Detection of herpesvirus DNA by the polymerase chain reaction (PCR) in vitreous samples from patients with necrotising retinitis

Neutralisation of adeno-associated virus transduction by human vitreous humour

Neutralising antibodies (NAbs), caused by past adeno-associated virus (AAV) infection, represent a critical challenge for AAV-mediated gene therapy, with even low NAb titres capable of inhibiting gene transfer, however in protein-rich environments such as the vitreous it is expected that other constituents could also interact with the transduction process. Inhibition of AAV2/2, AAV2/5, AAV2/6 and AAV2/8 transduction by human vitreous humour (VH) obtained from 80 post-mortem eye cups was investigated in this report, with clinically relevant vitreous dilutions as low as 1:2. Unexpectedly, the highest prevalence of inhibition of transduction was observed against AAV2/6, with 66% of tested samples displaying neutralisation at a 1:2 VH dilution. Only two samples showed inhibition of AAV2/8, indicating this serotype is an attractive vector for use in non-vitrectomised eyes of unscreened individuals. Levels of anti-AAV NAbs observed in the VH were much lower than previously observed in serum of a similar Australian population. Among ten tested eye cup pairs, we observed only small variation in anti-AAV NAbs levels between the left and right eye cups. Interaction with 1:2 diluted VH had an augmentation effect on AAV2/8 transduction (p = 0.004), a phenomenon which was not due to albumin or transferrin and which, if developed, might benefit the use of AAV2/8 in clinical settings.

Polymerase chain reaction analysis of aqueous humor specimens in the diagnosis of cytomegalovirus retinitis in AIDS patients

PURPOSE

To determine the value of the polymerase chain reaction analysis of aqueous humor specimens as a tool to diagnose cytomegalovirus retinitis in AIDS patients.

METHODS

In all, 63 AIDS patients were evaluated in this study. They were sorted into two diagnostic categories: eyes with active cytomegalovirus retinitis and eyes without active cytomegalovirus retinitis. The aqueous humor and blood samples were collected and analyzed by polymerase chain reaction.

RESULTS

A total of 49 patients had active cytomegalovirus retinitis (77.8%) and 14 patients had inactive cytomegalovirus retinitis or normal fundus (22.2%). The mean average of patients was 39 years (range: 22-59). The majority of patients were male (90.5%). Cytomegalovirus DNA was detected in 46 and 7 of 49 aqueous and blood samples, respectively, from AIDS patients with active cytomegalovirus retinitis. We did not detect cytomegalovirus DNA in any of the eyes without active cytomegalovirus retinitis. The sensitivity of polymerase chain reaction in the detection of cytomegalovirus in aqueous humor and blood samples was 93.5% and 14.3%, respectively.

CONCLUSIONS

The polymerase chain reaction analysis is a safe, highly specific, and sensitive method to diagnose cytomegalovirus retinitis.

Evaluation of microbiota associated with Herpesviruses in active sites of generalized aggressive periodontitis

Aims

The present study aimed to investigate microbial patterns associated with disease progression and coinfection by different Herpesviruses in generalized aggressive periodontitis (GAP).

Methods

Microbiological samples were obtained from active (AS) and non-active (n-AS) sites in 165 subjects affected by GAP and were analyzed for 40 bacterial species by the Checkerboard DNA-DNA Hybridization technique and for Herpes simplex 1 (HSV-1), Human Cytomegalovirus (CMV), and Epstein Bar virus (EBV) by PCR.Common Factor Analysis and Multiple Regression Analysis were applied to disclose specific microbial patterns associated with the three viruses.

Results

Herpesviruses were detected in 37.6% of subjects. Detection of each of the searched viruses was associated with specific patterns of subgingival biofilm in AS. Logistic regression analyses evidenced several virus/bacteria associations: i) EBV with Aggregatibacter actinomycetemcomitans; ii) CMV with A. actinomycetemcomitans, Veillonella parvula, Parvimonas micra and Fusobacterium nucleatum subsp. polymorphum; iii) HSV-1 with Porphyromonas gingivalis, Tannerella forsythia, Fusobacterium periodonticum and Staphylococcus aureus.

