Herpes simplex virus type 1 DNA in human corneas: what are the virological and clinical implications?

Microbiome-Mediated Upregulation of MicroRNA-146a in Sporadic Alzheimer's Disease

The first indication of a potential mechanistic link between the pathobiology of the human gastrointestinal (GI)-tract microbiome and its contribution to the pathogenetic mechanisms of sporadic Alzheimer's disease (AD) came a scant 4 years ago (1). Ongoing research continues to strengthen the hypothesis that neurotoxic microbial-derived components of the GI tract microbiome can cross aging GI tract and blood-brain barriers and contribute to progressive proinflammatory neurodegeneration, as exemplified by the AD-process. Of central interest in these recent investigations are the pathological roles played by human GI tract resident Gram-negative anaerobic bacteria and neurotropic viruses-two prominent divisions of GI tract microbiome-derived microbiota-which harbor considerable pathogenic potential. It is noteworthy that the first two well-studied microbiota-the GI tract abundant Gram-negative bacteria Bacteroides fragilis and the neurotropic herpes simplex virus-1 both share a final common pathway of NF-κB (p50/p65) activation and microRNA-146a induction with ensuing pathogenic stimulation of innate-immune and neuroinflammatory pathways. These appear to strongly contribute to the inflammation-mediated amyloidogenic neuropathology of AD. This communication: (i) will review recent research contributions that have expanded our understanding of the nature of the translocation of microbiome-derived neurotoxins-across biophysiological barriers; (ii) will assess multiple-recent investigations of the induction of the proinflammatory pathogenic microRNA-146a by these two prominent classes of human microbiota; and (iii) will discuss the role of molecular neurobiology and mechanistic contribution of polymicrobial infections to AD-type neuropathological change.

New Paradigms for the Study of Ocular Alphaherpesvirus Infections: Insights into the Use of Non-Traditional Host Model Systems

Ocular herpesviruses, most notably human alphaherpesvirus 1 (HSV-1), canid alphaherpesvirus 1 (CHV-1) and felid alphaherpesvirus 1 (FHV-1), infect and cause severe disease that may lead to blindness. CHV-1 and FHV-1 have a pathogenesis and induce clinical disease in their hosts that is similar to HSV-1 ocular infections in humans, suggesting that infection of dogs and cats with CHV-1 and FHV-1, respectively, can be used as a comparative natural host model of herpesvirus-induced ocular disease. In this review, we discuss both strengths and limitations of the various available model systems to study ocular herpesvirus infection, with a focus on the use of these non-traditional virus-natural host models. Recent work has demonstrated the robustness and reproducibility of experimental ocular herpesvirus infections in dogs and cats, and, therefore, these non-traditional models can provide additional insights into the pathogenesis of ocular herpesvirus infections.

Occurrence of viral DNA in paired samples of corneal rim and cornea preservation fluid

Corneal transplants have one of the highest success rates among all transplantological procedures. Corneas intended for transplantation are stored in a preservation fluid, which is then tested for bacterial and fungal infections. Among all analyses of infectious complications following corneal transplants, infections caused by bacteria or fungi are the most prominent. Surprisingly, however, apart from a few publications, there is a lack of data regarding the occurrence of viruses in donor corneas and the risk of transmitting these to their recipients. The intention of this research was therefore to determine the frequency with which human herpesvirus 1 (HHV-1), human herpesvirus 2 (HHV-2), and human adenovirus (HAdV) occur in transplanted corneal tissue, as well as in samples of preservation fluid. The study comprised 57 paired samples, with each pair consisting of a fragment of the corneal tissue remaining after its trepanation for transplantation surgery and a sample of corneal preservation fluid. Sample pairs were all tested for the presence of the DNA of three viruses (HHV-1, HHV-2, and HAdV) using real time PCR technique. Viral DNA was found in three of the tested corneas-HHV-1 DNA in one paired sample (1.8%) and adenovirus DNA in two single samples (3.5%). We postulate that virological testing of corneas for transplantation should be considered, particularly in the case of donors with increased risk factors for herpesvirus and adenovirus reactivation. J. Med. Virol. 89:732-736, 2017. © 2016 Wiley Periodicals, Inc.

Diagnosing of herpes simplex virus infections in suspected patients using real-time PCR

Background:

Herpes simplex virus infections are very common worldwide. The virus can cause infection in various body parts, especially eyes and the nervous system. Therefore, an early diagnosis and highly sensitive method is very helpful.

Objectives:

The present study sought to investigate the efficiency of Real-time TaqMan probe PCR in the diagnosis of HSV infection in suspected patients.

