The diagnostic significance of the polymerase chain reaction and isoelectric focusing in herpes simplex virus encephalitis

Association of HSV reactivation and pro-inflammatory cytokine levels with the severity of stomatitis after BEAM chemotherapy and autologous SCT

BACKGROUND

Stomatitis, including oral mucositis and ulcerations induced by HSV-reactivation are major sources of morbidity after high-dose (HD) chemotherapy and subsequent autologous hematopoietic stem cell transplantation (SCT). While increased synthesis of pro-inflammatory cytokines, such as interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF-α)-as well as reactivation of viral infections have frequently been observed in this setting, data on their association with the severity of mucositis is limited.

MATERIALS AND METHODS

Fifteen patients with Hodgkin's or non-Hodgkin's lymphoma receiving HD conditioning chemotherapy and autologous SCT were assessed with respect to oral pain and severity of stomatitis on day -6, 0, +5 to +7, +13 to +15, and +100. On the same dates, IL-1 and TNF-α were quantified in saliva and screening for a wide range of viral pathogens was carried out by cell culture and PCR and complemented by serological analyses. t Tests were used to assess potential associations between these variables.

RESULTS

All but one patient had a positive HSV IgG titer at baseline. Reactivation as confirmed by HSV PCR was observed in seven patients (50%). There was a significant association between the presence of HSV in saliva samples and severity of stomatitis (t test, p = 0.015). The highest concentration of TNF-α and IL-1 coincided with the maximum intensity of stomatitis, but the association was not significant.

CONCLUSION

We found a significant association between the presence of HSV in saliva samples and severity of stomatitis in patients receiving HD chemotherapy and subsequent autologous SCT. While acyclovir prophylaxis has become standard for patients undergoing allogeneic SCT, this issue has not been sufficiently explored for other chemotherapy regimens. Based on our findings, conduction of a well-powered controlled randomized trial may be warranted.

Antibody reactivity to individual structural proteins of measles virus in the CSF of SSPE and MS patients

BACKGROUND

Chronic progressive disorders of the central nervous system (CNS) impose diagnostic problems, particularly in younger patients. The demonstration of antibodies against measles virus (MV) in the cerebrospinal fluid (CSF) plays a major role in the laboratory diagnosis of subacute sclerosing panencephalitis (SSPE) as well as multiple sclerosis (MS).

OBJECTIVES

Because intrathecally synthesized antibodies against MV can be found in both diseases, it is necessary to establish easy and reliable methods to improve the differential diagnosis.

STUDY DESIGN

Seventy-one paired serum/CSF samples obtained from patients with the diagnosis of SSPE (n = 23), MS (n = 14), or acute postinfectious measles encephalitis (APME, n = 8) have been examined. The reactivity of intrathecally synthesized immunoglobulin to individual recombinant MV structural proteins was assessed using Western blot analysis, ELISA as well as isoelectric focusing (IEF).

RESULTS

All CSF samples obtained from patients suffering from SSPE showed a strong antibody response to MV-nucleocapsid (N) and phosphoprotein (P). Sera from 15 of the 23 SSPE patients were reactive to MV-fusion protein (F). Faint reactivity was obtained against MV-matrix (M) or hemagglutinin protein (H) in the minority of samples (40 and 20%, respectively). CSF samples of MS patients only revealed a clear response to N, and in two cases to F. The other proteins were not recognized in the CSF samples of MS patients. In contrast to SSPE, the IEF of CSF from MS patients revealed only few MV-specific oligoclonal bands. In the CSF samples from APME patients, intrathecal MV antibodies were not detected.

CONCLUSIONS

This study shows that discrimination between SSPE and MS can be achieved in doubtful cases by IEF using MV-N, P and F proteins.

Laboratory diagnosis of central nervous system infections caused by herpesviruses

BACKGROUND

Herpesviruses may be associated with various types of central nervous system (CNS) infections. Herpes simplex encephalitis (HSE) has to be considered one of the most severe diseases. As effective antiviral drugs are available, rapid and reliable diagnosis has become important.

OBJECTIVES

To describe polymerase chain reaction (PCR) and serological methods for the detection of herpesvirus-induced CNS infections by the example of HSE.

STUDY DESIGN

620 cerebrospinal fluid (CSF) and 2400 serum samples from 2700 selected hospitalized patients with clinical suspicion of encephalitis were tested for herpes simplex virus (HSV) as well as varicella-zoster virus (VZV) DNA and HSV-specific antibodies, respectively.

