Detection of herpes simplex virus type 1, 2 and varicella zoster virus DNA in recipient corneal buttons

PCR testing for herpesviruses in aqueous humor samples from patients with and without clinical corneal endothelial graft rejection

To compare prevalence of positive PCR tests for herpesviruses between patients with and without a history of clinical corneal endothelial allograft rejection (AGR). Retrospective cross-sectional study with two-group comparison. A total of 307 aqueous humor (AH) samples from 235 Patients and 244 eyes who underwent penetrating keratoplasty or Descemet membrane endothelial keratoplasty or had a diagnostic AH aspiration due to clinical AGR between 2019 and 2023 were tested for DNA of herpes simplex virus (HSV), varicella-zoster virus (VZV), cytomegalovirus (CMV), and Epstein-Barr virus (EBV). PCR test results were compared between the two groups (with/without AGR). Another sub-analysis examined the results of patients without a history of herpetic keratitis. A total of 8% of eyes with clinical AGR (9/108) had a positive PCR result for one of the herpesviruses (HSV:3, CMV:3, EBV:2, VZV:1). All patients in the group without AGR had negative PCR results for all previous viruses (0/136). The difference was statistically significant (p < 0.001). The sub-analysis of eyes without a history of herpetic keratitis also revealed significantly more positive herpes PCR results (7/87) in eyes with AGR than in eyes without AGR (0/42, p = 0.005). Clinical AGR after keratoplasty shows a significant correlation to viral replication. Herpetic infection and AGR could occur simultaneously and act synergistically. Timely differentiation between active herpetic infection and/or AGR is pivotal for proper treatment and graft preservation.

Herpes simplex virus, varicella-zoster virus and cytomegalovirus keratitis: Facts for the clinician

Keratitis due to Herpes simplex virus (HSK), Varicella-Zoster virus (VZK) and Cytomegalovirus remains a frequent source of concern for many ophthalmologists. They are a frequent cause of emergency consultations at eye care centers and carry the risk of permanent loss of visual acuity or visual quality and/or chronic neurotrophic keratitis, resulting in a significant decrease in the quality of life. HSK and VZK can affect the corneal epithelium, stroma, or endothelium or a combination of layers. In contrast, most cases of CMV keratitis present as isolated endothelitis (CMVE), a clinical entity that has been described within the last 2 decades. These three types of viral keratitis are characterized by a high frequency of recurrences and each new episode increases the risk of sequelae. Hence, ophthalmologists must adapt the treatment to the clinical presentation of each recurrent episode in order to mitigate the immediate consequences of viral replication and the immune response on corneal transparency. In patients with frequent recurrences, preventive long-term antiviral treatment is strongly recommended. However, in some rare cases, continuous exposure to antivirals may promote the emergence of resistant viral strains, which can be difficult to manage. In the future, the introduction of new antiviral drugs, with differing modes of action compared to current medical therapy, could be an alternative until a truly effective preventive solution, such as a vaccine, is available.

Prevalence of Herpesvirus DNA in Corneal Transplant Recipients

Purpose: Graft failure after penetrating keratoplasty (PK) is a serious complication, especially in eyes with herpetic keratitis (HK). This study evaluated the prevalence and graft survival of herpes simplex virus type 1 (HSV-1) and varicella zoster virus (VZV) DNA in recipient corneas during PK. Methods: The retrospective study was performed at the Department of Ophthalmology at University Hospital in Mainz, Germany. We analyzed data from every patient who underwent PK between January 2020 and June 2021. According to our clinical routine, we performed HSV-1 and VZV polymerase chain reaction (PCR) on all excised corneal buttons regardless of the primary clinical diagnosis. Results: We included 112 eyes of 112 consecutive patients who underwent PK. At the time of PK, 91 (81.25%) patients had no history of HK and 21 (18.75%) patients did. The recipient corneas of 91 patients without a history of HK tested positive for HSV-1 DNA in 12 (13.2%) eyes, for VZV DNA in 3 (3.3%) eyes, and for HSV-1 and VZV DNA simultaneously in 2 (2.2%) eyes. The recipient corneas of 21 patients with a preoperative history of HK tested positive for HSV-1 DNA in 13 (61.9%) eyes and VZV DNA in 1 (4.8%) eye. All patients with positive herpes DNA and no history of HK prior to PK received antiherpetic treatment and had a 100% graft survival rate after 1 year. Conclusions: We found herpesvirus DNA in 18.7% of recipient corneas without clinical suspicion or history of herpes keratitis. This suggests the need of routine HSV-1 and VZV PCR testing in all explanted corneas regardless of clinical suspicion, to detect, treat and prevent possible recurrence of herpes infection in corneal grafts and support graft survival.