Patients and Methods:

In this study, 1566 patients with suspected HSV infections were enrolled. They aged 17 days to 96 years. The collected specimens were classified into four groups; cerebrospinal fluid (CSF) from HSE suspected individuals, samples from eye epithelial scraping, tear fluid or aqueous humor from herpes simplex keratitis (HSK) suspected patients, plasma of immune compromised patients and mucocutaneous collected samples from different body parts. The samples were analyzed by Real-time PCR assays.

Results:

In total, 44 (5.6%), 118 (26.8%), 23 (11.7%), 13 (44.8%) and 65 (45.5%) of 791 HSE, 407 HSK, 29 skin HSV, 143 oropharyngeal suspected patients and 196 patients with systemic HSV infection HSV had positive results by Real-time PCR assays, respectively.

Conclusions:

Real-time PCR assay, due to its high sensitivity and specificity, can help in early diagnosis and more effective treatment for patients. Also, it requires shorter hospital stay and promotes patients' survival.

Could polymerase chain reaction tests on conjunctival swabs be useful to diagnose herpetic keratitis?

INTRODUCTION

Diagnosis of HSV-1 keratitis (HK) is frequently based on clinical findings. Invasive specimens (corneal scrapings, biopsies) are required for microbiological diagnosis.

METHODS

Corneal scrapings and conjunctival swabs were collected on patients with/without clinical suspicion of HK from 2007 to 2012.

RESULTS

The sensitivity, specificity, positive and negative predictive values for conjunctival swabs by PCR was 77.8, 92.1, 84.4 and 88.3, respectively.

DISCUSSION

Conjunctival swabs by PCR may help in the diagnosis of HK, despite the limited sensitivity.

Herpes keratitis

Herpes simplex virus-1 (HSV-1) infects the majority of the world's population. These infections are often asymptomatic, but ocular HSV-1 infections cause multiple pathologies with perhaps the most destructive being herpes stromal keratitis (HSK). HSK lesions, which are immunoinflammatory in nature, can recur throughout life and often cause progressive corneal scaring resulting in visual impairment. Current treatment involves broad local immunosuppression with topical steroids along with antiviral coverage. Unfortunately, the immunopathologic mechanisms defined in animal models of HSK have not yet translated into improved therapy. Herein, we review the clinical epidemiology and pathology of the disease and summarize the large amount of basic research regarding the immunopathology of HSK. We examine the role of the innate and adaptive immune system in the clearance of virus and the destruction of the normal corneal architecture that is typical of HSK. Our goal is to define current knowledge of the pathogenic mechanisms and recurrent nature of HSK and identify areas that require further study.

Cellular changes of the corneal epithelium and stroma in herpes simplex keratitis: an in vivo confocal microscopy study

PURPOSE

To analyze the morphologic features of corneal epithelial cells and keratocytes by in vivo confocal microscopy in patients with herpes simplex keratitis (HSK) as associated with corneal innervation.

DESIGN

Prospective, cross-sectional, controlled, single-center study.

PARTICIPANTS

Thirty-one eyes with the diagnosis HSK and their contralateral clinically unaffected eyes were studied and compared with normal controls (n = 15).

METHODS

In vivo confocal microscopy (Confoscan 4; Nidek Technologies, Gamagori, Japan) and corneal esthesiometry (Cochet-Bonnet; Luneau Ophthalmologie, Chartres, France) of the central cornea were performed bilaterally in all patients and controls. Patients were grouped into normal (>5.5 cm), mild (>2.5-5.5 cm), and severe (<2.5 cm) loss of sensation.

MAIN OUTCOME MEASURES

Changes in morphologic features and density of the superficial and basal epithelial cells, as well as stromal keratocytes, were assessed by 2 masked observers. Changes were correlated to corneal sensation, number of nerves, and total length of nerves.

RESULTS

There was a significant and gradual decrease in the density of superficial epithelial cells in HSK eyes, with 852.50 ± 24.4 cells/mm(2) in eyes with severe sensation loss and 2435.23 ± 224.3 cells/mm(2) in control eyes (P = 0.008). Superficial epithelial cell size was 2.5-fold larger in HSK eyes (835.3 μm(2)) compared with contralateral or normal eyes (407.4 μm(2); P = 0.003). A significant number of hyperreflective desquamating superficial epithelial cells were present in HSK eyes with normal (6.4%), mild (29.1%), and severe (52.2%) loss of sensation, but were absent in controls. The density of basal epithelial cells, anterior keratocytes, and posterior keratocytes did not show statistical significance between patients and controls. Changes in superficial epithelial cell density and morphologic features correlated strongly with total nerve length, number, and corneal sensation. Scans of contralateral eyes did not show any significant epithelial or stromal changes compared with controls.

CONCLUSIONS

In vivo confocal microscopy reveals profound HSK-induced changes in the superficial epithelium, as demonstrated by increase in cell size, decrease in cell density, and squamous metaplasia. This study demonstrated that these changes correlate strongly with changes in corneal innervation.

