Herpesviruses and enteroviruses in infections of the central nervous system: a study using time-resolved fluorometry PCR

Progress in etiological diagnosis of viral meningitis

In recent years, with the rapid development of molecular biology techniques such as polymerase chain reaction and molecular biochip, the etiological diagnosis of viral encephalitis has a very big step forward. At present, the etiological examination of viral meningitis mainly includes virus isolation, serological detection and molecular biological nucleic acid detection. This article reviews the progress in etiological diagnosis of viral meningitis.

HERQ-9 Is a New Multiplex PCR for Differentiation and Quantification of All Nine Human Herpesviruses

By adulthood, almost all humans become infected by at least one herpesvirus (HHV). The maladies inflicted by these microbes extend beyond the initial infection, as they remain inside our cells for life and can reactivate, causing severe diseases. The diagnosis of active infection by these ubiquitous pathogens includes the detection of DNA with sensitive and specific assays. We developed the first quantitative PCR assay (HERQ-9) designed to identify and quantify each of the nine human herpesviruses. The simultaneous detection of HHVs in the same sample is important since they may act together to induce life-threatening conditions. Moreover, the high sensitivity of our method is of extreme value for assessment of the effects of these viruses persisting in our body and their long-term consequences on our health.

Infections with the nine human herpesviruses (HHVs) are globally prevalent and characterized by lifelong persistence. Reactivations can potentially manifest as life-threatening conditions for which the demonstration of viral DNA is essential. In the present study, we developed HERQ-9, a pan-HHV quantitative PCR designed in triplex reactions to differentiate and quantify each of the HHV-DNAs: (i) herpes simplex viruses 1 and 2 and varicella-zoster virus; (ii) Epstein-Barr virus, human cytomegalovirus, and Kaposi’s sarcoma-associated herpesvirus; and (iii) HHV-6A, -6B, and -7. The method was validated with prequantified reference standards as well as with mucocutaneous swabs and cerebrospinal fluid, plasma, and tonsillar tissue samples. Our findings highlight the value of multiplexing in the diagnosis of many unsuspected, yet clinically relevant, herpesviruses. In addition, we report here frequent HHV-DNA co-occurrences in clinical samples, including some previously unknown. HERQ-9 exhibited high specificity and sensitivity (LOD₉₅s of ∼10 to ∼17 copies/reaction), with a dynamic range of 10¹ to 10⁶ copies/μl. Moreover, it performed accurately in the coamplification of both high- and low-abundance targets in the same reaction. In conclusion, we demonstrated that HERQ-9 is suitable for the diagnosis of a plethora of herpesvirus-related diseases. Besides its significance to clinical management, the method is valuable for the assessment of hitherto-unexplored synergistic effects of herpesvirus coinfections. Furthermore, its high sensitivity enables studies on the human virome, often dealing with minute quantities of persisting HHVs.

IMPORTANCE By adulthood, almost all humans become infected by at least one herpesvirus (HHV). The maladies inflicted by these microbes extend beyond the initial infection, as they remain inside our cells for life and can reactivate, causing severe diseases. The diagnosis of active infection by these ubiquitous pathogens includes the detection of DNA with sensitive and specific assays. We developed the first quantitative PCR assay (HERQ-9) designed to identify and quantify each of the nine human herpesviruses. The simultaneous detection of HHVs in the same sample is important since they may act together to induce life-threatening conditions. Moreover, the high sensitivity of our method is of extreme value for assessment of the effects of these viruses persisting in our body and their long-term consequences on our health.

[Etiologic diagnosis in meningitis and encephalitis molecular biology techniques]

INTRODUCTION

The aetiological study of infections of the central nervous system has traditionally been performed using bacterial cultures and, more recently, using polymerase chain reaction (PCR) for herpes simplex virus (HSV). Bacterial cultures may not have good performance, especially in the context of patients who have received antibiotics prior to sampling, and a request for HSV only by PCR reduces the information to only one aetiological agent. The aim of this study is to determine the infectious causes of meningitis and encephalitis, using traditional microbiology and molecular biology to improve the aetiological diagnosis of these diseases.