Conclusions

Microbiological data suggest that Herpesviruses are probably not mere spectators of disease progression and that specific patterns of subgingival plaque are correlated with the presence of different Herpesviruses.

Defense against HSV-1 in a murine model is mediated by iNOS and orchestrated by the activation of TLR2 and TLR9 in trigeminal ganglia

Background

Herpes simplex 1 (HSV-1) causes various human clinical manifestations, ranging from simple cold sores to encephalitis. Innate immune cells recognize pathogens through Toll-like receptors (TLRs), thus initiating the immune response. Previously, we demonstrated that the immune response against HSV-1 is dependent on TLR2 and TLR9 expression and on IFN gamma production in the trigeminal ganglia (TG) of infected mice. In this work, we further investigated the cells, molecules, and mechanisms of HSV-1 infection control, especially those that are TLR-dependent.

Methods

C57BL/6 wild-type (WT), TLR2^−/−, TLR9^−/−, and TLR2/9^−/− mice were intranasally infected with HSV-1. On the viral peak day, the TG and brains were collected from mice and TLR expression was measured in the TG and brain and inducible nitric oxide synthase (iNOS) expression was measured in the TG by real-time PCR. Immunofluorescence assays were performed in mice TG to detect iNOS production by F4/80⁺ cells. Intraperitoneal macrophages nitric oxide (NO) production was evaluated by the Griess assay. WT, CD8^−/−, RAG^−/−, and iNOS^−/− mice were intranasally infected in a survival assay, and their cytokine expression was measured in the TG by real-time PCR.

Results

Infected WT mice exhibited significantly increased TLR expression, compared with their respective controls, in the TG but not in the brain. TLR-deficient mice had moderately increased TLR expression in the TG and brain in compare with the non-infected animals. iNOS expression in the WT infected mice TG was higher than in the other groups with increased production by macrophages in the WT infected mice, which did not occur in the TLR2/9^−/− mice. Additionally, the intraperitoneal macrophages of the WT mice had a higher production of NO compared with those of the TLR-deficient mice. The CD8^−/−, RAG^−/−, and iNOS^−/− mice had 100% mortality after the HSV-1 infection compared with 10% of the WT mice. Cytokines were overexpressed in the iNOS^−/− infected mice, while the RAG^−/− mice were nearly unresponsive to the virus.

Conclusion

TLRs efficiently orchestrate the innate immune cells, eliciting macrophage response (with NO production by the macrophages), thereby controlling the HSV-1 infection through the immune response in the TG of mice.

Absence of CCR5 increases neutrophil recruitment in severe herpetic encephalitis

Background

The neuroinflammatory response aimed at clearance of herpes simplex virus-1 (HSV-1) plays a key role in the pathogenesis of neuroaxonal damage in herpetic encephalitis. Leukocytes activated in an adaptive immune response access brain tissue by passing through the blood–brain barrier. The chemokine CCL5/RANTES is involved in recruitment of these cells to the brain acting via the receptors CCR1, CCR3 and mainly CCR5. Here, we evaluated the role of CCR5 on traffic of leukocytes in the brain microvasculature, cellular and cytokines profile in a severe form of herpetic encephalitis.

Results

Wild type and mice lacking CCR5 (CCR5^-/-) were inoculated intracerebrally with 10⁴ PFU of neurotropic HSV-1. We evaluated the traffic of leukocytes in the brain microvasculature using intravital microscopy and the profile of cytokines by Enzyme-Linked Immunosorbent Assay at 1 day post infection. Flow cytometry and histopathological analyses were also carried out in brain tissue. Absence of CCR5 leads to lower viral load and an increased leukocyte adhesion in brain microvasculature, predominantly of neutrophils (CD11⁺ Ly6G⁺ cells). Moreover, there was a significant increase in the levels of MIP-1/CCL2, RANTES/CCL5, KC/CXCL1 and MIG/CXCL9 in the brain of infected CCR5^-/- mice.

