Human herpes simplex virus keratitis: the pathogenesis revisted

The aim of this thesis is to elucidate pathogenic mechanisms of different forms of human HSV keratitis. HSV infection of the corneal epithelium causes a classical dendritic shaped lesion. Many studies could explain the development and growth in dendritic keratitis, but none of these found the anatomical substrate for the linear branching pattern. The most obvious explanation would be, that the shape of dendritic ulcers corresponds with the anatomical pattern of innervating nerves of the cornea. In chapter 2 a relationship between the shape of dendritic ulcers in infectious epithelial keratitis and the subbasal nerve plexus of the corneal epithelium is postulated. Recurrence of HSV keratitis is a common complication after PKP for corneal opacities resulting from HSV infection. After PKP, for reasons unrelated to HSV keratitis, epithelial defects may still be caused by HSV. In chapter 3 the incidence of newly acquired HSV keratitis after PKP is determined and possible contributing factors are assessed. Several possibilities as to the origin of the infecting HSV exist. These include reactivation oflatent virus in the trigeminal ganglion, horizontal spread, or transmission through the donor cornea. To test the assumption of graft-to-host transmission of HSV by PKP, surplus corneal material was examined for the presence of HSV DNA. Because the amount of viral DNA available could be very limited, a new method independent of viral culture, was developed to allow distinction between different virus strains. The newly developed technique was used to test our hypothesis that graft-to-host transmission of HSV is possible. This new method was used to determine the incidence of HSV-1 superinfection in patients with recurrent HSV keratitis. Although HSK has been studied extensively in the mouse model, it is not clear what triggers the immune response and to what extent the mouse data correlate with findings in human keratitis. The most logical idea, that virus-derived proteins are the eliciting factor for the immune response, has been ruled out in the experimental HSK mouse model. Alternative sources of the keratogenic antigens, like auto-antigens, have been suggested. Data on the pathogenesis of human HSK are limited. Therefore, in chapter 4 the antigenspecificity of corneal T cells in HSK patients was investigated. Besides this, corneas of patients with HSK were examined for the presence of corneal antigen reactive T cells (auto-reactive T cells). Chapter 5 provides a concise summary of the data generated in the framework of this thesis, and concludes with an overall discussion of the data and their possible impact on current ophthalmologic practice

Herpes simplex virus-specific T cells infiltrate the cornea of patients with herpetic stromal keratitis: no evidence for autoreactive T cells

PURPOSE: Herpetic stromal keratitis (HSK) is a T-cell-mediated inflammatory disease initiated by a herpes simplex virus (HSV) infection of the cornea. Recently, studies in the HSK mouse model have shown that the immunopathogenic T cells are directed against the HSV protein UL6 cross-reacting with an unknown corneal autoantigen. Whether this type of autoimmunity plays a role in human HSK was analyzed. METHODS: T-cell lines (TCLs) were generated from corneal buttons of 12 patients with different clinical stages of HSV-induced necrotizing stromal keratitis (n = 9) or immune stromal keratitis (n = 3). The initiating virus was identified by polymerase chain reaction and immunohistology performed on the corneal buttons. Peripheral blood mononuclear cells (PBMCs) were isolated, and B cell lines (BLCLs) were generated by transformation with Epstein-Barr virus. Proliferative responses of these intracorneal TCLs were determined by culturing T cells with autologous BLCLs infected with HSV-1, HSV-2, wild-type vaccinia virus (VV-WT), or VV expressing HSV-1 UL6 (rVV-UL6). Alternatively, T cells were incubated with PBMCs pulsed with human cornea protein extract. RESULTS: Irrespective of clinical diagnosis or treatment, T cells were recovered from the corneal buttons of all the 12 HSK patients. The intracorneal TCLs of 9 of the 12 HSK patients showed HSV-specific T-cell reactivity. In none of the TCLs, T-cell reactivity against HSV-1 UL6 or human corneal antigens was detected. CONCLUSIONS: These data suggest that the potentially immunopathogenic intracorneal T-cell response in HSK patients is directed to the initiating virus and not to a human corneal autoantigen or HSV-1 UL6

Corneal herpes simplex virus type 1 superinfection in patients with recrudescent herpetic keratitis

PURPOSE: Herpetic keratitis is a common sequel of a corneal infection with herpes simplex virus (HSV)-1. Recrudescent herpetic keratitis (RHK) may result in irreversible damage to the cornea. Recurrences may be caused by reactivation of endogenous HSV-1 or reinfection with exogenous HSV-1. The objective of this study was to determine the incidence and risk factors involved of HSV-1 superinfection in patients with RHK. METHODS: From 30 patients with RHK, sequential corneal HSV-1 isolates were genotyped by PCR amplification of the hypervariable regions located within the HSV-1 genes US1, US10/11, and US12. The clinical data from the patients obtained retrospectively were: ophthalmologic history, clinical picture during recurrences, number and time points of penetrating keratoplasty (PKP), and steroid or acyclovir treatment. RESULTS: Whereas the sequential corneal HSV-1 isolates of 19 (63%) of 30 patients had the same genotype (designated as group 1), the sequential isolates of 11 patients (37%) were genetically different (designated as group 2). Among the clinical data analyzed, only the time point of PKP was significantly different between the patient groups. A

Cluster of Symptomatic Graft-to-Host Transmission of Herpes Simplex Virus Type 1 in an Endothelial Keratoplasty Setting