PATIENTS AND METHOD

A prospective study was conducted on 19 patients with suspected meningitis, admitted to the Luis Calvo Mackenna Hospital in Santiago, Chile, from March 1, 2011 to March 30, 2012. After obtaining informed consent, the CSF samples underwent cytochemical study, conventional culture, multiplex PCR for the major producing bacterial meningitis (N. meningitidis, S. pneumoniae, H. influenzae), real-time single PCR for HSV-1 and 2, VZV, EBV, CMV, HHV-6 and enterovirus. Clinical and epidemiological data were also collected from the clinical records.

RESULTS

Of the 19 patients analysed, 2 were diagnosed by conventional methods and 7 by adding molecular biology (increase to 37%). Three patients had meningitis due to S. pneumoniae, one due to Enterobacter cloacae, 2 patients meningoencephalitis HSV-1, and one VZV meningitis.

CONCLUSIONS

The addition of PCR to conventional diagnostic methods in CNS infections increases the probability of finding the causal agent. This allows a more adequate, timely and rational management of the disease.

Clinical application of viral cerebrospinal fluid PCR testing for diagnosis of central nervous system disorders: a retrospective 11-year experience

The cerebrospinal fluid (CSF) polymerase chain reaction (PCR) is the gold standard to detect cerebral viral activity. As positive findings do not prove an impact on the neurological disorder, data interpretation is difficult. To better assess the impact of positive CSF PCR findings in different neurological diseases and to identify coherences facilitating CSF PCR data interpretation, we performed this retrospective analysis of CSF PCR data of 481 pediatric and 2604 adult patients, including herpes simplex virus (HSV), varicella zoster virus (VZV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), human herpesvirus 6 (HHV-6), and enteroviruses (EV). Nucleic acid of EBV was detected in 1.6% (39/2449), of VZV in 1.3% (34/2624), of HSV in 1.24% (37/2994), of EV in 0.4% (10/2364), of HHV-6 in 0.17% (4/2417), and of CMV in 0.2% (5/2514) of the patients. Newborns and elderly people showed highest infection rates. HSV, VZV, and EV prevailed in typical infectious central nervous system (CNS) diseases; EBV, in further inflammatory neurological diseases; HSV and EBV, in immunocompromised patients; and EBV, HSV, and HHV-6, in further non-inflammatory neurological diseases. Analysis of successive PCR studies revealed delayed viral detection for EBV (6/147) and HSV (1/217), respectively. Rapid viral clearance was typical for HSV, VZV, CMV, and EV infections, although the maximum duration of viral detection was 15days for HSV and 12days for VZV, respectively. This suggests that the detection of HSV, VZV, CMV, and EV strongly indicates symptomatic viral CNS disease. Secondary viral reactivation mostly underlies positive EBV and HHV-6 findings. Their detection does not rule out clinical impact but recommends searching for additional underlying conditions.

Clinical features, outcomes, and cerebrospinal fluid findings in adult patients with central nervous system (CNS) infections caused by varicella-zoster virus: comparison with enterovirus CNS infections

Varicella-zoster virus (VZV) is known to be associated with central nervous system (CNS) infections in adults. However, the clinical characteristics of VZV CNS infections are not well characterized. The aim of this study was to compare the clinical manifestations, outcomes, and cerebrospinal fluid (CSF) findings in patients with VZV CNS infections with those in patients with enterovirus (EV) CNS infections. This retrospective cohort study was performed at a 2,700-bed tertiary care hospital. Using a clinical microbiology computerized database, all adults with CSF PCR results positive for VZV or EV that were treated between January 1999 and February 2013 were identified. Thirty-eight patients with VZV CNS infection and 68 patients with EV CNS infection were included in the study. Compared with the EV group, the median age in the VZV group was higher (VZV, 35 years vs. EV, 31 years; P = 0.02), and showed a bimodal age distribution with peaks in the third and seventh decade. Encephalitis was more commonly encountered in the VZV group (VZV, 23.7% vs. EV, 4.4%; P = 0.01). The median lymphocyte percentage in the CSF (VZV, 81% vs. EV, 36%; P < 0.001) and the CSF protein level (VZV, 100 mg/dl vs. EV, 46 mg/dl; P < 0.001) were higher in the VZV group. Compared with patients with EV CNS infection, patients with VZV CNS infection developed encephalitis more often and exhibited more intense inflammatory reaction. Nevertheless, both VZV and EV CNS infections were associated with excellent long-term prognosis.