Conclusions

These results suggest that the absence of CCR5 may boost the immune response with a high neutrophil recruitment which most likely helps in viral clearance. Nonetheless, the elevated immune response may be detrimental to the host.

Role of IL-4 in an experimental model of encephalitis induced by intracranial inoculation of herpes simplex virus-1 (HSV-1)

Herpes simplex virus-1 (HSV-1) is a pathogen that may cause severe encephalitis in humans. In this study, we aimed to investigate the role of interleukin-4 (IL-4) in a model of HSV-1 brain infection. IL-4 knockout (IL-4-/-) and wild type (WT) C57BL/6 mice were inoculated with 10(4) plaque-forming units of HSV-1 by the intracranial route. Histopathologic analysis revealed a distinct profile of infiltrating cells at 3 days post-infection (dpi). Infected WT mice presented mononuclear inflammatory cells while IL-4-/- mice developed meningoencephalitis with predominance of neutrophils. IL-4-/- mice had diminished leukocyte adhesion at 3 dpi when compared to infected WT animals in intravital microscopy study. Conversely no differences were found in cerebral levels of CXCL1, CXCL9, CCL3, CCL5 and TNF-α between WT and IL-4-/- infected mice. IL-4 may play a role in the recruitment of cells into central nervous system in this acute model of severe encephalitis caused by HSV-1.

Serpiginous choroiditis in a herpes-positive patient

BACKGROUND

Viruses are one of the most common causes of infections involving the posterior segment of the eye. Viral infections can be congenital or acquired and can affect the retina, choroid, or optic nerve. Herpes simplex virus has been implicated in a number of posterior segment conditions, including serpiginous choroiditis (SC), which has generally been described as idiopathic.

CASE REPORT

A 57-year-old black female presented with decreased and distorted vision in both eyes, of 10 months duration. Funduscopy revealed radial, deep grayish lesions emanating off of the optic disc in a peripapillary fashion. The clinical appearance was suggestive of SC, which was confirmed by fluorescein angiography. Serologic testing was positive for herpes simplex virus and thus may suggest a causative link between the virus and the choroiditis.

CONCLUSIONS

SC has been historically cited as an idiopathic process. There have been only rare reports linking this process with a viral etiology. Laboratory testing and clinical work-up needs to be obtained in any patient suspected of having SC, to detect a viral etiology. Treatment of an underlying condition may lead to optimum resolution in these patients.

PCR detection of multiple human herpesvirus DNA in saliva from HIV-infected individuals in Teresina, State of Piauí, Brazil

INTRODUCTION: Human herpesviruses are frequently associated with orofacial diseases in humans (HSV-1, EBV, CMV and HHV-8), some can also cause systemic disease (CMV and HHV-8). The transmission of these viruses occurs by contact with infected secretions, especially saliva. Human immunodeficiency virus infection is associated with an increased risk of HHVs and related diseases. METHODS: This work aimed to detect HSV-1, EBV, CMV and HHV-8 DNA in saliva of HIV-infected patients from Teresina, northeast Brazil, by PCR and compare these findings with age and sex matched HIV-seronegative individuals. RESULTS: No difference in prevalence was verified between HHV detection in the saliva of HIV-seropositive individuals and controls. The individual frequencies of these viruses in these two populations were different. HIV seropositivity correlated positively with the presence of CMV (OR: 18.2, p= 0.00032) and EBV (OR: 3.44, p= 0.0081). No association between CD4 counts and the prevalence of HHVs in the saliva was observed; however, a strong association was determined between seropositivity and the presence of multiple HHV DNAs in saliva (OR: 4.83, p = 0.0028). CONCLUSIONS: These findings suggest the asymptomatic salivary shedding of HHVs is a common event between HIV-seropositive and seronegative individuals from Teresina, Piauí, Brazil, and, especially for HIV-seropositive patients, saliva is a risk factor for the acquisition/transmission of multiple HHVs.