PURPOSE: Descemet's membrane endothelial keratoplasty (DMEK) is becoming the gold standard to treat corneal endothelial dysfunctions worldwide. Compared with conventional penetrating keratoplasty, infectious complications after DMEK are ill defined. We describe the clinical picture of 2 DMEK recipients, operated on the same day and in the same clinic, who developed atypical herpes simplex virus type 1 (HSV-1) infection in the transplant recipient eye within days post-DMEK. Because recipients received cornea tissue from 2 different donors prepared by the same eye bank, the likelihood of a common HSV-1 source was determined. DESIGN: Case series. PARTICIPANTS: Two DMEK recipients who developed atypical intraocular HSV-1 disease shortly after surgery and surplus cornea specimens of 6 donors. METHODS: Surplus cornea donor (pre-DMEK cornea remnants and conditioned cornea storage and transport media) and recipient samples (post-DMEK aqueous humor) were assayed for HSV-1 DNA and infectious virus by real-time polymerase chain reaction (RT-PCR) and cell culture, respectively. Target-enriched whole viral genome sequencing was performed on HSV-1 DNA–positive ocular specimens. MAIN OUTCOMES MEASURES: Clinical picture of atypical intraocular HSV-1 infection post-DMEK and presence and homology of HSV-1 genomes between ocular specimens of DMEK donors and recipients. RESULTS: Herpes simplex virus type 1 DNA was detected in aqueous humor and donor cornea specimens of both DMEK cases, but not in the cornea remnants of 6 randomly selected donors processed by the same eye bank. Infectious HSV-1 was isolated from the cornea remnant and corresponding culture medium of 1 cornea donor. Notably, whole-genome sequencing of virus DNA-positive specimens demonstrated exceptionally high genetic similarity between HSV-1 strains in recipient and donor specimens of both DMEK cases. CONCLUSIONS: Data indicate cross-contamination of cornea grafts during DMEK preparation with subsequent graft-to-host HSV-1 transmission that caused atypical sight-threatening herpetic eye disease shortly after DMEK. Ophthalmologists should be aware that HSV-1 transmission by DMEK is possible and can lead to atypical ocular disease, a condition that can easily be prevented by taking appropriate technical and clinical measures at both eye bank and surgical levels

Amplification of reiterated sequences of herpes simplex virus type 1 (HSV-1) genome to discriminate between clinical HSV-1 isolates.

Herpes simplex virus type 1 (HSV-1)-related disease ranges from a localized, self-limiting illness to fatal disease in immunocompromised individuals. The corneal disease herpetic keratitis may develop after reactivation of a latent virus or reinfection with an exogenous herpesvirus. Molecular analysis of the virus involved may allow distinction between these two options. The HSV-1 genome contains several hypervariable regions that vary in numbers of reiterating regions (reiterations I to VIII [ReI to ReVIII]) between individual strains. Twenty-four HSV-1 clones, derived by subcloning of HSV-1 (strain F) twice in limiting dilutions, were tested in a PCR-based assay to analyze the stabilities of ReI, ReIII, ReIV, and ReVII. ReI and ReIII proved to vary in size upon subcloning, whereas ReIV and ReVII were stable. Subsequently, 37 unrelated isolates and 10 sequential isolates from five patients, all with HSV-1-induced keratitis, were genotyped for ReIV and ReVII. Of the 37 unrelated samples, 34 (92%) could be discriminated, while the genotypes of the viruses in sequential samples were identical for each individual. Conclusively, the data show that the approach presented allows the rapid and accurate discrimination of HSV-1 strains in studies that address the transmission and pathogenesis of HSV-1 infections

Trial-based cost-effectiveness analysis of ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) versus DSAEK

Purpose: To evaluate the cost-effectiveness of ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) versus standard DSAEK. Methods: A cost-effectiveness analysis using data from a multicentre randomized clinical trial was performed. The time horizon was 12 months postoperatively. Sixty-four eyes of 64 patients with Fuchs’ endothelial dystrophy were included and randomized to UT-DSAEK (n = 33) or DSAEK (n = 31). Relevant resources from healthcare and societal perspectives were included in the cost analysis. Quality-adjusted life years (QALYs) were determined using the Health Utilities Index Mark 3 questionnaire. The main outcome was the incremental cost-effectiveness ratio (ICER; incremental societal costs per QALY). Results: Societal costs were €9431 (US$11 586) for UT-DSAEK and €9110 (US$11 192) for DSAEK. Quality-adjusted life years (QALYs) were 0.74 in both groups. The ICER indicated inferiority of UT-DSAEK. The cost-effectiveness probability ranged from 37% to 42%, assuming the maximum acceptable ICER ranged from €2500–€80 000 (US$3071–US$98 280) per QALY. Additional analyses were performed omitting one UT-DSAEK patient who required a regraft [ICER €9057 (US$11 127) per QALY, cost-effectiveness probability: 44–62$29 271) per QALY, cost-effectiveness probability: 36–59%]. Furthermore, the ICER was €2101 (US$2581) per patient with clinical improvement in best spectacle-corrected visual acuity (≥0.2 logMAR) and €3274 (US$4022) per patient with clinical improvement in National Eye Institute Visual Functioning Questionnaire-25 composite score (≥10 points). Conclusion: The base case analysis favoured DSAEK, since costs of UT-DSAEK were higher while QALYs were comparable. However, additional analyses revealed no preference for UT-DSAEK or DSAEK. Further cost-effectiveness studies are required to reduce uncertainty