Evaluation of multiplex polymerase chain reaction and microarray-based assay for rapid herpesvirus diagnostics

Rapid diagnosis is critical to minimize morbidity and mortality associated with infections of the central nervous system (CNS). In this study, we evaluated the performance of a multiplex polymerase chain reaction (PCR) and microarray-based method, Prove-it™ Herpes, in a routine clinical laboratory setting for the diagnostics of 7 herpesviruses in viral CNS infections. Cerebrospinal fluid samples (n = 495), which had arrived for diagnostics in the 5 participating laboratories, were analyzed for herpesvirus DNA both by the current PCR-based method of the laboratory and by the microarray assay. The sensitivity and specificity for the microarray assay were 93% and 99%, respectively. The microarray assay was considered as a rapid and robust diagnostic platform that was easily implemented into the laboratory workflow. The broad herpesvirus coverage and the small sample volume required by the assay could benefit the diagnostics and thus the treatment of life-threatening infections of the CNS, especially among immunocompromised patients.

Review of the etiologies of viral meningitis and encephalitis in a dengue endemic region

OBJECTIVES

To evaluate the etiology of viral meningitis and encephalitis in adults and adolescents living in areas affected by dengue.

METHODS

Over two years, adults and adolescents with diagnoses of viral encephalitis or meningitis were selected for study in Brazil. PCRs for dengue, enterovirus, HSV1 and 2 and cytomegalovirus were performed in CSF samples. Serum and CSF samples were tested for the presence of anti-dengue IgM antibodies.

RESULTS

The etiologies of encephalitis and meningitis were determined in 70% of cases (30/47). Dengue was the leading cause of encephalitis (47%) with normal CSF cellularity in 75% of these patients. HSV1 was found in 17.6% of the cases, two of which had mild encephalitis. Enterovirus was the most common cause of meningitis (50%), followed by HSV1 (15%), cytomegalovirus and dengue (10%, each).

CONCLUSIONS

We identified the viral agents causing encephalitis and meningitis in a higher proportion of cases than has been reported in other studies. Dengue was the most frequent cause of encephalitis, which surpassed HSV. In endemic areas, dengue should be investigated as an important cause of encephalitis. Normal CSF cellularity should not exclude dengue encephalitis. Enterovirus is known to be the leading cause of meningitis in children, but here we found it was also the main cause of the disease in adults. HSV1 should be investigated in patients with mild forms of encephalitis and meningitis.

Aseptic meningitis and encephalitis because of herpesviruses and enteroviruses in an immunocompetent adult population

BACKGROUND AND AIM

Human herpesviruses (HHVs) and enteroviruses (EVs) are the major causative agents of CNS viral infections. The aim of the study was to identify the etiology and determine the frequency of aseptic meningitis and encephalitis due to HHVs and EVs in an immunocompetent adult population.

METHODS

Eighty-one patients (ages >or=15) with aseptic meningitis or encephalitis treated in the Infectious Diseases Hospital of Thessaloniki, Greece, during 2003-2006, were included in the study. Polymerase chain reaction for detection of herpes- and enterovirus genome direct in cerebrospinal fluid samples was performed.

RESULTS

Based on clinical and laboratory data, 36/81 patients had meningitis and 45/81 had encephalitis. Etiology was defined in 11 patients (31%) with aseptic meningitis. EVs were the major causative agents (8/36, 22%), followed by varicella zoster virus (2/36, 5%) and herpes simplex virus-2 (HSV-2) (1/36, 3%). Etiology was identified in 8 of 45 (18%) patients with encephalitis, EV (4/45, 9%) and HSV-1 (4/45, 9%) being the most common pathogens.

CONCLUSION

Enteroviruses are the most common cause of adult aseptic meningitis and together with HSV-1 the main causes of encephalitis.

Diagnostic Techniques: Serological and Molecular Approaches

Virus laboratory diagnostics has an increasingly important role in modern patient care. Virological methods are needed to investigate the etiology of acute viral infection or the reactivation of a latent infection, as well as to follow virus load in antiviral treatments. Serological assays are also used for screening of blood products for the risk of certain chronic infections, evaluation of the immune status, and need for prophylatic treatments in connection with organ transplantations.

