Lies Remeijer

Acyclovir-Resistant Corneal HSV-1 Isolates from Patients with Herpetic Keratitis

The prevalence and molecular characteristics of isolates from 173 immunocompetent patients with herpetic keratitis (HK) who were infected with acyclovir (ACV)-resistant (ACV(R)) corneal herpes simplex virus (HSV)-1 was determined. Isolates from 11 (6.4%) of the patients were ACV(R), and 9 of these 11 patients were refractory to therapy with ACV; the ACV(R) isolates from 5 and 1 of these 9 patients were cross-resistant to gancyclovir and to both gancyclovir and foscarnet, respectively. Of the 11 ACV(R) isolates, 10 had, in the thymidine kinase gene, mutations that presumably conferred the ACV(R) phenotype. These data demonstrate a relatively high prevalence of corneal HSV-1 ACV(R) isolates in patients with HK, which emphasizes the need to monitor for ACV susceptibility in patients with HK who are refractory to therapy with ACV.

Herpes simplex virus 1 transmission through corneal transplantation

Genetic characterisation of herpes simplex virus type 1 (HSV-1) DNA isolated from a donor cornea before and after corneal transplantation demonstrated the transmission of HSV-1 through transplantation. This study is the first to provide conclusive evidence for the transmission of HSV-1 by penetrating keratoplasty with subsequent reactivation of donor-derived HSV-1 in the transplanted cornea.

Acyclovir susceptibility and genetic characteristics of sequential herpes simplex virus type 1 corneal isolates from patients with recurrent herpetic keratitis.

PURPOSE The incidence and clinical significance of herpes simplex virus type 1 (HSV-1) acyclovir resistance were determined in patients with recurrent herpetic keratitis (RHK). METHODS Sequential corneal isolates (n = 39) from 15 immunocompetent patients with RHK were assayed for acyclovir susceptibility and genotyped by analyzing the hypervariable regions of the HSV-1 genes US1 and US12. The thymidine kinase (TK) gene of each isolate was sequenced, and the proportion of acyclovir-resistant viruses within isolates was determined. RESULTS Uniform acyclovir-resistant or acyclovir-sensitive sequential isolates were identified in 4 and 2 patients, respectively. Notably, the acyclovir susceptibility of sequential isolates changed from acyclovir sensitive to acyclovir resistant (5 patients) or from acyclovir resistant to acyclovir sensitive (3 patients). The acyclovir-resistant phenotype of the isolates correlated with the patients unresponsiveness to acyclovir therapy. Combined analyses of the TK gene and genotype of sequential isolates showed that acyclovir-sensitive isolates contained multiple acyclovir-resistant variants of the same virus and that an identical acyclovir-resistant HSV-1 strain reappeared in the patients cornea during RHK episodes. CONCLUSIONS Corneal HSV-1 isolates are mixtures of acyclovir-sensitive and acyclovir-resistant viruses that share the same genotype but have different TK sequences. Recovery of the same acyclovir-resistant virus during consecutive herpetic keratitis episodes suggests that acyclovir-resistant HSV-1 establishes latency and reactivates intermittently to cause acyclovir-refractory RHK.

Newly Acquired Herpes Simplex Virus Keratitis after Penetrating Keratoplasty

BACKGROUND After penetrating keratoplasty for reasons unrelated to herpes simplex virus (HSV) keratitis, any nonspecific epithelial defect may still be caused by HSV. The purpose of this study is to determine the incidence of newly acquired herpetic keratitis and to assess contributing factors. METHODS The authors retrospectively studied the results of 2398 penetrating keratoplasties performed between 1980 and 1995. Three typical case histories are discussed. RESULTS Of 2112 patients in whom the primary diagnosis was not related to HSV keratitis, 18 presented with epithelial herpetic keratitis in their corneal graft. The incidence of newly acquired herpetic keratitis after penetrating keratoplasty was 1.2 per 1000 person-years. In most cases, the infection occurred in the first 2 years after the transplantation. Most often, well-known reactivating stimuli could have caused the HSV infection. CONCLUSIONS Herpes simplex virus keratitis may develop after penetrating keratoplasty even without a clinical history of HSV in the host. Thus, HSV should be considered in the differential diagnosis of a postpenetrating keratoplasty epithelial defect. The high incidence of this infection in the first 2 years after such surgery suggests a causal relation between corneal transplantation and the HSV infection.