RESULTS

HSV-1 DNA could be detected in eight and HSV-2 in three patients with focal encephalitis. In addition, HSV-2 DNA was found in two newborns with encephalitis and two adults suffered from transverse lumbar myelitis. One VZV DNA-positive patient had developed herpes zoster accompanied by meningoencephalitis, and in the other an encephalitis without cutaneous rash was diagnosed. Intrathecal antibody synthesis could be measured when CSF was cleared from viral DNA.

CONCLUSIONS

The detection of viral DNA by PCR technique has become the "gold standard" method for laboratory diagnosis of herpesvirus infections of CNS. Serodiagnosis may be useful to confirm the diagnosis retrospectively.

Subclinical reactivation of herpes simplex virus type 1 in the oral cavity

Reactivation in the oral cavity either symptomatically (recrudescence) or without symptoms (recurrence) may contribute to the transmission of herpes simplex virus type 1 (HSV-1), especially in critical areas of exposure such as dentistry. In order to measure the frequency of HSV-1 reactivation, nested polymerase chain reaction (PCR) was performed on oral swabs collected from 30 healthy people over a period of 58-161 days. In total 19 of 25 (76%) seropositive people were PCR-positive at least once, 6 of these 19 (32%) had recrudescence and 13 (68%) had only asymptomatic reactivation. Frequencies of additional recurrences were higher in people showing symptomatic reactivation than in those who had only recurrences. Recrudescence is a risk factor for elevated levels of asymptomatic HSV-shedding. In most cases HSV-1 was detected only by nested PCR investigated by early onset of therapy or time span before sampling.

Comparative study between chemiluminescence assay and two different sensitive polymerase chain reactions on the diagnosis of serial herpes simplex virus encephalitis

OBJECTIVE

A prospective study was undertaken on the diagnosis of herpes simplex encephalitis (HSVE) by comparing chemiluminescence assay (CL) and two different sensitive polymerase chain reactions (PCRs).

METHODS

The materials comprised 53 serial CSF samples from 31 patients with acute encephalitis with suspected HSVE. Each CSF was distributed to three independent laboratories to perform quantitative measurements by CL, the low sensitive (single) PCR, and high sensitive (nested) PCR. The CL provided a method of detecting HSV itself and the small fragment with HSV antigenicity which was composed of viral component proteins. The serial CSFs were found retrospectively to comprise 24 samples from 11 patients with HSVE due to HSV1 and 29 samples from 20 patients with non-HSVE.

RESULTS

the CL showed 50 to 48 000 pfu/ml in all samples of HSVE (except one) taken from the 3rd to the 25th day. The low sensitive PCR demonstrated 50 to 47 000 pfu/ml in only six samples of HSVE. The high sensitive PCR disclosed less than 100 to 120 000 copies/ml in 11 samples of HSVE. At the acute stage from the 1st to 7th day, the sensitivities of CL and the high sensitive PCR were 100%, but that of the low sensitive PCR was 75%. The sensitivity of CL was significantly higher than those of both PCRs after the acute stage on the 15th to 32nd day. The specificities and positive predictive values of the three methods were 100%. However, the negative predictive value of CL was significantly higher than that of the low sensitive PCR.

CONCLUSIONS

The sensitivity of CL is equivalent to that of the high sensitive PCR during the acute stage and significantly higher than that of the high sensitive PCR after the acute stage. A clear difference in sensitivity exists between the different PCRs. A combination of the PCR, chemiluminescence assay, and serological antibody diagnosis is currently considered the most effective approach for the clinical diagnosis of HSVE.

[Recurrence of herpes simplex encephalitis]

Herpes simplex encephalitis (HSE) rarely occurs in children, is not easily diagnosed, and has a poor prognosis.

CASE REPORT

We report a pediatric case with a relapse on the 29th day despite conventional acyclovir therapy. As the relapse mechanism is not clearly understood, antiviral and immunosuppressive therapy was administered.

CONCLUSION

This case underlines the importance of clinical examination and the necessity of accurate testing prior stopping antiviral treatment. A better understanding of the relapse mechanism is required in order to propose more efficient treatment.

Use of the polymerase chain reaction in the diagnosis of herpes simplex encephalitis: a decision analysis model

PURPOSE

To evaluate the utility of an assay based on a polymerase chain reaction (PCR) of cerebrospinal fluid in the management of patients with suspected herpes simplex encephalitis.

METHODS

A decision model was constructed and used to compare a PCR-based approach with empiric therapy. Inputs required by the model included the sensitivity (96%) and specificity (99%) of PCR (derived from review of the literature), the prevalence of herpes simplex encephalitis (5%, based on the actual prevalence at Barnes Hospital among patients treated empirically with acyclovir), the outcomes for patients with and without herpes simplex encephalitis (derived from clinical studies of the Collaborative Antiviral Study Group and the actual experience at Barnes Hospital), and the average duration of empiric acyclovir therapy for patients with possible herpes simplex encephalitis (5.3 days based on actual experience at Barnes Hospital).