For diagnostic purposes the following approaches can be used: demonstration of presence of infectious virus or its structural components directly from a patient's specimens or investigation of specific antibody response in serum specimes. Virus isolation is used to demonstrate infectious virus in a patient's specimens, whereas nucleic acid amplification techniques, like polymerase chain reaction (PCR), are widely used to detect virus nucleic acids. Virus antigens are investigated by antigen detection assays. Serological diagnosis is based on either the demonstration of the presence of virus-specific IgM antibodies or a significant increase in the levels of specific IgG antibodies. Immunoassays are the most commonly used serological assays. Point-of-care tests (POC tests), both for antigens and antibodies, are also becoming more and more common in diagnostic use.

In order to reach the best diagnostic efficiency for each patient it is important to select the most suitable method using the right sample collected at the right time.

Diagnosis of Enteroviral Meningitis by Use of Polymerase Chain Reaction of Cerebrospinal Fluid, Stool, and Serum Specimens

BACKGROUND

Because enteroviruses can be detected in various clinical samples during enteroviral meningitis, we analyzed the combined diagnostic utility of polymerase chain reaction (PCR) of cerebrospinal fluid (CSF), feces, and serum for detection of enterovirus in specimens obtained from adults with aseptic meningitis or encephalitis.

METHODS

PCR results were analyzed for 34 adults for whom enteroviral meningitis was diagnosed on the basis of virus isolation and antibody detection in our hospital during 1999-2003. PCR results were also analyzed for 77 adults with meningitis or encephalitis of another defined cause for whom this assay was used for diagnostic evaluation during that period.

RESULTS

Twenty-six (76%) of 34 CSF samples and 24 (96%) of 25 fecal samples collected from patients with enteroviral meningitis had positive PCR results. The diagnostic yield of the test was lower for CSF specimens obtained >2 days after clinical onset, compared with CSF collected < or =2 days after onset. Instead, PCR of feces was highly useful also later, because 12 of the 13 fecal specimens obtained 5-16 days after clinical onset had positive test results. None of 75 CSF samples and 2 of 48 fecal samples obtained from patients with nonenteroviral infection had positive PCR results. All serum samples were PCR negative.

CONCLUSIONS

PCR of fecal specimens obtained throughout the course of enteroviral meningitis had the highest clinical sensitivity for detecting enterovirus. It is recommended that, in addition to performance of CSF PCR, fecal samples collected from patients with suspected enteroviral meningitis should be tested by PCR, especially when the duration of symptoms is >2 days.

Interstitial pneumonitis and coinfection of human herpesvirus 6 and Pneumocystis carinii in a patient with hypogammaglobulinemia

Human herpesvirus 6 (HHV-6) has occasionally been associated with cases of interstitial pneumonitis, mainly in individuals with impaired cellular immunity. Here we report for the first time severe interstitial pneumonitis with simultaneous HHV-6 and Pneumocystis carinii infections in the lung tissue of a young patient with hypogammaglobulinemia.

Viral meningitis

Viruses probably account for most cases of acute meningitis. Viral meningitis is often assumed to be a largely benign disease. For the commonest pathogens causing meningitis, enteroviruses, this is usually the case; however, for many of the other pathogens causing viral meningitis, and for common pathogens in the immunocompromised or infants, viral meningitis is frequently associated with substantial neurological complications and a significant mortality. Diagnostic methods for rapid and accurate identification of pathogens have improved over recent years, permitting more precise and earlier diagnoses. There have been fewer developments in therapies for viral meningitis, and there remain no effective therapies for most pathogens, emphasising the importance of prevention and early diagnosis. This review focuses on the presentation, diagnosis and management of viral meningitis and also covers the prevention of meningitis for pathogens where effective vaccines are available.

Méningites puriformes aseptiques chez l’adulte

OBJECTIVE

The objective of this study was to analyze the characteristics of a series of acute aseptic meningitis (AAM) (defined by sterile cerebrospinal fluid (CSF) with more than 10 leucocytes per mm3 and a neutrophilic polynuclear-rich formula). We analysed the initial management, the reasons for antibiotic and/or antiviral treatment, the aetiologies, the need for lumbar puncture and the progression...

METHOD

We retrospectively analyzed 32 cases of AAM (out of a total of 130 cases of meningitis) from two departments of internal medicine in Lyon, diagnosed between January 1996 and January 2003. Only the files fulfilling the AAM criteria were retained, selecting those with a minimum neutrophilic polynuclear level of 30% in the CSF.