Effect of oral acyclovir after penetrating keratoplasty for herpetic keratitis: a placebo-controlled multicenter trial.

OBJECTIVE To determine the prophylactic effect of oral acyclovir on the recurrence rate of herpetic eye disease after penetrating keratoplasty. DESIGN A randomized, double-masked, placebo-controlled multicenter trial. PARTICIPANTS Sixty-eight consecutive patients (68 eyes) with corneal opacities due to herpetic eye disease who underwent penetrating keratoplasty. INTERVENTION Oral acyclovir 400 mg twice daily or placebo tablets for 6 months. MAIN OUTCOME MEASURES The recurrence rate of herpetic eye disease-related events and rejection episodes, proven by viral cell culture or polymerase chain reaction. RESULTS During the 2-year follow-up period, there were 3 culture-proven herpetic eye disease recurrences in the acyclovir group and 9 in the placebo group. Lifetime survival analysis of the probability of remaining free from recurrence revealed a significantly reduced risk of recurrent herpetic disease in the acyclovir-treated group. CONCLUSION This study suggests that oral acyclovir effectively prevents herpes-related recurrences after penetrating keratoplasty in herpetic eye disease.

Identification and Characterization of Herpes Simplex Virus-Specific CD4+ T Cells in Corneas of Herpetic Stromal Keratitis Patients

Herpetic stromal keratitis (HSK) is a corneal disease initiated by a herpes simplex virus (HSV) infection with a postulated T cell-mediated immunopathology. To study the antigen specificity of cornea-infiltrating T cells in HSK patients, T cells were isolated and expanded by mitogenic stimulation from corneas of 2 patients with HSV-1-mediated HSK. A substantial number of the T cell clones (TCCs) obtained from these T cell lines were HSV-specific. All HSV-specific TCCs were of the CD3+CD4+CD8- phenotype. These TCCs responded to autologous HSV-infected corneal keratocytes, which expressed HLA class II molecules following incubation with interferon-gamma. Upon HSV-specific stimulation, all TCCs secreted interleukin-4, interleukin-5, and interferon-gamma. The data presented suggest that HSV-specific CD4+ T cells play a role in the immunopathogenesis of HSK in humans and that corneal keratocytes may act as antigen-presenting cells in this local T cell response.

Age-related risk factors, culture outcomes, and prognosis in patients admitted with infectious keratitis to two Dutch tertiary referral centers.

Purpose: To assess age-related risk factors (RFs), microbiologic profile, and prognosis of infectious keratitis and create guidelines for prevention and treatment. Methods: Retrospective review of patients with infectious keratitis admitted to 2 Dutch tertiary referral centers from January 2002 to December 2004. Results: Forty-nine patients were admitted to the Academic Medical Center (Amsterdam) and 107 to the Rotterdam Eye Hospital. Mean age was 56.6 ± 24.4 (SD) years; 49.4% were ≥60 years of age. The most common RFs among the elderly were systemic illness (36.4%), ocular surgery (33.8%), topical steroids (26%), blepharitis (20.8%), and herpetic eye disease (28.6%). This was significantly different from the most common RFs among younger patients (contact lens wear, 62.7%; χ2, P = 0.000). Gram-negative infections predominated (52.3%) and were more prevalent among younger patients (χ2, P = 0.000). Gram-positive infections prevailed among the elderly. Untreated patients had higher culture positive rates (68.7%) than patients treated with antibiotics before culturing (41.3%; χ2, P = 0.001). Elderly patients had a higher risk of perforations than younger patients (27.6% vs. 9.9%), a worse prognosis (mean VA, 6/30 vs. 6/10), and more often needed surgery (57.1% vs. 23.4%; P < 0.005 in all cases). Conclusions: Infectious keratitis is a more severe disease in elderly than in younger patients with more complications and a worse prognosis. Elderly patients have multiple and more diverse risk factors, making prevention difficult. Prevention should aim at minimizing topical steroid use and controlling blepharitis, ocular surface disease, and herpetic eye disease. Initial antibiotic treatment should include sufficient coverage of Gram-positive pathogens.

Endothelial involvement in herpes simplex virus keratitis: an in vivo confocal microscopy study.