Toll-like receptor (TLR) 2 and TLR9 expressed in trigeminal ganglia are critical to viral control during herpes simplex virus 1 infection

Herpes simplex virus 1 (HSV-1) is a neurotropic DNA virus that is responsible for several clinical manifestations in humans, including encephalitis. HSV-1 triggers toll-like receptors (TLRs), which elicit cytokine production. Viral multiplication and cytokine expression in C57BL/6 wild-type (WT) mice infected with HSV-1 were evaluated. Virus was found in the trigeminal ganglia (TG), but not in the brains of animals without signs of encephalitis, between 2 and 6 days postinfection (d.p.i.). Cytokine expression in the TG peaked at 5 d.p.i. TLR9-/- and TLR2/9-/- mice were more susceptible to the virus, with 60% and 100% mortality, respectively, as opposed to 10% in the WT and TLR2-/- mice. Increased levels of both CXCL10/IP-10 and CCL2/MCP-1, as well as reduced levels of interferon-γ and interleukin 1-β transcripts, measured in both the TG and brains at 5 d.p.i., and the presence of virus in the brain were correlated with total mortality in TLR2/9-/- mice. Cytokine alterations in TLR2/9-/- mice coincided with histopathological changes in their brains, which did not occur in WT and TLR2-/- mice and occurred only slightly in TLR9-/- mouse brain. Increased cellularity, macrophages, CD8 T cells producing interferon-γ, and expression levels of TLR2 and TLR9 were detected in the TG of WT-infected mice. We hypothesize that HSV-1 infection is controlled by TLR-dependent immune responses in the TG, which prevent HSV-1 encephalitis.

Traffic of leukocytes in the central nervous system is associated with chemokine up-regulation in a severe model of herpes simplex encephalitis: an intravital microscopy study

Herpes simplex virus type 1 (HSV-1) is a human pathogen that may cause severe encephalitis. The development of experimental models of HSV-1 encephalitis is relevant for the comprehension of the immune mechanisms involved in this infection. C57BL/6 mice were inoculated intracranially with 10(4) PFU of neurotropic HSV-1. All animals developed signs of encephalitis and died until day 6 post-infection (pi). Using intravital microscopy, we demonstrated increased leukocyte rolling and adhesion in the brain microvasculature of infected mice at days 1, 3 and 5 pi. The infection was followed by a significant increase in chemokine levels, including CCL2, CCL3, CCL5, CXCL1 and CXCL9. TNF-alpha also showed a significant increase at day 3 pi. Histological analyses demonstrated diffuse meningoencephalitis characterized mainly by mononuclear cell infiltrates. The present model of HSV-1 encephalitis exhibits high mortality in the very first days of infection. Accordingly, there were increased rolling and adhesion of leukocytes along the brain endothelium wall and a high expression of chemokines in the central nervous system. These results corroborate the role of chemokines in leukocyte recruitment following HSV-1 infection in the central nervous system.

The diagnostic yield of vitrectomy specimen analysis in chronic idiopathic endogenous uveitis

PURPOSE

The low diagnostic yield of vitrectomy specimen analysis in chronic idiopathic uveitis (CIU) has been related to the complex nature of the underlying disease and to methodologic and tissue immanent factors in older studies. In an attempt to evaluate the impact of recently acquired analytic methods, the authors assessed the current diagnostic yield in CIU.

METHODS

Retrospective analysis of consecutive vitrectomy specimens from patients with chronic endogenous uveitis (n = 56) in whom extensive systemic workup had not revealed a specific diagnosis (idiopathic) and medical treatment had not resulted in a satisfying clinical situation. Patients with acute postoperative endophthalmitis served a basis for methodologic comparison (Group 2; n = 21).