The presence and impact of herpes virus DNA in recipient cornea and aqueous humor on graft survival following penetrating keratoplasty

BACKGROUND/PURPOSE

Reactivation of herpes viruses poses threat to corneal graft survival. This study evaluated the presence of herpes simplex virus type 1 (HSV-1), HSV type 2 (HSV-2), and cytomegalovirus (CMV) DNA in recipient corneas and the aqueous humor of patients undergoing penetrating keratoplasty (PKP), and the impact on graft survival.

METHODS

This retrospective study reviewed 90 eyes of 71 patients underwent PKP between 2008 and 2016. Cornea and aqueous humor samples were sent for polymerase chain reaction (PCR) testing for viral DNA. The main outcomes were PCR results and graft survival.

RESULTS

Recipient corneas tested positive for HSV-1 in 47 eyes (52.2%), for HSV-2 in 24 eyes (26.7%), and for CMV in seven eyes (7.8%). Aqueous humor tested positive for HSV-1 in 44 eyes (48.9%), for HSV-2 in 25 eyes (27.8%), and for CMV in eight eyes (8.9%). The presence of aqueous HSV-1 DNA was associated with higher risk of graft failure (p = 0.005), whereas corneal HSV-1 DNA was not. The presence of HSV-2 DNA had no significant impact on graft survival. Aqueous CMV DNA was associated with higher risk of graft failure in univariate model, but not in multivariate model.

CONCLUSION

There were high positive rates of HSV-1, HSV-2, and CMV DNA in recipient corneas and aqueous humor at the time of PKP, even among patients not suspected of latent viral infection. The presence of aqueous HSV-1 DNA was associated with higher risk of graft failure.

[Results of laser confocal microscopy of the cornea in viral uveitis (a preliminary report)]

Herpesviruses involve neurotropic activity (they affect nerve cells) and have the ability to induce an immune response (a special tropism for immune tissue), which provides a valid reason for studying the possibilities of visualizing nerve fibers of the cornea and Langerhans cells (LC) in viral uveitis (with prospective applications in early diagnosis).

PURPOSE

To evaluate the results of laser corneal confocal microscopy (CCM) in viral uveitis of varying localization.

MATERIAL AND METHODS

The main study group included 23 patients (23 eyes) diagnosed with unilateral herpesviral uveitis (chorioretinitis), the patients' age varied from 18 to 79 years. The control group comprised 19 healthy volunteers (38 eyes) aged 20 to 75 years. In addition, the paired eyes of the main group patients were examined. In all patients, standard ophthalmologic examination was complemented with CCM performed on the HRT III device with a corneal module, followed by analysis of the course and structure of corneal nerve fibers (CNF) using copyrighted software Liner 1.2.

CONCLUSION

The preliminary results achieved in this study outline the prospects for further research on the state of cornea (in particular, changes in the course and structure of CNF, and the presence of dendritiform cells of Langerhans) with laser CCM in patients with uveitis of various etiologies. These morphological changes also has potential use as diagnostic markers of inflammation of the uveal tract. The main criteria for assessing the state of cornea in viral uveitis include the following: increased tortuosity of CNF, increase in the number and size of Langerhans cells. Further research - in particular, studying the integrated use of diagnostic methods necessary for the verification of viral uveitis, as well as detailed analysis of the history and clinical picture of the disease - is required to substantiate the inclusion of laser confocal microscopy method in the algorithm for the diagnosis of viral uveitis.

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.