Ocular herpes simplex virus: how are latency, reactivation, recurrent disease and therapy interrelated?

Most humans are infected with herpes simplex virus (HSV) type 1 in early childhood and remain latently infected throughout life. While most individuals have mild or no symptoms, some will develop destructive HSV keratitis. Ocular infection with HSV-1 and its associated sequelae account for the majority of corneal blindness in industrialized nations. Neuronal latency in the peripheral ganglia is established when transcription of the viral genome is repressed (silenced) except for the latency-associated transcripts and microRNAs. The functions of latency-associated transcripts have been investigated since 1987. Roles have been suggested relating to reactivation, establishment of latency, neuronal protection, antiapoptosis, apoptosis, virulence and asymptomatic shedding. Here, we review HSV-1 latent infections, reactivation, recurrent disease and antiviral therapies for the ocular HSV diseases.

Characterization of nonstructural protein 3 of a neurovirulent Japanese encephalitis virus strain isolated from a pig

BACKGROUND

Japanese encephalitis virus (JEV), as a re-emerging virus that causes 10,000-15,000 human deaths from encephalitis in the world each year, has had a significant impact on public health. Pigs are the natural reservoirs of JEV and play an important role in the amplification, dispersal and epidemiology of JEV. The nonstructural protein 3 (NS3) of JEV possesses enzymatic activities of serine protease, helicase and nucleoside 5'-triphosphatase, and plays important roles in viral replication and pathogenesis.

RESULTS

We characterized the NS3 protein of a neurovirulent strain of JEV (SH-JEV01) isolated from a field-infected pig. The NS3 gene of the JEV SH-JEV01 strain is 1857 bp in length and encodes protein of approximately 72 kDa with 99% amino acid sequence identity to that of the representative immunotype strain JaGAr 01. The NS3 protein was detectable 12 h post-infection in a mouse neuroblastoma cell line, Neuro-2a, and was distributed in the cytoplasm of cells infected with the SH-JEV01 strain of JEV. In the brain of mice infected with the SH-JEV01 strain of JEV, NS3 was detected in the cytoplasm of neuronal cells, including pyramidal neurons of the cerebrum, granule cells, small cells and Purkinje cells of the cerebellum.

CONCLUSIONS

The NS3 protein of a neurovirulent strain of JEV isolated from a pig was characterized. It is an approximately 72 kDa protein and distributed in the cytoplasm of infected cells. The Purkinje cell of the cerebellum is one of the target cells of JEV infection. Our data should provide some basic information for the study of the role of NS3 in the pathogenesis of JEV and the immune response.

Upregulation of mouse genes in HSV-1 latent TG after butyrate treatment implicates the multiple roles of the LAT-ICP0 locus

PURPOSE

To determine host response by gene expression in HSV-1 latent trigeminal ganglia (TG) after sodium butyrate (NaBu) treatment.

METHODS

Corneas of 6-week-old female BALB/c mice were scarified and inoculated with HSV-1 17Syn(+) (high phenotypic reactivator) or its mutant 17ΔPst(LAT(-)) (low phenotypic reactivator) at 10(4) plaque-forming units/eye. NaBu-induced viral reactivation was by intraperitoneal (IP) administration at postinfection (PI) day 28, followed by euthanasia after 1 hour. NaBu-treated, uninfected mice served as the control. The resultant labeled cRNA from TG isolated total RNA was hybridized to gene microarray chips containing 14,000 mouse genes. Quantitative real-time PCR was performed to confirm gene expression.

RESULTS

Differential induction of gene expression between 17Syn(+) and its mutant 17ΔPst(LAT(-)) was designated as NaBu-induced gene expression and yielded significant upregulation of 2- to 16-fold of 0.4% (56/14,000) host genes probed, comprising mainly nucleosome assembly and binding, central nervous system structural activity, hormonal activity, and signaling activity. Approximately 0.2% (24/14,000) of the host genes, mainly of the same functional categories were downregulated 3- to 11-fold. Immune activity was minor in comparison to our reports on gene expression during latency and heat stress induction. Euchromatin analysis revealed that the LAT-ICP0 locus is amenable to the effects of NaBu. Histone activity was detected by early transcription of histone cluster 2 H2be (Hist2h2be). CONCLUSIONS NaBu-induced reactivation of HSV-1 is twofold: drug action involving significant moderation of specific host epigenetic changes and failure to elicit or suppress immune activity at the early time point of 1 hour.

Ocular herpes simplex virus type 1: is the cornea a reservoir for viral latency or a fast pit stop?

PURPOSE

To present a review supporting and refuting evidence from mouse, rabbit, nonhuman primate, and human studies of herpes simplex virus type 1 (HSV-1) concerning corneal latency.

METHODS

More than 50 research articles on HSV-1 published in peer-reviewed journals were examined.