RESULTS

In CIU, a specific diagnosis provided in 17.9% and a specific diagnosis excluded in 21.4%. In 60.7% the laboratory investigations were inconclusive. In postoperative endophthalmitis, microbiological culture established the infectious agent in 47.6%. In six of eight randomly selected cases, eubacterial PCR identified bacterial DNA confirming the culture results in three, remaining negative in two with a positive culture and being positive in three no growth specimens. A double negative result never occurred, suggesting a very high detection rate, when both tests were applied.

CONCLUSIONS

The diagnostic yield of vitrectomy specimen analysis has not been improved by currently routinely applied methods in recent years in contrast to the significantly improved sensitivity of combined standardized culture and PCR analysis in endophthalmitis. Consequently, the low diagnostic yield in CIU has to be attributed to insufficient understanding of the underlying pathophysiologic mechanisms.

Lethal encephalitis in myeloid differentiation factor 88-deficient mice infected with herpes simplex virus 1

Herpes simplex virus 1 (HSV-1), a large DNA virus from the Herpesviridae family, is the major cause of sporadic lethal encephalitis and blindness in humans. Recent studies have shown the importance of Toll-like receptors (TLRs) in the immune response to HSV-1 infection. Myeloid differentiation factor 88 (MyD88) is a critical adaptor protein that is downstream to mediated TLR activation and is essential for the production of inflammatory cytokines. Here, we studied the relationship between MyD88 and HSV-1 using a purified HSV-1 isolated from a natural oral recurrent human infection. We observed the activation of TLR-2 by HSV-1 in vitro using Chinese hamster ovary cells stably transfected with a reporter gene. Interestingly, we found that only peritoneal macrophages from MyD88-/- mice, but not macrophages from TRL2-/- or from wild-type mice, were unable to produce tumor necrosis factor-alpha in response to HSV-1 exposure. Additionally, although TLR2-/- mice showed no enhanced susceptibility to intranasal infection with HSV-1, MyD88-/- mice were highly susceptible to infection and displayed viral migration to the brain, severe neuropathological signs of encephalitis, and 100% mortality by day 10 after infection. Together, our results suggest that innate resistance to HSV-1 is mediated by MyD88 and may rely on activation of multiple TLRs.

Ocular association of HIV infection in the era of highly active antiretroviral therapy and the global perspective

Ocular involvement is a common complication of HIV infection. Since the late 1990s, widespread use of highly active antiretroviral therapy (HAART) has altered the spectrum, and reduced the incidence of ocular involvement in developed countries. The incidence of the most common ocular opportunistic infection, cytomegalovirus retinitis, has decreased tremendously. However, immune recovery uveitis secondary to HAART has emerged as a frequent visually threatening condition. Early diagnosis and treatment with periocular steroids is helpful in minimizing visual loss. Clinicians should also be aware that certain antimicrobial agents used to treat opportunistic infections in HIV-positive patients are associated with potentially serious ocular side effects. In developing countries, where most of the world's 40 million HIV-positive patients live, the spectrum and incidence of ocular involvement differ from those in developed countries. The lack of HAART availability is among the many causes of these differences, which may include nutritional factors, basic medical care availability and the levels of exposure to different infectious agents. These factors add to the already challenging task of treating ocular complications and preventing blindness in HIV-positive patients in developing countries.

Presumed CMV associated necrotizing retinopathyin a non-HIV immunocompromised host

Herpetic necrotizing retinitis is caused by the herpesvirus group of viruses, including cytomegalovirus (CMV). Reports defining causative viruses have shown CMV to be a rare cause of acute retinal necrosis. In fact, there is only one report in the literature of CMV associated with progressive outer retinal necrosis, which is most commonly associated with Varicella zoster virus. A case is presented of CMV-related necrotizing retinopathy concurrent with subtle signs of herpetic retinitis in an immunocompromised patient, highlighting the spectrum of response of herpetic retinopathies.