Bilateral tear film alterations in patients with unilateral quiescent herpes simplex keratitis

PURPOSE

To evaluate bilateral tear function and corneal sensitivity in patients with unilateral quiescent herpes simplex keratitis (HSK) and determine the correlation between corneal sensitivity and tear secretion in both eyes.

METHODS

Thirty-five patients diagnosed with unilateral quiescent HSK and 35 heathy controls were included in this study. Bilateral tear osmolarity, Schirmer's test, the tear break-up time (TBUT) and corneal sensitivity were measured in all participants.

RESULTS

In the HSK group, both eyes demonstrated a significant increase in tear osmolarity, and a decrease in Schirmer's test and the TBUT compared with healthy controls (All p < 0.001). The bilateral tear osmolarity and Schirmer's test were similar, but the TBUT (4.9 ± 2.1 versus 7.4 ± 2.0 second; p < 0.001) and corneal sensitivity (35.1 ± 1.9 versus 54.3 ± 0.8 mm; p < 0.001) were significantly lower in the affected eyes. The bilateral tear osmolarity, Schirmer's test and the TBUT were significantly correlated with corneal sensitivity of the affected eye (All p < 0.001). When corneal sensitivity of the unaffected eye was treated as a control variable, tear osmolarity (R = -0.626, p < 0.001), Schirmer's test (R = 0.739, p < 0.001) and the TBUT (R = 0.691, p < 0.001) of the unaffected eyes were still significantly correlated with the corneal sensitivity of the affected eyes.

CONCLUSIONS

Unilateral quiescent HSK causes bilateral tear impairment, which depends on the loss of corneal sensitivity in the affected eye. In the affected eye with severe corneal sensitivity loss, bilateral dry eye occurred.

High-Risk Corneal Graft Rejection in the Setting of Previous Corneal Herpes Simplex Virus (HSV)-1 Infection

Purpose

The “high-risk phenotype” of corneal graft recipients is considered to be related to preexisting vascularization such as that associated with herpes simplex virus-1 (HSV-1) keratitis (HSK). The purpose of this study was to investigate the immunologic mechanisms underlying accelerated corneal graft rejection using a mouse model of HSK.

Methods

Herpes simplex virus type 1 keratitis was induced in BALB/c mice. Syngeneic and allogeneic (C57BL/6 mice) corneal grafts were performed in mice with HSK at different times after infection. Some grafts were performed on HSV-infected CD4 T cell–deficient BALB/c mice. Clinical, histologic, immunologic, and virus detection studies were performed on samples of cornea, draining lymph node (LN), and trigeminal ganglion (TG) cells.

Results

Corneal grafts in mice with HSK rejected with higher frequency and more rapid tempo compared with grafts in uninfected mice. In corneas with HSK and vascularization at the time of grafting, both syngeneic and allogeneic corneal grafts failed with similar frequency and tempo. However, in the absence of preexisting inflammation and vascularization, syngeneic grafts were accepted when the grafts were performed at a late time point after HSV infection (42 days), whereas allografts were rejected at this time. In contrast, syngeneic grafts in nonvascularized HSV-infected recipients failed if they were performed within 10 days of HSV infection, an effect that was dependent on CD4 T cells, as demonstrated using CD4 deficient mice. Importantly, a variably sustained but strongly positive anti-HSV T-cell response was detected in allografted HSK recipients with a similar but lesser response in syngeneic hosts.

Conclusions

A previous HSV-1 corneal infection predisposes donor grafts to a high risk of failure by both innate and adaptive immune mechanisms in which an anti-HSV CD4 T-cell response plays a prominent role.

Do Unilateral Herpetic Stromal Keratitis and Neurotrophic Ulcers Cause Bilateral Dry Eye?

PURPOSE

To evaluate and compare the ocular surface condition in herpetic interstitial stromal keratitis and neurotrophic ulcer groups and their normal fellow eyes.