RESULTS

Using these input values, the decision model predicted better outcomes with empiric therapy. However, low rates of inappropriate discontinuation of empiric therapy in patients with herpes simplex encephalitis or improved diagnosis and outcome resulting from a negative PCR assay result in patients without herpes simplex encephalitis led to better outcomes with the PCR-based approach. The PCR-based approach was associated with 9.2 fewer doses of acyclovir per patient.

CONCLUSION

Based on the decision model using conservative assumptions, a PCR-based approach can yield better outcomes and reduced acyclovir use compared with empiric therapy.

The detection of intrathecal synthesis of anti-herpes simplex IgG antibodies: comparison between an antigen-mediated immunoblotting technique and antibody index calculations. European Union Concerted Action on Virus Meningitis and Encephalitis

The detection of intrathecal antibody synthesis was compared by the calculation of antibody indices (AI) derived from ELISA techniques with the detection of virus-specific oligoclonal IgGs by an antigen-mediated capillary blot technique. Twenty-seven paired serum and cerebrospinal fluid (CSF) samples were examined from 15 immunocompetent patients with herpes simplex virus encephalitis (HSE) diagnosed by PCR on early CSF samples. These techniques were also applied to paired samples from 20 multiple sclerosis (MS) patients, 10 patients with other inflammatory neurological diseases and 10 patients with non inflammatory neurological disorders. There was a good correlation between the results obtained by AI and those obtained by immunoblotting, especially in HSE (2 discordant results out of 27). Discrepancies were more frequent (25%) in MS patients where a "polyspecific" reaction characterized by low affinity antibodies is known to occur. Some of the discrepancies could, in part, be due to serological cross-reaction with varicella zoster virus.

Specific diagnostic methods for herpesvirus infections of the central nervous system: a consensus review by the European Union Concerted Action on Virus Meningitis and Encephalitis

BACKGROUND

Herpesvirus infections of the central nervous system are often severe but are fortunately rare. The incidence of these infections has however, increased in recent years as a consequence of an increase in the number of immune-compromised individuals. New diagnostic procedures have improved our ability to diagnose these infections and herpesviruses may yet be implicated as the cause of further neurological diseases with no known aetiology. Methodological standards for selection and evaluation of patient materials are essential to the provision of reliable diagnosis, yet few studies have addressed this important issue.

OBJECTIVES

To describe and define methodological standards and reference methodology for diagnosis of herpesvirus infections of the CNS.

STUDY DESIGN

Information gathered by literature review.

RESULTS

Only for herpes simplex encephalitis is there sufficient data to allow the definition of reference methodology. Good methodological standards exist but few studies have adhered to these standards. As methods for the detection of specific intrathecal antibody synthesis are well established yet under-used in diagnostic virology, the principle of these measurements is reviewed in some detail.

CONCLUSIONS

Herpesvirus infections of the CNS are of increasing importance. High quality, multi-centre studies are needed to establish the value of the new diagnostic test procedures if further improvement in the diagnostic sensitivity and specificity of these procedures is to be achieved.

The role of laboratory investigation in the diagnosis and management of patients with suspected herpes simplex encephalitis: a consensus report. The EU Concerted Action on Virus Meningitis and Encephalitis

As effective therapies for the treatment of herpes simplex encephalitis (HSE) have become available, the virology laboratory has acquired a role of primary importance in the early diagnosis and clinical management of this condition. Several studies have shown that the polymerase chain reaction (PCR) of CSF for the detection of herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2) DNA provides a reliable method for determining an aetiological diagnosis of HSE. The use of PCR in combination with the detection of a specific intrathecal antibody response to HSV currently represents the most reliable strategy for the diagnosis and monitoring of the treatment of adult patients with HSE. The use of these techniques has also led to the identification of atypical presentations of HSV infections of the nervous system and permits the investigation of patients who develop a relapse of encephalitic illness after an initial episode of HSE. A strategy for the optimal use of the investigative laboratory in the diagnosis of HSE and subsequent management decisions is described.

