Varicella-zoster virus (VZV) glycoprotein E is a serological antigen for detection of intrathecal antibodies to VZV in central nervous system infections, without cross-reaction to herpes simplex virus 1. Clin Vaccine Immunol. 2011;18:1336-1342. [PMID: 21697341 DOI: 10.1128/cvi.05061-11]

Detection of Circulating VZV-Glycoprotein E-Specific Antibodies by Chemiluminescent Immunoassay (CLIA) for Varicella-Zoster Diagnosis

Varicella and herpes zoster are mild symptoms-associated diseases caused by varicella–zoster virus (VZV). They often cause severe complications (disseminated zoster), leading to death when diagnoses and treatment are delayed. However, most commercial VZV diagnostic tests have low sensitivity, and the most sensitive tests are unevenly available worldwide. Here, we developed and validated a highly sensitive VZV diagnostic kit based on the chemiluminescent immunoassay (CLIA) approach. VZV-glycoprotein E (gE) was used to develop a CLIA diagnostic approach for detecting VZV-specific IgA, IgG, and IgM. The kit was tested with 62 blood samples from 29 VZV-patients classified by standard ELISA into true-positive and equivocal groups and 453 blood samples from VZV-negative individuals. The diagnostic accuracy of the CLIA kit was evaluated by receiver-operating characteristic (ROC) analysis. The relationships of immunoglobulin-isotype levels between the two groups and with patient age ranges were analyzed. Overall, the developed CLIA-based diagnostic kit demonstrated the detection of VZV-specific immunoglobulin titers depending on sample dilution. From the ELISA-based true-positive patient samples, the diagnostic approach showed sensitivities of 95.2%, 95.2%, and 97.6% and specificities of 98.0%, 100%, and 98.9% for the detection of VZV-gE-specific IgA, IgG, and IgM, respectively. Combining IgM to IgG and IgA detection improved diagnostic accuracy. Comparative analyses on diagnosing patients with equivocal results displaying very low immunoglobulin titers revealed that the CLIA-based diagnostic approach is overall more sensitive than ELISA. In the presence of typical VZV symptoms, CLIA-based detection of high titer of IgM and low titer of IgA/IgG suggested the equivocal patients experienced primary VZV infection. Furthermore, while no difference in IgA/IgG level was found regarding patient age, IgM level was significantly higher in young adults. The CLIA approach-based detection kit for diagnosing VZV-gE-specific IgA, IgG, and IgM is simple, suitable for high-throughput routine analysis situations, and provides enhanced specificity compared to ELISA.

Encephalitis and Brain Abscess

PURPOSE OF REVIEW

This article reviews infections of the brain parenchyma and includes an overview of the epidemiology, pathogenesis, diagnostic approach, and management of infectious encephalitis and brain abscess.

RECENT FINDINGS

The epidemiology of infectious encephalitis and brain abscess has changed in recent years. Vaccination has reduced the incidence of certain viruses associated with encephalitis, while a decrease in fulminant otogenic infections has led to fewer brain abscesses associated with otitis media. However, changes in climate and human population density and distribution have enabled the emergence of newer pathogens and expanded the geographic range of others, and greater adoption of intensive immunosuppressive regimens for autoimmune conditions has increased the risk of opportunistic infections of the brain. The widespread use of early neuroimaging, along with improved diagnostic methodologies for pathogen detection, newer antimicrobial therapies with better brain penetration, and less invasive neurosurgical techniques, has resulted in better outcomes for patients with infectious encephalitis and brain abscess. Novel technologies including metagenomic next-generation sequencing are increasingly being applied to these conditions in an effort to improve diagnosis. Nevertheless, both infectious encephalitis and brain abscess continue to be associated with substantial mortality.

SUMMARY

Infectious encephalitis and brain abscess can present as neurologic emergencies and require rapid assessment, thorough and appropriate diagnostic testing, and early initiation of empiric therapies directed against infectious agents. Close clinical follow-up, proper interpretation of diagnostic results, and appropriate tailoring of therapeutic agents are essential to optimizing outcomes. Diagnosis and management of parenchymal brain infections are complex and often best achieved with a multidisciplinary care team involving neurologists, neurosurgeons, neuroradiologists, infectious disease physicians, and pathologists.

Recombinant Epstein-Barr virus glycoprotein 350 as a serological antigen

Epstein-Barr virus (EBV) glycoprotein 350 (gp350) is the most abundant glycoprotein expressed on the EBV envelope, the major target for neutralizing antibodies and also essential for virion attachment to B lymphocytes. Several studies have addressed EBV gp350 as a vaccine candidate, but less commonly as a potential antigen for serological assays. The aim of the current study was to develop a diagnostic tool to quantify EBV gp350-specific IgG in previously EBV-infected individuals. A construct encoding the extracellular domain of EBV gp350 (amino acid (aa) 1-860) was developed for expression in Chinese hamster ovary cells. Serum samples (n = 360) with known IgG serostatus against viral capsid antigen (VCA) and Epstein-Barr nuclear antigen 1 (EBNA1) were divided into three groups based on the differences in their serostatus: VCA + EBNA1+ (n = 120), VCA + EBNA1- (n = 120) and VCA-EBNA1- (n = 120). The samples were analyzed by indirect ELISA using recombinant EBV gp350 aa 1-860 as antigen. A clear majority, 108 of the 120 VCA + EBNA1+ samples, had detectable EBV gp350-specific IgG. Of the 120 VCA + EBNA1- samples, 79 had detectable EBV gp350-specific IgG. Only 2 of the 120 VCA-EBNA1- samples had detectable EBV gp350-specific IgG. The results reported here show that use of the EBV gp350 aa 1-860 ELISA can serve as a sensitive method for EBV-specific IgG detection in serum samples.

