cornea, mouse, neovascularization S trategies for vaccine development have transitioned largely from empirical to so-called "next-generation" or rational approaches during the past 2 decades, a shift largely driven by technological advances and a better understanding of how innate immunity influences the generation of adaptive protection (1, 2). Despite these breakthroughs, the average person still acquires multiple herpesvirus infections during childhood (3). A licensed vaccine, however, exists only for varicella-zoster virus (VZV) (4). The live-attenuated Oka vaccine for VZV is generally well tolerated and has significantly reduced the incidence of VZV infection, morbidity, and mortality in the United States (5, 6). Furthermore, epidemiologic studies indicate that acquisition of herpes simplex virus 1 (HSV-1) has shifted toward early to late adolescence in recent decades within the United States, potentially creating an opportunity to introduce an effective prophylactic HSV-1 vaccine into the childhood vaccine regimen (7). HSV vaccines have been tested in multiple clinical trials, but these studies have focused on protein subunit vaccines