METHODS

In this observational, cross-sectional case-control study, 85 consecutive patients were included, including 56 cases of treated herpetic interstitial keratitis and 29 patients with neurotrophic ulcers. Fifty-six age- and sex-matched participants were also recruited from a normal population as the control group. We evaluated and scored the subjective and objective measures of dry eye for both eyes of all patients. Then, we compared the score of the groups with one another and also with the control group. The main outcome measures were the discomfort level, visual symptoms of dry eye, conjunctival injection, conjunctival staining, corneal staining, corneal tear signs of dry eye, meibomian gland dysfunction, tear break-up time, Schirmer test score with anesthesia, and tear osmolarity.

RESULTS

The normal fellow eye of the herpetic keratitis group had significantly higher discomfort levels (1.4 ± 0.9 vs. 1.3 ± 0.5, P = 0.003), visual symptoms (1.7 ± 0.8 vs. 1.3 ± 0.7, P = 0.002), tear break-up time (8.3 ± 3.2 vs. 12.1 ± 3.3 seconds, P = 0.003), Schirmer test scores (9.2 ± 3.9 vs. 12.9 ± 3 mm, P = 0.04), and tear osmolarity (9.2 ± 3.9 vs. 12.9 ± 3 mm, P = 0.003) in comparison with normal controls. The normal fellow eyes of the neurotrophic ulcer group had significantly worse values for discomfort level (1.9 ± 0.9 vs. 1.3 ± 0.5, P < 0.001), tear break-up time (7.9 ± 4 vs. 12.1 ± 3.3, P = 0.004), Schirmer test score (8.1 ± 3.9 vs. 12.9 ± 3, P = 0.005), and tear osmolarity (295 ± 9.2 vs. 292.7 ± 5.9, P = 0.02) compared with normal controls.

CONCLUSIONS

Both eyes of patients with neurotrophic ulcer and interstitial herpetic keratitis have a significantly poorer ocular surface condition compared with that of normal controls.

Herpes zoster epidemiology, management, and disease and economic burden in Europe: a multidisciplinary perspective

Herpes zoster (HZ) is primarily a disease of nerve tissue but the acute and longer-term manifestations require multidisciplinary knowledge and involvement in their management. Complications may be dermatological (e.g. secondary bacterial infection), neurological (e.g. long-term pain, segmental paresis, stroke), ophthalmological (e.g. keratitis, iridocyclitis, secondary glaucoma) or visceral (e.g. pneumonia, hepatitis). The age-related increased incidence of HZ and its complications is thought to be a result of the decline in cell-mediated immunity (immunosenescence), higher incidence of comorbidities with age and social-environmental changes. Individuals who are immunocompromised as a result of disease or therapy are also at increased risk, independent of age. HZ and its complications (particularly postherpetic neuralgia) create a significant burden for the patient, carers, healthcare systems and employers. Prevention and treatment of HZ complications remain a therapeutic challenge despite recent advances. This is an overview of the multidisciplinary implications and management of HZ in which the potential contribution of vaccination to reducing the incidence HZ and its complications are also discussed.

Herpes simplex virus 2 infection: molecular association with HIV and novel microbicides to prevent disease

Infection with herpes simplex viruses is one of the most ancient diseases described to affect humans. Infection with these viruses produces vexing effects to the host, which frequently recur. Infection with herpes simplex viruses is lifelong, and currently there is no vaccine or drug to prevent or cure infection. Prevalence of herpes simplex virus 2 (HSV-2) infection varies significantly depending on the geographical region and nears 20 % worldwide. Importantly, HSV-2 is the first cause of genital ulcers in the planet. HSV-2 affects approximately 500 million people around the globe and significantly increases the likelihood of acquiring the human immunodeficiency virus (HIV), as well as its shedding. Thus, controlling HSV-2 infection and spread is of public health concern. Here, we review the diseases produced by herpes simplex viruses, the factors that modulate HSV-2 infection, the relationship between HSV-2 and HIV and novel therapeutic and prophylactic microbicides/antivirals under development to prevent infection and pathological outcomes produced by this virus. We also review mutations associated with HSV-2 resistance to common antivirals.

