Acyclovir resistant acute herpes simplex encephalitis associated with acute retinal necrosis: A case report and review of the literature

A 55-year-old man was admitted to our hospital for investigation of high fever, decreased consciousness and bilateral visual impairment. His cerebrospinal fluid analysis revealed pleocytosis of mononuclear cells and an increased protein concentration. FLAIR images revealed multiple high-intensity lesions in the frontal lobe, part of which was enhanced with gadolinium. Despite initiating treatment with acyclovir and corticosteroids, his consciousness and visual acuity deteriorated. Immunopathological examination of brain biopsies showed numerous herpes simplex virus type 2-positive neurons and macrophages, leading to a diagnosis of herpes simplex encephalitis (HSE). Fundoscopic examination revealed multiple foci of retinitis with vasculopathies, and inflammation in the anterior chamber and vitreous, indicating acute retinal necrosis (ARN). Foscarnet treatment was initiated in place of acyclovir and his consciousness improved, with a slight improvement in visual acuity. ARN is typically caused by a herpes virus infection limited to the eyeball, and rarely in combination with HSE. In such cases, there is a latency of approximately 2-4 weeks between ARN and the onset of encephalitis. Our case is unique in that HSE and ARN developed simultaneously, and it highlights that there may not always be a latency between the onsets of the two disorders. Finally, foscarnet should be considered in cases of HSE and ARN with acyclovir resistance.

Small interfering RNA targeting for infected-cell polypeptide 4 inhibits herpes simplex virus type 1 replication in retinal pigment epithelial cells

Background:  This study sought to inhibit herpes simplex virus type 1 replication using small interfering RNA which targeting infected‐cell polypeptide 4 genes to mediate transcription of early and late viral genes in herpes simplex virus type 1 lytic (productive) infection in retina epithelial cells.

Methods:  After pre‐ or post‐infecting with herpes simplex virus type 1, small interfering RNAs were transfected into retina epithelial cells. The antiviral effects of small interfering RNA were evaluated by Western blot, plaque assays, indirect immunofluorescence and reverse transcription polymerase chain reaction. The viral titre was detected by the 50% tissue culture infective dose method.

Results:  Small interfering RNA decreased infected‐cell polypeptide 4 expression in retina epithelial cells that were infected with herpes simplex virus type 1 before or after small interfering RNA transfection. Compared with herpes simplex virus type 1 infection alone or transfection with negative control small interfering RNA, the viral titre and the retina epithelial cell cytopathic effect were significantly decreased in retina epithelial cells transfected with infected‐cell polypeptide 4‐targeting small interfering RNA (50 and 100 nM) (P < 0.05). The small interfering RNA effectively silenced herpes simplex virus type 1 infected‐cell polypeptide 4 expression on both mRNA and the protein levels (P < 0.05). The inhibition of infected‐cell polypeptide 4‐targeting small interfering RNA on infected‐cell polypeptide 4 protein expression was also verified by Western blot in herpes simplex virus type 1 infected human cornea epithelial cell, human trabecular meshwork cells and Vero cells.

Conclusions:  Infected‐cell polypeptide 4‐targeting small interfering RNA can inhibit herpes simplex virus type 1 replication in retina epithelial cells, providing a foundation for development of RNA interference as an antiviral therapy.

[Acute retinal necrosis from the virologist's perspective]

Acute retinal necrosis occurs in approximately one per million persons per year and is caused in approximately 70% of the cases by the varicella zoster virus or in about 30% of the cases by herpes simplex virus. The early diagnosis is primarily based on virus-specific polymerase chain reaction in fluid from the anterior chamber or vitreous humor and can be supported by the determination of specific antibody titers from fluid and serum. Virus detection provides the basis for early causative therapy which limits disease progression and risk of complications. Retinal infections by varicella zoster virus or herpes simplex virus are treated with aciclovir, ganciclovir, or famciclovir. Ganciclovir and valganciclovir are used for the therapy of retinal cytomegalovirus infections. In the case of resistance development, foscarnet or cidofovir are available as second line antiviral drugs. The early use of specific antiviral agents is a crucial prerequisite for optimized therapy of acute retinal necrosis.

Role for nectin-1 in herpes simplex virus 1 entry and spread in human retinal pigment epithelial cells

Herpes simplex virus 1 (HSV-1) demonstrates a unique ability to infect a variety of host cell types. Retinal pigment epithelial (RPE) cells form the outermost layer of the retina and provide a potential target for viral invasion and permanent vision impairment. Here we examine the initial cellular and molecular mechanisms that facilitate HSV-1 invasion of human RPE cells. High-resolution confocal microscopy demonstrated initial interaction of green fluorescent protein (GFP)-tagged virions with filopodia-like structures present on cell surfaces. Unidirectional movement of the virions on filopodia to the cell body was detected by live cell imaging of RPE cells, which demonstrated susceptibility to pH-dependent HSV-1 entry and replication. Use of RT-PCR indicated expression of nectin-1, herpes virus entry mediator (HVEM) and 3-O-sulfotransferase-3 (as a surrogate marker for 3-O-sulfated heparan sulfate). HVEM and nectin-1 expression was subsequently verified by flow cytometry. Nectin-1 expression in murine retinal tissue was also demonstrated by immunohistochemistry. Antibodies against nectin-1, but not HVEM, were able to block HSV-1 infection. Similar blocking effects were seen with a small interfering RNA construct specifically directed against nectin-1, which also blocked RPE cell fusion with HSV-1 glycoprotein-expressing Chinese hamster ovary (CHO-K1) cells. Anti-nectin-1 antibodies and F-actin depolymerizers were also successful in blocking the cytoskeletal changes that occur upon HSV-1 entry into cells. Our findings shed new light on the cellular and molecular mechanisms that help the virus to enter the cells of the inner eye.