Suitability and clinical application of a multiplex nested PCR assay for the diagnosis of herpes simplex virus infections

A novel multiplex nested polymerase chain reaction (PCR) assay was designed and evaluated for routine diagnosis of herpes simplex virus (HSV) infections in patients with either putative HSV infection of the central nervous system or suspected HSV keratitis. Single-tube amplification of HSV type 1 (HSV-1) or type 2 (HSV-2) DNA extracted from cerebrospinal fluid (CSF) or from keratectomy specimens was followed by differentiation of the virus type-specific PCR products either by agarose gel analysis or by DNA enzyme immunoassay. Among 417 CSF specimens obtained from 395 consecutive patients with clinically suspected HSV infection, 11 (2.6%) were positive for HSV-1 DNA and four (1.0%) probes were positive for HSV-2 DNA. None of the specimens was positive for both HSV-1 and HSV-2 DNA. The genome of HSV-2 was detected in a CSF sample obtained from a woman with meningoencephalitis and genital herpes. The presence of PCR inhibitors was detected in six of 111 (5.4%) reconstructed CSF samples. Inhibition could be removed following extraction with a commercial kit. HSV-1 DNA, but no HSV-2 DNA, was detected in corneal buttons obtained from patients with suspected herpetic keratitis. No contamination has been recorded during the 2-year routine use of this test, which has met the specific requirements of a diagnostic laboratory.

Detection of both herpes simplex and varicella-zoster viruses in cerebrospinal fluid from patients with encephalitis

Cerebrospinal fluid (CSF) samples from 46 patients with encephalitis were studied for the presence of herpes simplex virus (HSV) types 1 and 2 and/or varicella zoster virus (VZV)-specific DNA sequences by the polymerase chain reaction (PCR) assay. Patients were studied because of detection of intrathecal production of IgG antibody to HSV alone (10 patients, Group A) or to both HSV and VZV (11 patients, Group B) or because of the presence of specific anti-HSV IgG in CSF without evidence of intrathecal antibody production (25 patients, Group C). CSF samples taken between days 1 and 10 from onset of encephalitis were available from all patients, and follow-up samples (taken after 10 days from onset) were obtained from some of them. Positive PCR results were obtained in a total of 13 patients. Four patients (three from Group A and one from Group B) gave amplification of HSV type 1 DNA alone, two patients (both from Group B) showed amplification of VZV DNA alone, and seven patients (all from Group B) gave dual amplification of both HSV type 1 and VZV DNA sequences in CSF. All CSF samples from patients in Group C were negative by PCR. Ten patients with CSF samples positive by PCR lacked a prior history of herpetic cutaneous lesions. In seven patients, serum antibody tests (specific IgM detection and specific IgG avidity assays) identified both primary and recurrent infections. The results suggest that the dual presence of IgG antibody to both HSV and VZV in CSF from patients with encephalitis may reflect in some cases a dual infection of the central nervous system caused by both agents.

Detection of herpes simplex virus DNA in cerebrospinal fluid samples using the polymerase chain reaction and microplate hybridization

As conventional polymerase chain reaction (PCR) procedures are time-consuming and laborious, we developed and evaluated a rapid semi-automatic microplate method to detect the amplified PCR products. The use of PCR, with subsequent hybridization in microplates, is described for the detection of herpes simplex virus (HSV) DNA in cerebrospinal fluid samples. The principle of the method is based on two phases. Firstly, the amplification of the viral DNA in the sample is undertaken using a pair of primers of which one is biotinylated. Secondly, the amplified viral genomic sequences are bound to the wells of streptavidin-coated microplates and hybridized with digoxigenin-labeled oligonucleotide probes which are then detected using anti-digoxigenin antibody enzyme conjugates and either a photometric, fluorometric or luminometric substrate and microplate reader. The method is highly sensitive allowing the detection of as few as five purified DNA molecules. Compared to conventional gel electrophoresis followed by Southern blotting the established microplate hybridization is also much less time-consuming and involves less manual work. The applicability of the method is described for use as a routine diagnostic procedure for detection of early central nervous system infections caused by HSV-1 and HSV-2.

Acute meningo-encephalitis in pregnancy-a problem of differential diagnosis

Two cases of Coxsackie B viral meningo-encephalitis in pregnant women are described. Both patients recovered well and delivered healthy babies, but because of delay in establishing the aetiology of their infections both mothers, and one child, received acyclovir therapy. The differential diagnosis of non-pyogenic meningo-encephalitis in late pregnancy can present particular problems: clinicians caring for such women should remain aware of the potential for enteroviral infection in their patients, and take appropriate action to prevent cross-infection in neonatal units.