Role of molecular diagnostics in ocular microbiology

Although microbial culture remains the gold standard for diagnosis of many ocular infections, the technique is limited by low yield, inability to detect certain organisms, and potentially long delays to results. DNA-based molecular diagnostic techniques use detection of specific nucleic acid sequences as evidence for presence of suspected pathogens. The polymerase chain reaction (PCR) is a powerful molecular biology technique that allows for detection of fewer than 10 copies of pathogen genome. Recent technical advances in PCR have permitted quantitation of pathogen load using quantitative PCR (qPCR), and have permitted multiplexing of primer sets. Use of pan-bacterial and pan-fungal primers for ribosomal DNA sequences has allowed diagnosis of bacterial and fungal infections using molecular techniques. In this review, we highlight recent advances in the application of PCR to the diagnosis of anterior segment and posterior segment ocular infectious diseases.

Varicella-zoster virus keratitis with asymptomatic conjunctival viral shedding in the contralateral eye

Purpose

To report a case of varicella-zoster virus (VZV) keratitis with detection of VZV DNA in the tear fluid of not only the symptomatic eye but also the contralateral asymptomatic eye by polymerase chain reaction (PCR).

Methods

This is a case report. A 63-year-old otherwise healthy woman presented with circular corneal ulcer and stromal opacity with infiltration accompanied by mild conjunctival and ciliary injections in the left eye. Bacterial cultures of the corneal scrapings and virus PCR analyses of tear fluid from both eyes were performed.

Results

No pathogen was found by bacterial cultures. PCR was negative for Acanthamoeba, herpes simplex virus and cytomegalovirus, but positive for VZV. VZV DNA was also detected in the unaffected eye. Based on the diagnosis of VZV keratitis, oral valacyclovir and acyclovir eye ointment were administered to the corneal infected eye. The infected eye was healed and VZV DNA turned negative in the tear fluid of the treated eye after 6 months of treatment; however, VZV DNA was still positive in the tear fluid of the contralateral eye.

Conclusions

To our knowledge, this is the first case report of the detection of VZV DNA in the tear fluid of both affected and unaffected eyes in a patient with VZV keratitis. Asymptomatic conjunctival shedding of VZV may continue in the healthy unaffected eye in VZV keratitis patients.

Herpes simplex epithelial and stromal keratitis: an epidemiologic update

Herpes simplex virus (HSV) is associated with a variety of ocular diseases, including epithelial and stromal keratitis. HSV can cause stromal opacification and is believed to be the leading cause of infectious blindness in the developed world. An improved understanding of the global burden of HSV keratitis, including the incidence of severe vision loss, could have a significant effect on prevention and treatment and place it in perspective among causes of corneal ulceration. We found that the global incidence of HSV keratitis is roughly 1.5 million, including 40,000 new cases of severe monocular visual impairment or blindness each year. We also discuss relevant epidemiologic issues regarding HSV epithelial and stromal disease.

The kinetics of herpes virus on the ocular surface and suppression of its reactivation

Herpes simplex virus type 1 (HSV-1) establishes a latent infection in sensory neurons that can sometimes be reactivated. HSV-1 keratitis often recurs and can be vision threatening. Reactivation of the latent virus can be stimulated by stress, immunosuppression, trauma, adrenergic iontophoresis, and UV radiation. Healthy and asymptomatic individuals are known to shed HSV-1, and this is a major factor in the spread of the virus. We investigated the frequency of shedding of HSV-1 DNA in tears of dry eye patients and individuals with conjunctivitis. Subjects were divided into 3 groups: normal (12 eyes), dry eye (11 eyes), and conjunctivitis (15 eyes). Quantitative real-time polymerase chain reaction was used for HSV DNA detection. The incidences of HSV positivity in the normal, dry eye, and conjunctivitis groups were 1 of 12 (8.3%), 3 of 11 (27.3%), and 4 of 15 (26.7%), respectively. We have previously shown that bromfenac sodium eye drops, intramuscular adenosine monophosphate, and geldanamycin effectively lower HSV-1 recurrence rates in a mouse model. Recently, we also found that nuclear factor κ-B, an IκB kinase-β inhibitor, could be a candidate for reducing HSV-1 reactivation. We sampled recipients' corneal buttons during keratoplasty and performed polymerase chain reaction. Cytomegalovirus (CMV) DNA was detected in corneas obtained from some patients, and the copy number of the detected CMV DNA was quantified. CMV DNA-positive samples were taken from 2 of the 3 patients with ocular pemphigoid; thus, in future work, the relationship between CMV in the cornea and the incidence/onset of ocular diseases of the anterior segment needs to be evaluated.