RESULTS

The mean age was 32.6 years (range: 18-75) and predominantly male patients (59%). On admission, 87% of the patients exhibited fever, but only 9% remaining so for 72 hours. Viral syndrome before admission was noted in 59% of cases, with seasonal predilection (summer: 39%, winter: 35%). The motivation for lumbar puncture (LP) was meningeal syndrome (44%), headache (94%) and vomiting (47%). The average rate of neutrophils in the CSF on admission was 63% (range: 30-96). A control LP on Day 3 was performed 16 times (50%): mean PNN rate at 18% (range: 0-80), lymphocyte rate=68% (range: 20-95). Most of the patients (77.4%) had a C reactive protein (CRP) lower than 50 mg/l on admission (range: 5-320). A cerebral scan was performed 10 times (31%) and was abnormal 2 times (multiple cerebral abscesses, possible intracranial hypertension). An antibiotic (84%) and/or antiviral (34%) treatment was initiated. The evolution on Day 3 was favourable (87.5%): no fever, regression of the meningeal syndrome, with a mean duration of hospitalisation of 8.3 days (range: 1-60). Search for Herpes simplex virus and Enterovirus was made with PCR analysis in 20 cases (62.5%): no positivity for the herpes, but 9 for the Enterovirus. The systematic blood cultures were positive only once (staphylococcal infective endocarditis with cerebral abscesses). The diagnosis of bacterial meningitis was evoked 3 times (prior antibiotic treatment).

DISCUSSION

The frequency of Enterovirus AAM should encourage this type of investigation in order to withdraw the often initiated anti-infectious treatment rapidly, and hence avoid a second lumbar puncture.

Chlamydia pneumoniae together with collagenase-2 (MMP-8) in periodontal lesions

OBJECTIVE

Dental infections may be associated with subsequent atherosclerosis. In this regard we wanted to study if traces of Chlamydia pneumoniae can be found from deep periodontal pockets characterized with elevated collagenase-2 [matrix metalloproteinase (MMP)-8] levels in gingival crevicular fluid (GCF). Chlamydia pneumoniae has not previously been found to infect the oral cavity.

SUBJECTS AND METHODS

Subgingival samples of dental plaque were collected from 31 teeth in 12 adult periodontitis patients by means of sterile curettes and examined for C. pneumoniae using a quantitative PCR technique. GCF samples were also collected and assayed by an immunofluorometric assay (IFMA) for MMP-8.

RESULTS

Chlamydia pneumoniae RNA was demonstrated in a sample from one of the patients studied. Periodontal treatment eliminated the C. pneumoniae from the patient's subgingival dental plaque as well as reduced GCF MMP-8 level.

CONCLUSIONS

Our findings suggest that C. pneumoniae, which is not normally thought to be involved in periodontitis, can be found in dental plaque.

[Value of the polymerase chain reaction in the diagnosis of herpes infections of the nervous system]

OBJECTIVE

To assess the performance of a polymerase chain reaction (PCR) method in cerebrospinal fluid (CSF) for the diagnosis of nervous system infections caused by herpesvirus, and to estimate the incidence of encephalitis due to herpes simplex virus type 1 in the adult population of the island of Gran Canaria.

METHODS

We studied 330 CSF specimens from 312 patients (281 HIV-negative and 31 HIV-positive) remitted to investigate clinically suspected encephalitis or meningitis, or to study neuropathy or demyelinating disease. A multiplex PCR technique was used to detect herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus (VZV), human cytomegalovirus (CMV), Epstein-Barr virus and human herpesvirus type 6. The patients' clinical records were reviewed to establish the definite diagnosis.

RESULTS

Nine samples from eight patients (2.6%) showed positive results (9.7% of patients with pathological CSF and none with normal CSF). The eight patients had clinical and analytic findings of herpesvirus nervous system infection: HSV-1 DNA in four patients with encephalitis, HSV-2 DNA in one patient with meningitis, VZV DNA in two patients with meningitis and CMV DNA in one HIV-positive patient with encephalitis. Herpesvirus was the cause of 50% of encephalitis cases and 10% of meningitis cases. The incidence of HSV-1 encephalitis was five cases per million inhabitants per year.

CONCLUSIONS

Diagnosis of herpesvirus nervous system infections by PCR in CSF is not appropriate when CSF parameters are normal. We found a higher incidence of herpesvirus encephalitis than has been reported in other studies.