HSV and the CNS

Herpes simplex virus encephalitis (HSVE) is an encephalitis with a predelection for the temporal lobes and related structures that is caused by HSV-1 or HSV-2. Because HSV has many properties that would be ideal for a gene transfer vector targeting the nervous system, an understanding of HSVE is of experimental, as well as clinical, importance to neuroscientists. Herpesviruses have a characteristic architecture of the virion. The molecular aspects of HSVE include the consequences of latency and neurovirulence. Studies on neurovirulence have focused on peripheral multiplication of HSV, the invasion of the CNS, and growth in the CNS. The virus appears to gain access to the CNS via the olfactory and trigeminal nerves and, transneuronally, the limbic system. The definition of latency has still to be clarified; in general, latency includes three separable phases: establishment, maintenance, and reactivation. In humans, there exists a large overlap of clinical presentations of patients with HSVE and those of patients with encephalitis of other origin. However, the presence of memory loss, personality changes, and olfactory hallucinations correlate with the limbic and temporal lobe pathology in HSVE and are characteristic. Several factors correlate with poor outcome in patients: age, time of establishment of therapy, and level of consciousness on admission of patients.

Comparison of two hybridization assays for the rapid detection of PCR amplified HSV genome sequences from cerebrospinal fluid

Rapid diagnosis of herpes simplex encephalitis (HSE) can only be achieved by the polymerase chain reaction (PCR). In order to carry out PCR under routine conditions, it is of great importance to establish an easy DNA extraction protocol and especially a rapid and sensitive DNA detection method. In the present study, two different solid phase hybridization assays (Gen-Eti-K-DNA Enzyme Immunoassay (DEIA), Sorin Biomedica, Italy and Enzymun-Test DNA detection, Boehringer Mannheim, Germany) were compared for detection of PCR amplified HSV DNA polymerase genome region, using standard primers, from cerebrospinal fluid (CSF) samples. 122 CSF samples obtained from patients suffering from encephalitis and hospitalized at the University Clinics of Frankfurt and Graz during the period January 1992 to July 1993 were tested. To ascertain the sensitivity of the hybridization assays, dilution series of a plasmid, encoding the amplified region of the polymerase gene, were investigated. The detection limit of the DEIA assay was one copy of the plasmid/microliter, and the lowest amount of DNA which could be detected by the Enzymun assay as well as Southern blot was 10 copies/microliter. 15 CSF samples obtained from patients with HSE were found positive by the three assays. Concordant results were also obtained with CSF samples from non-HSE patients. The results of this study show that new hybridization systems guarantee a fast and high-sensitive detection of amplified HSV DNA. HSV PCR in CSF can be carried out routinely by the combined use of rapid hybridization and a simple extraction procedure.

New non-invasive rapid diagnosis of herpes simplex virus encephalitis by quantitative detection of intrathecal antigen with a chemiluminescence assay

A technique for detecting herpes simplex virus (HSV) antigen in CSF by measuring the antigen-antibody complex-activated complement-stimulated chemiluminescence in normal granulocytes was applied to 17 CSF samples from 10 patients with herpes simplex virus encephalitis (HSVE), and 26 samples from 22 patients with a non-HSVE brain illness. All CSF samples taken from the 5th to the 38th day (including seven from the 5th to the 10th day) of HSVE were positive, whereas those for all non-HSVE samples were negative. This assay required only five hours to yield a result.

Laboratory techniques in the diagnosis of herpes simplex infection

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A polymerase chain reaction assay of cerebrospinal fluid in patients with suspected herpes simplex encephalitis

A polymerase chain reaction (PCR) was used to detect herpes simplex virus (HSV) deoxyribonucleic acid (DNA) in CSF of 109 patients with possible herpes simplex encephalitis. HSV DNA was found in 20/109 patients. In 14 of these patients the diagnosis was confirmed by a rise in CSF antibodies, isolation of HSV from the brain, or both. In 3 patients CSF antibodies did not rise and 3 patients did not have a follow up lumbar puncture or a brain biopsy. In 19/20 patients HSV DNA was present in the first CSF specimen. The virus was identified as HSV I in 15 patients and HSV II in 4; the virus was not typed in the other patient. A possible diagnosis of herpes simplex encephalitis was not confirmed in the 89 PCR-negative patients. HSV DNA was present in CSF of 3 patients who had meningitis with herpetic genital infections but it was not found in 24 patients with other neurological diseases. The results suggest that the detection of HSV DNA in CSF using a PCR assay will be an accurate method of early diagnosis of herpes simplex encephalitis.

Evaluation of the polymerase chain reaction for diagnosis of herpes simplex virus encephalitis

Cerebrospinal fluid samples from 257 patients with suspected herpes simplex virus encephalitis were prospectively analyzed by herpes simplex virus polymerase chain reaction. The polymerase chain reaction indicated herpes simplex virus encephalitis in 9 serologically proven cases and in 14 additional patients. Increased polymerase chain reaction signals were observed together with more severe neurological symptoms (P < 0.01) and within the first days of acyclovir treatment (P < 0.05).