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.

The quantitative detection of herpes simplex virus, varicella zoster virus, and cytomegalovirus DNAs in recipient corneal buttons

PURPOSE

We detected herpes simplex virus types 1 (HSV-1) and 2 (HSV-2), varicella zoster virus (VZV), and cytomegalovirus (CMV) DNAs in recipient corneal buttons taken at the time of penetrating keratoplasty.

METHODS

Twenty-seven corneal buttons were obtained from 27 patients (10 men and 17 women), 7 of whom had a history of HSV keratitis. Excised corneal buttons were immediately frozen in liquid nitrogen in the operating theater and then stored at -80°C until DNA extraction. The detection of HSV-1, HSV-2, VZV, and CMV DNAs was carried out by a nested polymerase chain reaction (PCR) method. The genome copy numbers for the nested PCR-positive samples were subsequently quantified by real-time PCR.

RESULTS

HSV-1, HSV-2, VZV, and CMV DNAs were detected in 10, 1, 9, and 2 of the 27 recipient corneal buttons, respectively. HSV-1 or HSV-2 DNAs were also detected in 5 of 7 patients with a history of HSV keratitis. Both CMV-positive patients (patients 2 and 3) had ocular pemphigoid. Among the nested PCR-positive samples, 2 HSV-1, 1 HSV-2, 1 VZV, and 1 CMV sample could be quantified by real-time PCR. Copy numbers ranged from 19 to 928 copies.

CONCLUSIONS

All 4 herpesviruses, including CMV, were detected in the corneal buttons. The relationship between CMV in the cornea and ocular diseases of the anterior segment should be further evaluated.

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.

Human herpes simplex virus keratitis: the pathogenesis revisited

Infections with several members of the human herpesviruses are the cause of significant ocular morbidity. Of the human herpesviruses, HSV-1 is the most frequent cause of primary and recurrent eye disease. Despite the availability of effective antiviral treatment, recurrent HSV-1 infection continues to be the leading cause of corneal blindness in industrialized nations. This review recapitulates the current insights in the role of the virus and the intra-corneal T cell response involved in the pathogenesis of human HSV-1-induced keratitis.

Diagnosis of herpes simplex virus-1 keratitis: Comparison of Giemsa stain, immunofluorescence assay and polymerase chain reaction

PURPOSE

To evaluate three different diagnostic tests against the gold standard of viral isolation, in the diagnosis of HSV-1 keratitis.

METHODS

Corneal scrapings from 170 patients with clinically suspected HSV keratitis were tested by; 1) Giemsa staining procedure for the presence of multinucleated giant cells and lymphocytes, 2) immunofluorescence assay for HSV-1 antigen, 3) polymerase chain reaction (PCR) for HSV-1 DNA and 4) virus isolation by shell vial culture in SIRC (Rabbit corneal epithelial cell line). The results of the former three tests were compared among 14 cases that were culture positive and 156 cases that were culture negative for HSV-1.

RESULTS

The sensitivity of PCR was 100%, while IFA and Giemsa had sensitivities of 85.7% and 57.1% respectively. The specificity of PCR, IFA and Giemsa were found to be 67.9%, 85.3% and 85.9% respectively.

CONCLUSIONS

In the present study, a combination of PCR and immunofluorescence assay appears to be the most suitable choice of tests for diagnosis of HSV-1 keratitis, while detection of MNGC by Giemsa staining procedure may give us a presumptive diagnosis of suspected viral infection.

Applications of the polymerase chain reaction in clinical ophthalmology

Molecular biology has become a valuable component in many areas of medicine, including ophthalmology. Polymerase chain reaction (PCR) is the most widely used tool. It has proven to be a powerful technique in diagnosis and quantification of microorganisms and antibiotic resistance screening. For a growing number of ophthalmic conditions PCR testing can be conducted. It is therefore important that clinicians be knowledgeable about the indications, strengths, and limitations of the technique. The purpose of this review is to explore the current role of PCR in the diagnosis and management of eye disease.