RESULTS

Infectious HSV-1 has been found in mouse denervated tissues and in tissues with negative cultures from the corresponding ganglion. However, the different mouse strains have shown varied responses to different strains of HSV, making it difficult to relate such findings to humans. Rabbit studies provide excellent evidence for HSV-1 corneal latency including data on HSV-1 migration from the cornea into the corneoscleral rim and on the distribution of HSV-1 DNA in the cornea. However, the available methods for the detection of infectious HSV-1 may not be sensitive enough to detect low-level infection. Infectious HSV-1 has been successfully isolated from the tears of nonhuman primates in the absence of detectable corneal lesions. The recurrence of corneal ulcers in nonhuman primates before the appearance of infectious HSV-1 in tears suggests that the origin of the HSV-1 is the cornea, rather than the trigeminal ganglion. Human studies presented evidence of both ganglion and corneal latency.

CONCLUSIONS

Understanding HSV-1 disease progression and the possibility of corneal latency could lead to more effective treatments for herpetic keratitis. However, it is unlikely that operational latency in the cornea will be definitively proven unless a new method with higher sensitivity for the detection of infectious virus is developed.

Corneal latency and transmission of herpes simplex virus-1

The transmission of herpes simplex virus (HSV)-1 by corneal transplantation has rarely been reported. It is believed that these cases have resulted either from reactivated virus traveling from the trigeminal ganglion to the cornea or from latent HSV-1 in the donor cornea itself. Studies of long-term viral presence in corneal tissue have sought to determine whether there is evidence of true non-neuronal latency, although there are problems in its definition. Recent studies provide new insights into neuronal latency, while similar HSV-1 gene regulation in the cornea may implicate corneal latency in pathophysiology and as a potential risk for transplant recipients. This issue has led to concerns over eye banking, which currently screens for other infectious agents but not HSV-1. Here we review the literature regarding corneal latency and the transmission of HSV-1.

Syndecan-1 and syndecan-2 play key roles in herpes simplex virus type-1 infection

Herpes simplex virus type 1 (HSV-1) is an important human pathogen and a leading cause of infectious blindness in the developed world. HSV-1 exploits heparan sulfate proteoglycans (HSPG) for attachment to cells. While the significance of heparan sulphate (HS) moieties in HSV-1 infection is well established, the role of specific proteoglycan core proteins in the infection process remains poorly understood. The objective of this study was to assess the roles of syndecan-1 and syndecan-2 core proteins in HSV-1 infection, both of which are expressed by many HSV-1 target cell types. Our results demonstrate that syndecan-1 and syndecan-2 gene silencing by RNA interference reduces HSV-1 entry, plaque formation and facilitates cell survival. Furthermore, HSV-1 infection increases syndecan-1 and syndecan-2 protein synthesis and a resultant increase in cell surface expression of HS. Our observations suggest that changes in syndecan-1 and syndecan-2 expression levels may be related to active viral infection. Taken together, our findings provide new insights into HSPG functions during HSV-1 entry and spread.

HSV-1 infection of human corneal epithelial cells: receptor-mediated entry and trends of re-infection

PURPOSE

The human cornea is a primary target for herpes simplex virus-1 (HSV-1) infection. The goals of the study were to determine the cellular modalities of HSV-1 entry into human corneal epithelial (HCE) cells. Specific features of the study included identifying major entry receptors, assessing pH dependency, and determining trends of re-infection.

METHODS

A recombinant HSV-1 virus expressing beta-galactosidase was used to ascertain HSV-1 entry into HCE cells. Viral replication within cells was confirmed using a time point plaque assay. Lysosomotropic agents were used to test for pH dependency of entry. Flow cytometry and immunocytochemistry were used to determine expression of three cellular receptors--nectin-1, herpesvirus entry mediator (HVEM), and paired immunoglobulin-like 2 receptor alpha (PILR-a). The necessity of these receptors for viral entry was tested using antibody-blocking. Finally, trends of re-infection were investigated using viral entry assay and flow cytometry post-primary infection.

RESULTS

Cultured HCE cells showed high susceptibility to HSV-1 entry and replication. Entry was demonstrated to be pH dependent as blocking vesicular acidification decreased entry. Entry receptors expressed on the cell membrane include nectin-1, HVEM, and PILR-α. Receptor-specific antibodies blocked entry receptors, reduced viral entry and indicated nectin-1 as the primary receptor used for entry. Cells re-infected with HSV-1 showed a decrease in entry, which was correlated to decreased levels of nectin-1 as demonstrated by flow cytometry.

CONCLUSIONS

HSV-1 is capable of developing an infection in HCE cells using a pH dependent entry process that involves primarily nectin-1 but also the HVEM and PILR-α receptors. Re-infected cells show decreased levels of entry, correlated with a decreased level of nectin-1 receptor expression.