Nouveaux concepts étiologiques dans l’uvéite

Uveitis remains an important cause of visual impairment, particularly in young patients. Idiopathic forms of intraocular inflammation should no longer be regarded as a presumed clinical entity, and the ophthalmologist must reconsider the specific etiology of primary uveitis when the clinical examination does not yield a definitive diagnosis or when the course of the disease on corticosteroids remains atypical. Laboratory tests based on serum analysis have limited value and should not be considered as diagnostic proof in different clinical presentations. The diagnostic management of infectious uveitis has been greatly improved by the use of molecular techniques applied to ocular fluids and tissues. Polymerase chain reaction (PCR) technology is a powerful tool that should be proposed in atypical cases of uveitis or retinitis of unclear but potentially infectious origin. This strategy is a major step before using unconventional and new immunomodulatory agents such as anti-TNF-alpha molecules. Under strict experimental conditions including adequate testing to rule out a possible contamination, PCR and its variants have changed our practical approach to intraocular inflammatory disorders and have provided new details for the understanding of infectious uveitis. The concept of pathogen-induced intraocular inflammation can be revisited in the light of molecular data obtained after anterior chamber paracentesis or diagnostic vitrectomy.

Failure to Detect Hepatitis B Virus in Vitreous by Polymerase Chain Reaction

PURPOSE

To assay the vitreous of asymptomatic hepatitis B virus (HBV) carriers for the presence of HBV DNA using polymerase chain reaction (PCR).

METHODS

Vitreous and serum specimens were collected from 13 carriers of HBV. The presence of HBV DNA was investigated by using PCR and Digene's Hybrid Capture System. The presence of hepatitis B surface antigen (HBsAg) in vitreous was also investigated by using the enzyme immunoassay (EIA).

RESULTS

The serum was positive for HBV DNA in3 of the 13 asymptomatic carriers using PCR. Vitreous samples of all the patients, including 3 patients who were positive for HBV DNA in serum, were negative for HBV DNA with PCR and were negative for HBsAg with EIA.

CONCLUSION

There is no evidence of HBV in the vitreous of asymptomatic HBV carriers.

Les uvéites virales

Viral eye diseases are common and associated with different well-known forms of uveitis. However, experimental models and clinical observations have led to an infectious, in particular a viral etiology in different autoimmune conditions. The use of molecular techniques is particularly informative, not only to characterize the previously well-known subgroup of presumed viral uveitis, but also to define the role of these agents or emerging viruses in atypical forms of autoimmune uveitis resistant to conventional therapy. PCR detection of viral DNA in patients with uveitis is a rapid, sensitive and accurate procedure. Therefore, aqueous humor could be analyzed when uveitis is unresponsive to anti-inflammatory molecules, in order to exclude a viral condition and dramatically modify the therapeutic management. Several new viral entities have recently been identified such as cytomegalovirus-associated chronic anterior uveitis and non-necrotizing herpetic retinopathies in immunocompetent hosts. Systemic antiviral drugs should be proposed rapidly in order to control viral replication before the use of corticosteroids. Maintenance therapy based on low-dose antivirals can reduce the rate of recurrence and should be considered.

Prise en charge diagnostique et thérapeutique des rétinites nécrosantes herpétiques

PURPOSE

To study the viral cause and present the management of necrotizing herpetic retinopathies.

METHODS

Charts of patients presenting with acute retinal necrosis (ARN) or progressive outer retinal necrosis (PORN) diagnosed between March 1997 and June 2001 were retrospectively reviewed. Intraocular specimens were obtained in 33 cases to determine the viral cause using polymerase chain reaction-based assays and/or detection of intraocular antibody production.