The relationship of graft survival and herpes simplex virus latency in recipient corneal buttons

PURPOSE

To demonstrate relationship between herpes simplex virus (HSV) corneal latency and graft survival.

METHODS

Prospective case control study. 28 recipient corneal buttons and donor cornea-scleral remnants were examined for HSV DNA with polymerase chain reaction (PCR). None of the recipient had a history of HSV infection. Serum samples of graft recipients were analyzed for the presence of anti-HSV IgG and IgM with enzyme-linked immunosorbent assay technique. All corneas were free of stromal scarring or epithelial defect before sampling and had an endothelial cell density of >2000 cells/mm(2).

RESULTS

In twenty three patients (82%) anti-HSV IgG was detected in serum. In none of the recipients anti-HSV IgM was positive. HSV DNA was positive in six out of twenty eight (21%) of the recipient corneal buttons and none of the donor cornea-scleral remnants. In eighteen-months follow-up period three out of six (50%) HSV DNA positive and one out of twenty-two (4.5%) HSV DNA negative patients experienced late endothelial failure that was statistically significantly different (p = 0.022).

CONCLUSION

Even without a history of HSV keratitis, presence of latent HSV virus in recipient cornea is an important risk factor for subsequent graft survival.

Specific antibody production in herpes keratitis: intraocular inflammation and corneal neovascularisation as predicting factors

PURPOSE

The purpose of the study is to investigate whether analysis of specific antibody synthesis can aid the diagnosis of herpes keratitis.

METHODS

Aqueous humor was collected from 39 patients with presumed recurrent herpes keratitis, including 23 consulting for keratitis and 16 patients scheduled for penetrating keratoplasty. Local antibody production was ascertained by analysis of paired aqueous humor/serum samples, using a modified micro-ELISA technique.

RESULTS

Local production of antibodies was found in 32 patients (82%): anti-herpes simplex virus (HSV) antibodies in 26 (67%) and anti-varicella zoster virus (VZV) antibodies in 11 (28%). Twenty of 23 patients with active keratitis (87%), and 12 of 16 undergoing keratoplasty (75%), tested positive. Five patients had local production of both anti-HSV and anti-VZV antibodies, whereas seven patients tested negative. Local antibody production was significantly associated with intraocular inflammation (P<0.05), corneal neovascularisation (P<0.05), and positive response to anti-viral treatment (P<0.05). No complications were encountered in sampling aqueous humor.

CONCLUSIONS

Assessment of local anti-HSV and -VZV antibody production is a safe and reliable diagnostic procedure for recurrent herpes keratitis. It might be particularly helpful in patients presenting with intraocular inflammation and neovascularisation since it discriminates between herpes and non-herpes pathologies and may therefore be useful for preventive and therapeutic strategies.

[Clinical and diagnostic developments in corneal herpes]

The indications for keratoplasty in treating herpes keratitis are currently declining because of recent progress in diagnosis and treatment. Clinically, corneal signs may be caused by HSV reactivation or a secondary anti-HSV immune response. Corneal opacification may be acute or the expression of sequela (meta-herpetic keratitis). The virus can be detected on a corneal surface sample by direct examination or cell culture, the only way to detect an infective virus. The detection of local antibody production in the aqueous humor is an inexpensive method, indicating the local immune anti-HSV response. Detection of HSV DNA using PCR is more sensitive, but the presence of HSV DNA within corneal tIssue may be more delicate to interpret. It is now proven that HSV can be transmitted through a corneal graft from donor to recipient, but no diagnostic test currently detects potentially infective corneas in eyebanks.

New onset of herpes simplex virus epithelial keratitis after penetrating keratoplasty

PURPOSE

To report a series of patients with no previous history of herpes simplex virus (HSV) infection who had new onset of herpetic keratitis after penetrating keratoplasty (PK).

DESIGN

Noncontrolled, retrospective case series.

