Herpesvirus infection of eye and brain in HIV infected patients

Neurological Complications Caused by Human Immunodeficiency Virus (HIV) and Associated Opportunistic Co-infections: A Review on their Diagnosis and Therapeutic Insights

Neurocognitive disorders associated with human immunodeficiency virus (HIV) infected individuals increase the risk of mortality and morbidity that remain a prevalent clinical complication even in the antiretroviral therapy era. It is estimated that a considerable number of people in the HIV community are developing neurological complications at their early stages of infection. The daily lives of people with chronic HIV infections are greatly affected by cognitive declines such as loss of attention, learning, and executive functions, and other adverse conditions like neuronal injury and dementia. It has been found that the entry of HIV into the brain and subsequently crossing the blood-brain barrier (BBB) causes brain cell damage, which is the prerequisite for the development of neurocognitive disorders. Besides the HIV replication in the central nervous system and the adverse effects of antiretroviral therapy on the BBB, a range of opportunistic infections, including viral, bacterial, and parasitic agents, augment the neurological complications in people living with HIV (PLHIV). Given the immuno-compromised state of PLHIV, these co-infections can present a wide range of clinical syndromes with atypical manifestations that pose challenges in diagnosis and clinical management, representing a substantial burden for the public health system. Therefore, the present review narrates the neurological complications triggered by HIV and their diagnosis and treatment options. Moreover, coinfections that are known to cause neurological disorders in HIV infected individuals are highlighted.

Bilateral Retrobulbar Optic Neuritis Caused by Varicella Zoster Virus in a Patient with AIDS

Aims

To report on a case of bilateral retrobulbar optic neuritis in a patient with acquired immune deficiency syndrome (AIDS) caused by varicella-zoster virus (VZV); and to review the literature focusing on: cases reported, epidemiology, pathophysiology, diagnosis and treatment.

Presentation of Case

A 38-year-old woman with AIDS presented with a 10-day history of progressive bilateral visual loss and ocular pain. She had bilateral dilated pupils with no light perception; the fundoscopic examination was normal. Facial herpes zoster lesions appeared on the second day of hospitalization Magnetic resonance imaging (MRI) findings were compatible with a bilateral optic neuritis; the cerebrospinal fluid (CSF) showed pleocytosis, increased proteins and a positive VZV-DNA PCR. She was treated with intravenous acyclovir and corticosteroids and was able, when discharged 2 weeks after admission, to carry out activities of daily living.

Discussion

VZV retrobulbar optic neuritis has previously been reported in 12 patients with AIDS, more than half of the cases had concomitant herpes zoster and an associated retinopathy. A positive VZV-DNA in the CSF is indicative of VZV infection, initial use of intravenous acyclovir is recommended, and the concomitant use of corticosteroids would be a prudent choice; the duration of antiviral therapy remains undefined.

Conclusion

VZV retrobulbar optic neuritis in AIDS patients can occur with or without herpes zoster. It is a sight-threatening infectious and inflammatory process requiring the advice of specialists in infectious diseases, ophthalmology, neurology and viral microbiology.

Infection and upregulation of proinflammatory cytokines in human brain vascular pericytes by human cytomegalovirus

Background

Congenital human cytomegalovirus (HCMV) infections can result in CNS abnormalities in newborn babies including vision loss, mental retardation, motor deficits, seizures, and hearing loss. Brain pericytes play an essential role in the development and function of the blood–brain barrier yet their unique role in HCMV dissemination and neuropathlogy has not been reported.

Methods

Primary human brain vascular pericytes were exposed to a primary clinical isolate of HCMV designated ‘SBCMV’. Infectivity was analyzed by microscopy, immunofluorescence, Western blot, and qRT-PCR. Microarrays were performed to identify proinflammatory cytokines upregulated after SBCMV exposure, and the results validated by real-time quantitative polymerase chain reaction (qPCR) methodology. In situ cytokine expression of pericytes after exposure to HCMV was examined by ELISA and in vivo evidence of HCMV infection of brain pericytes was shown by dual-labeled immunohistochemistry.

Results

HCMV-infected human brain vascular pericytes as evidenced by several markers. Using a clinical isolate of HCMV (SBCMV), microscopy of infected pericytes showed virion production and typical cytomegalic cytopathology. This finding was confirmed by the expression of major immediate early and late virion proteins and by the presence of HCMV mRNA. Brain pericytes were fully permissive for CMV lytic replication after 72 to 96 hours in culture compared to human astrocytes or human brain microvascular endothelial cells (BMVEC). However, temporal transcriptional expression of pp65 virion protein after SBCMV infection was lower than that seen with the HCMV Towne laboratory strain. Using RT-PCR and dual-labeled immunofluorescence, proinflammatory cytokines CXCL8/IL-8, CXCL11/ITAC, and CCL5/Rantes were upregulated in SBCMV-infected cells, as were tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1beta), and interleukin-6 (IL-6). Pericytes exposed to SBCMV elicited higher levels of IL-6 compared to both mock-infected as well as heat-killed virus controls. A 6.6-fold induction of IL-6 and no induction TNF-alpha was observed in SBCMV-infected cell supernatants at 24 hours postinfection. Using archival brain tissue from a patient coinfected with HCMV and HIV, we also found evidence of HCMV infection of pericytes using dual-label immunohistochemistry, as monitored by NG2 proteoglycan staining.

Conclusion

HCMV lytic infection of primary human brain pericytes suggests that pericytes contribute to both virus dissemination in the CNS as well as neuroinflammation.

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.

Nicotine applied by transdermal patch induced HSV-1 reactivation and ocular shedding in latently infected rabbits

The identification of factors involved in herpes virus latency and reactivation is critical to a better understanding of the mechanisms essential to viral neuroinvasiveness and neurovirulence. Recurrent episodes of ocular herpes infections cause irreversible corneal scarring and are the primary cause of loss of vision due to an infectious agent in industrialized countries. In this study, we examined the ability of nicotine, a compound known to be involved in stress-associated immunomodulation and recognized as one of the most frequently used addictive agents, to induce ocular shedding in rabbits latently infected with herpes simplex virus type 1 (HSV-1) strain McKrae. New Zealand white rabbits latently infected with HSV-1 at 3-4 weeks post-inoculation were randomly divided into two groups. The corneas of all rabbits were free of lesions as verified by slit lamp biomicroscopy. One group received nicotine by transdermal patch (21 mg/day) for 20 days and the other group served as the control. Reactivation data were obtained by detection of virus in tear film collected by ocular swabbing performed concurrently with the administration of nicotine. Compilation of data from three separate experiments demonstrated that 16.5% (258/1560) of the swabs taken from rabbits treated with nicotine were positive for virus, compared with 8.3% (53/639) of swabs taken from controls. Rabbits receiving nicotine exhibited a significantly (P < 0.0001) higher rate of ocular shedding than controls. The concentration of nicotine in the serum was determined at various times (0-24 hrs) after new patch replacement. Peak (average) serum level of nicotine was obtained 8 hours after patch replacement and exhibited a broad range of values (0.233 microg/mL-6.21 microg/mL). These results suggest that an initial systemic exposure to nicotine significantly increases HSV-1 reactivation. Further studies are needed to reveal any effects of nicotine dependency and nicotine withdrawal on herpesvirus reactivation.