PURPOSE To describe the appearance, frequency, and clinical consequences of corneal endothelial involvement in human herpes simplex virus (HSV) keratitis as seen by in vivo confocal microscopy (IVCM). DESIGN Prospective observational case series. PARTICIPANTS A total of 285 patients with HSV keratitis who visited the cornea department of the Rotterdam Eye Hospital between May 2005 and May 2008. The control groups comprised the unaffected fellow eyes of patients with HSV keratitis, the eyes of 58 healthy volunteers, and the affected eyes of 62 patients with inflammatory corneal disorders other than HSV. METHODS We examined the eyes of all participants by IVCM and slit-lamp examination. For IVCM, corneas were scanned with Confoscan 3 or 4 (Nidek Technologies, Albignasego, Padova, Italy). MAIN OUTCOME MEASURES All IVCM examinations were qualitatively reviewed for signs of endothelial deviations characteristic of endotheliitis. Endothelial cell density (ECD) was evaluated on the first and last visits of patients who were followed for more than 100 days. The differences in ECDs were calculated and converted to percent ECD change per year. RESULTS Endothelial alterations characteristic of endotheliitis were detected by IVCM in 107 of 250 patients with HSV keratitis (43%). These deviations consisted of pseudoguttata, enlarged intercellular gaps, infiltration of inflammatory cells into the endothelial layer, loss of defined cell boundaries, spot-like holes, and endothelial denudation. All of these signs disappeared with appropriate antiviral and anti-inflammatory treatment. However, the endothelium in eyes with endotheliitis-characteristic alterations showed a significant decrease in ECD (10.3% per year) compared with healthy fellow eyes. CONCLUSIONS IVCM allows earlier detection of endothelial alterations in patients with HSV keratitis compared with slit-lamp examination. Although endotheliitis-specific alterations appear to resolve, the corneal endothelium can become irreversibly damaged.

Latent Acyclovir-Resistant Herpes Simplex Virus Type 1 in Trigeminal Ganglia of Immunocompetent Individuals

Specific mutations within the hypervariable herpes simplex virus (HSV) gene thymidine kinase (TK) gene lead to acyclovir (ACV) resistance. To uncover the existence of latent ACV-resistant (ACV(R)) HSV-1, we determined the genetic and functional variability of the HSV-1 TK gene pool in paired trigeminal ganglia (TG) of 5 immunocompetent individuals. The latent virus pool consisted of a donor-specific HSV-1 quasispecies, including one major ACV-sensitive (ACV(S)) and multiple phylogenetic-related minor ACV(S) and ACV(R) TK variants. Contrary to minor variants, major TK variants were shared between paired TG. The data demonstrate the coexistence of phylogenetic-related ACV(S) and ACV(R) latent HSV-1 in human TG.

Normative database for corneal backscatter analysis by in vivo confocal microscopy

PURPOSE To ascertain the sex and age relatedness, diurnal variation, and repeatability of backscatter measurement in the normal human cornea. METHODS Seven corneal backscatter variants were measured by in vivo confocal microscopy (IVCM) in both normal eyes (n = 314) of 157 healthy subjects. These subjects were assigned to one or more of three groups. The sex and age relatedness of corneal backscatter were assessed in group 1 (n = 300), which comprised 75 men and 75 women evenly distributed over five age categories. To assess diurnal variation, eyes in group 2 (n = 40) were measured four times a day, at 3-hour intervals. The eyes in group 3 (n = 50) were examined four times a year to determine intersession repeatability. Intrasession repeatability was determined by performing all IVCM examinations in duplicate. Linear mixed models were used to assess the effects of sex, age, and time of measurement on corneal backscatter. RESULTS Mean corneal backscatter was 3.5% higher in men (P = 0.003). From the age of 50 years, backscatter increased significantly in the anterior stroma (P = 0.0003). A small but statistically significant diurnal variation was found in all seven backscatter variants (P < 0.01). The test-retest coefficient of variation of mean corneal backscatter was 5.3%, comprising intra- and intersession repeatability. CONCLUSIONS Sex and time of measurement significantly affect corneal backscatter measured by IVCM, whereas age affects only backscatter in the anterior stroma. All three factors should be taken into account when conducting scientific research. For ophthalmic practice, the authors suggest ignoring these factors and propose a generalized normal range and minimum detectable change for each backscatter variant.