METHODS

We included in the study the patients who had new onset of herpetic keratitis after penetrating keratoplasty for corneal diseases unrelated to HSV infection who were seen at the Cornea Service at Wills Eye Hospital (Philadelphia, Pennsylvania) from January 1996 to December 2002. The diagnosis of HSV epithelial keratitis was based on clinical characteristics of either a classic herpetic dendrite, a geographic ulcer, or a nonhealing epithelial defect that responded only to antiviral therapy.

RESULTS

Fourteen patients were included in the study. Eight of these (57%) had presented with a geographic ulcer whereas six patients (43%) had a classic dendrite. The most common primary corneal disease that led to PK was pseudophakic bullous keratopathy (36%), followed by keratoconus (29%), Fuchs dystrophy (21%), and corneal scar unrelated to HSV (14%).

CONCLUSIONS

The ophthalmologist should be aware of the possibility of herpetic keratitis in eyes after PK, even in patients with no previous history of HSV infection.

Herpes simplex virus DNA in corneal transplants: prospective study of 38 recipients

Herpes simplex virus (HSV) infection of the eye can induce epithelial and stromal keratitis and may also lead to postoperative endothelial failure in keratoplasty. Clinical symptoms and/or virus culture of corneal scrapings most frequently provide the basis for diagnosis of ocular HSV infection, and although HSV DNA has been shown to be present in the cornea, its role in success or failure of corneal grafts remains unclear. In this study, a PCR assay was used to detect HSV DNA in corneal buttons of 38 corneal graft recipients and in donor scleral remnants, retaining one-half of each sample for subsequent viral isolation. Recipients were followed up clinically for a period of 6 months after keratoplasty. All recipients but three were found to be HSV seropositive. Eight recipient corneal buttons contained detectable HSV DNA (7 HSV-1, 1 HSV-2, the latter case confirmed by viral culture). Two donor corneas were found positive for HSV-1 DNA, with negative cultures, and endothelial graft failure occurred in one of the matching recipients after 4 months. One recipient with no history of herpes contracted herpetic keratitis 4 months after keratoplasty, even though the corneal button and donor scleral remnants contained no detectable HSV DNA. The study confirms previous observations of HSV DNA in the corneal tissue of HSV seropositive patients apparently unrelated to any clinical manifestation of herpes infection. However, as demonstrated by culture, HSV remains infectious and may therefore induce donor-to-host infection in corneal recipients.

HSV-1 antigens and DNA in the corneal explant buttons of patients with non-herpetic or clinically atypical herpetic stromal keratitis

BACKGROUND

Little is known about the role of HSV-1 in keratitis not primarily attributed to herpetic origin. This study therefore aimed to prospectively evaluate the corneal explant buttons of patients with non-herpetic or clinically atypical herpetic stromal keratitis (experimental group: non-HSK) for the presence of HSV-1 antigens and DNA, and to compare the findings with those from individuals with typical herpetic stromal keratitis (positive control group: HSK) or non-inflammatory degenerative keratopathy (negative control group).

METHODS

Corneal buttons derived from 51 patients with HSK, from 72 with non-HSK and from 30 with degenerative keratopathy were prospectively collected and subjected to immunohistochemical analysis for HSV-1 antigens and to HSV-1 DNA amplification.

RESULTS

In corneal buttons derived from patients with non-HSK, viral antigens were detected immunohistochemically in 8/72 cases and DNA amplified in 16/72. Corresponding values for the HSK group were 16/51 and 11/51. Taking viral antigen and DNA findings together, HSV-1 was detected in 18/72 (25%) patients with non-HSK and in 19/51 (37%) with HSK (p=0.2), but in only 2/30 (6%) individuals with non-inflammatory degenerative keratopathy.

CONCLUSION

Since the detection frequencies for HSV-1 antigens and DNA were comparable in the HSK and non-HSK groups, Herpes may play an underestimated and as yet undefined role in non-herpetic and clinically atypical herpetic stromal keratitis, either as a primary trigger of the disease or as a secondary contributor to it. In this category of individuals, early anti-herpetic therapy should be considered if patients do not respond in the expected manner to treatment for non-herpetic stromal keratitis.