RESULTS

The mean age was 43.4 Years. Herpesvirus genome was identified in 29 patients (80.5%). In the ARN group (32 patients, 38 eyes), herpes simplex virus (HSV) DNA was found in 11 patients (34.4%), varicella-zoster virus (VZV) in nine patients (28.1%), and cytomegalovirus (CMV) in four patients (12.5%). One patient (3.1%) presented an Epstein-Barr virus (EBV) infection. ARN was bilateral at initial examination in six patients and secondary bilateralization was observed in four patients. In the PORN group (four patients, eight eyes), the retinitis was bilateral and VZV DNA was detected in all cases. Two patients were treated with intravenous acyclovir, six with foscarnet alone, ten with intravenous foscarnet + acyclovir, 18 with intravenous foscarnet and intravitreous ganciclovir injections. Complications of necrotizing herpetic retinitis were cataract (26%), optic nerve atrophy (23.9%), and retinal detachment (17.4%). Final visual acuity was less or equal to 20/200 in 47.8% of cases.

CONCLUSIONS

It is important to determine the specific viral etiology since progression and prognosis may be different in herpetic necrotizing retinitis caused by HSV, VZV, or CMV. Visual prognosis is improved by intensive antiviral therapy, but remains poor if complications occur.

PCR with the aqueous humor, blood leukocytes and vitreous of patients affected by cytomegalovirus retinitis and immune recovery uveitis

PURPOSE

To detect the cytomegalovirus (CMV) genome by PCR in the aqueous humor, blood leukocytes and vitreous of patients affected by retinitis and immune recovery uveitis (IRU).

METHODS

A PCR for CMV genome detection was carried out with the aqueous humor, vitreous and blood leukocytes of 54 patients with retinitis, including 25 HIV-infected patients presenting CMV retinitis in different stages (active lesion 6 cases, healed lesion 14 cases and IRU 5 cases), and 29 non-HIV-infected patients (retinitis unrelated to CMV) as negative controls.

RESULTS

The CMV genome was detected in the vitreous, aqueous humor and blood leukocytes of 3 out of 6 HIV-infected patients, presenting active lesions in the retina. No CMV genome was detected in the vitreous, aqueous humor and blood leukocytes of the 5 HIV-infected patients presenting IRU.

CONCLUSIONS

CMV genome detection by PCR in aqueous humor could be used as a specific and highly predictive technique for confirmation of this infection in the retina. The absence of CMV, based on the results of PCR done in clinical samples of the 5 IRU cases, does not confirm the hypothesis of a viral replication in the vitreous body and aqueous humor of these patients.

Acute retinal necrosis six years after herpes simplex encephalitis: An elusive immune deficit suggested by insufficient test sensitivity

A patient presented with acute retinal necrosis of the left eye. Demonstration of herpes simplex virus (HSV) DNA in the aqueous humour confirmed the diagnosis. Negative results of HSV type-specific antibody tests based on gG antigens suggested a primary HSV infection. However, the patient had a past history of laboratory-confirmed herpes simplex encephalitis 6 years ago. Using antibody tests based on whole viral lysate antigens, he was seropositive from the onset, and immunoblot testing confirmed a lack of anti-gG reactivity. To be able to assess whether this might be related to the apparent inability of his immune system to suppress clinically symptomatic HSV infection, serial samples were tested by an HSV neutralisation test and a whole-blood flow cytometric assay to determine the frequency of HSV-specific CD4 lymphocytes. However, this did not yield evidence of obvious immunodeficiency; the patient reacted similarly to known positive controls by both assays. Although type-specific HSV serological tests based on gG are generally more specific than those based on whole viral lysate antigens, they have a somewhat lower sensitivity, as a certain percentage of HSV-infected individuals do not develop antibodies against gG, and others may suffer a secondary loss of anti-gG reactivity. Thus there is a risk of missing individual infected patients. Unless this potential problem is recognised, serious consequences might possibly result. We therefore urge virologists and clinicians to exercise great care if highly specific antibody assays based on recombinant proteins are employed.