Acute retinal necrosis as a late sequela of herpes simplex type 1 encephalitis in a child

Herpes simplex virus (HSV) is a common infection that occasionally presents with destructive lesions. Two of the most feared presentations of HSV are encephalitis and acute retinal necrosis. Although there are numerous reports of acute retinal necrosis presenting after HSV-2 infection in children, it has been rarely reported in children after HSV-1 infection. Herein we report a child who developed acute retinal necrosis 17 months after HSV-1 encephalitis.

Acute retinal necrosis features, management, and outcomes

OBJECTIVE

To determine the viral diagnosis and factors affecting the visual outcome of eyes with acute retinal necrosis.

DESIGN

Nonrandomized, retrospective, interventional, noncomparative series.

PARTICIPANTS

A cohort of 22 human immunodeficiency virus-negative patients with acute retinal necrosis (ARN). There were 17 unilateral and 5 bilateral cases.

INTERVENTION

Diagnostic vitreous biopsy for polymerase chain reaction (PCR) viral DNA analysis, prophylactic barrier laser posterior to necrotic retina to try to prevent rhegmatogenous retinal detachment (RD), intravenous acyclovir in combination with oral, and vitrectomy for RD repair.

MAIN OUTCOME MEASURES

Results of PCR viral DNA analysis, relationship between prophylactic barrier argon laser photocoagulation and occurrence of RD, and visual acuities at presentation and follow-up.

RESULTS

Varicella-zoster virus (VZV) was detected in 66.7% (12/18) of eyes (66.7% of patients [10/15]) with vitreous biopsy and herpes simplex virus (HSV) in 22.2% (4/18) of eyes (20% of patients [3/15]). Epstein-Barr virus (EBV) was detected in 16.7% (3/18) of eyes (20% of patients [3/15]), and all the EBV-positive eyes were also positive for VZV. Polymerase chain reaction results were identical in both eyes of bilateral cases (5 patients) and were negative in 11.1% (2/18) of eyes (13.3% of patients [2/15]) biopsied. Systemic corticosteroid treatment given before ARN diagnosis did not appear to increase the risk of developing RD (P = 0.69). Rhegmatogenous RD occurred in 35.3% (6/17) of eyes given prophylactic argon laser treatment and in 80% (8/10) of eyes that could not be lasered prohylactically. Of RDs, 96.3% (13/14) occurred after the third week and up to 5 months from onset of symptoms. The VA after surgical repair of RD improved relative to the presentation acuity in 33.3% (4/12) of eyes.

CONCLUSION

Varicella-zoster virus is the leading cause of ARN. We recommend the management of ARN to include prompt diagnosis; prophylactic argon laser retinopexy, preferably within the first 2 weeks to reduce risk of RD; systemic acyclovir; and corticosteroids to control the severe inflammation associated with ARN. Despite the guarded visual prognosis, RD repair may result in improved visual outcomes.

Herpes simplex encephalitis: adolescents and adults

Herpes simplex encephalitis (HSE) remains one of the most devastating infections of the central nervous system despite available antiviral therapy. Children and adolescents account for approximately one third of all cases of HSE. Clinical diagnosis is suggested in the encephalopathic, febrile patient with focal neurologic signs. However, these clinical findings are not pathognomonic because numerous other diseases in the central nervous system can mimic HSE. Neurodiagnostic evaluation can provide support for the diagnosis by the demonstration of temporal lobe edema/hemorrhage by magnetic resonance image scan and spike and slow-wave activity on electroencephalogram. In the current era, the diagnostic gold standard is the detection of herpes simplex virus (HSV) DNA in the cerebrospinal fluid by polymerase chain reaction (PCR). Although PCR is an excellent test and preferable to brain biopsy, false negatives can occur early after disease onset. Acyclovir is the treatment of choice and is administered at 10 mg/kg every 8 h for 21 days. Even with early administration of therapy after the disease onset, nearly two thirds of survivors have significant residual neurologic deficits. Current investigative efforts are assessing the prognostic value of quantitative PCR detection of viral DNA at the onset of therapy as well as at the completion of therapy and the contribution of prolonged antiviral therapy to improved neurologic outcome.

Herpes simplex: Encephalitis children and adolescents

Herpes simplex encephalitis (HSE) remains one of the most devastating infections of the central nervous system despite available antiviral therapy. Children and adolescents account for approximately one third of all cases of HSE. Clinical diagnosis is suggested in the encephalopathic, febrile patient with focal neurologic signs. However, these clinical findings are not pathognomonic because numerous other infections in the central nervous system can mimic HSE. Support for the diagnosis from a neurodiagnostic perspective is aided by the demonstration of disease of the temporal lobe by magnetic resonance image scan and spike and slow-wave activity on electroencephalogram. In the current era, the gold standard for establishing diagnosis is the detection of herpes simplex virus DNA in the cerebrospinal fluid by polymerase chain reaction (PCR). Although PCR is an excellent test and far more desirable than brain biopsy, false negatives can occur early after disease onset. Current therapeutic management calls for the administration of acyclovir at 10 mg/kg every 8 hours for 21 days. Even with early administration of therapy after the onset of disease, nearly two thirds of survivors will have significant residual neurologic deficits. Recent investigative efforts are assessing the value of PCR detection of viral DNA at the completion of therapy and the value of prolonged antiviral therapy.