Nonnecrotizing herpetic retinopathies masquerading as severe posterior uveitis

OBJECTIVE

Aqueous humor analysis can be performed in severe atypical forms of posterior uveitis unresponsive to conventional treatment to exclude a viral infection.

DESIGN

Noncomparative interventional case series.

PARTICIPANTS

Thirty-seven immunocompetent patients seen with corticosteroid-resistant forms of posterior uveitis underwent extensive evaluation, including anterior chamber paracentesis, to rule out a nonnecrotizing viral retinopathy.

INTERVENTION

Aqueous fluid samples were prospectively obtained. Polymerase chain reaction (PCR) and serologic evaluation of intraocular antibody production against herpesviruses were performed by molecular techniques and enzyme-linked immunosorbent assay.

MAIN OUTCOME MEASURES

Polymerase chain reaction and local antibody production for herpes simplex virus types 1 and 2, varicella-zoster virus, cytomegalovirus, and Epstein-Barr virus were determined on aqueous fluid samples.

RESULTS

Viral infection was confirmed in 5 cases (13.5%). Clinical presentation included birdshot-like retinochoroidopathy, occlusive bilateral vasculitis, and cystoid macular edema. An antiviral regimen was initiated in all cases. Inflammation was stabilized, and steroid dosage could be significantly reduced.

CONCLUSIONS

Identification of a viral agent during severe posterior uveitis can dramatically change therapeutic management.

Polymerase chain reaction as a rapid diagnostic tool for therapy of acute retinal necrosis syndrome

Herpesviruses are involved in the pathogenesis of acute retinal necrosis syndrome (ARN). A rapid and accurate diagnosis of herpetic infections is crucial for prompt administration of a specific antiviral therapy. The purpose of this study was to evaluate a polymerase chain reaction (PCR)-based assay to detect herpesvirus DNA in the aqueous humor of clinical samples from ten patients with uveitis and clinical suspicion of ARN. Samples were assayed for herpes simplex virus type 1-2 (HSV 1-2), varicella zoster virus (VZV) and cytomegalovirus (CMV). Clinical suspicion of ARN was confirmed for four patients. Two patients (one with bilateral ARN) tested PCR-positive for VZV DNA and the other two were positive for HSV 1-2 DNA. CMV DNA was not detected in any of the samples, and no sample was positive for DNA from more than one virus. The remaining patients did not show any evidence of herpesvirus DNA in their aqueous samples. Our findings demonstrate that the use of PCR for detecting herpesvirus DNA in aqueous humor of uveitic subjects may be a valuable tool for early diagnosis of acute retinal necrosis syndrome and for timely administration of a suitable therapy.

Polymerase chain reaction analysis of aqueous humour samples in necrotising retinitis

AIM

To evaluate the diagnostic value of polymerase chain reaction (PCR) performed on aqueous humour for the detection of viral DNA in patients with necrotising herpetic retinitis.

METHODS

The clinical features and laboratory results of 22 patients (29 eyes) presenting with necrotising herpetic retinitis between March 1999 and June 2001 were reviewed retrospectively. Aqueous humour was obtained after anterior chamber paracentesis and PCR was performed in all cases.

RESULTS

Viral DNA was detected in the aqueous humour of 19 patients (86.4%). Epstein-Barr virus (EBV) seroconversion was evidenced in one additional patient. In the acute retinal necrosis (ARN) group (n = 19), varicella zoster virus (VZV) DNA was identified in six patients, herpes simplex virus 1 (HSV-1) DNA in two patients, herpes simplex virus 2 (HSV-2) DNA in four patients, and cytomegalovirus (CMV) genome in four patients. In the progressive outer retinal necrosis (PORN) group (n = 3), VZV DNA was detected in all patients. No sample was positive for more than one virus.

CONCLUSIONS

PCR analysis of aqueous humour in patients with clinical features of necrotising viral retinitis can provide specific aetiological orientation and the method appears to be safe and highly sensitive.