Alpha herpes virus type and viral load in intraocular fluids in patients with acute retinal necrosis

Objectives

To identify all patients tested positive for herpes viruses in intraocular samples between 2007 and 2016 in South-Western Sweden and evaluate which of these met the criteria of acute retinal necrosis (ARN). To compare viral load in intraocular samples and virus type with clinical outcome.

Method and analysis

Retrospective case series. Intraocular samples and serum were analysed with quantitative real-time PCR (qPCR) and presence of antibodies (IgG and IgM) were detected by ELISA in serum.

Results

Between 2007 and 2016, 13 patients met the clinical criteria of ARN and were PCR-positive in aqueous or vitreous for herpes simplex virus 1 (HSV1; n=4), herpes simplex virus 2 (HSV2; n=3) and varicella zoster virus (VZV; n=6). None of the patients tested positive for cytomegalovirus (n=13) or Epstein Barr virus (n=2) met the criteria of ARN. All ARN patients had specific serum IgG and three patients exhibited virus DNA in serum. There was no correlation between high viral load and worse visual outcome. However, higher viral loads were seen in samples taken earlier in the disease process. Median age was higher (p=0.049) in VZV-ARN than for HSV-ARN patients (60.5 and 45.4 years, respectively) with a tendency of worse best corrected visual acuity at presentation (1.62 and 0.79 log MAR, respectively; p=0.079).

Conclusion

ARN is a reactivation of alpha herpes virus and presence of herpes DNA in serum may occur. VZV-ARN are older than HSV-ARN patients. High viral load does not appear to be a predictor of worse visual outcome, but rather indicates earlier sampling.

Localization of VZV in saliva of zoster patients

Varicella zoster virus (VZV) in saliva from six herpes zoster patients and one chickenpox patient was found to be exclusively associated with epithelial cells by confocal microscopy. VZV localization with antibody specific to the VZV glycoprotein E was detected primarily on the membrane but was also inside the cell. Epithelial cells with VZV were still present in saliva in one out of two tested zoster patients after 10 months of recovery. Saliva from healthy controls (non-shingles patients, n = 5) did not show any sign of VZV by polymerase chain reaction or by confocal microscopy. No VZV was found in the liquid fraction of saliva. Further work is required to understand the movement of VZV in the saliva cells of infected patients.

Infectious encephalitis: Management without etiological diagnosis 48hours after onset

Introduction

The etiological diagnosis of infectious encephalitis is often not established 48 hours after onset. We aimed to review existing literature data before providing management guidelines.

Method

We performed a literature search on PubMed using filters such as “since 01/01/2000”, “human”, “adults”, “English or French”, and “clinical trial/review/guidelines”. We also used the Mesh search terms “encephalitis/therapy” and “encephalitis/diagnosis”.

Results

With Mesh search terms “encephalitis/therapy” and “encephalitis/diagnosis”, we retrieved 223 and 258 articles, respectively. With search terms “encephalitis and corticosteroid”, we identified 38 articles, and with “encephalitis and doxycycline” without the above-mentioned filters we identified 85 articles. A total of 210 articles were included in the analysis.

Discussion

Etiological investigations must focus on recent travels, animal exposures, age, immunodeficiency, neurological damage characteristics, and potential extra-neurological signs. The interest of a diagnosis of encephalitis for which there is no specific treatment is also to discontinue any empirical treatments initially prescribed. Physicians must consider and search for autoimmune encephalitis.

Microbiology laboratory and the management of mother-child varicella-zoster virus infection

Varicella-zoster virus, which is responsible for varicella (chickenpox) and herpes zoster (shingles), is ubiquitous and causes an acute infection among children, especially those aged less than six years. As 90% of adults have had varicella in childhood, it is unusual to encounter an infected pregnant woman but, if the disease does appear, it can lead to complications for both the mother and fetus or newborn. The major maternal complications include pneumonia, which can lead to death if not treated. If the virus passes to the fetus, congenital varicella syndrome, neonatal varicella (particularly serious if maternal rash appears in the days immediately before or after childbirth) or herpes zoster in the early years of life may occur depending on the time of infection. A Microbiology laboratory can help in the diagnosis and management of mother-child infection at four main times: (1) when a pregnant woman has been exposed to varicella or herpes zoster, a prompt search for specific antibodies can determine whether she is susceptible to, or protected against infection; (2) when a pregnant woman develops clinical symptoms consistent with varicella, the diagnosis is usually clinical, but a laboratory can be crucial if the symptoms are doubtful or otherwise unclear (atypical patterns in immunocompromised subjects, patients with post-vaccination varicella, or subjects who have received immunoglobulins), or if there is a need for a differential diagnosis between varicella and other types of dermatoses with vesicle formation; (3) when a prenatal diagnosis of uterine infection is required in order to detect cases of congenital varicella syndrome after the onset of varicella in the mother; and (4) when the baby is born and it is necessary to confirm a diagnosis of varicella (and its complications), make a differential diagnosis between varicella and other diseases with similar symptoms, or confirm a causal relationship between maternal varicella and malformations in a newborn.

Immunogenicity of varicella zoster virus glycoprotein E DNA vaccine

In the present study a eukaryotic expression vector of varicella zoster virus (VZV) glycoprotein E (gE) was constructed and enabled to express in COS7 cells. Furthermore, a specific immune response against the VZV gE eukaryotic expression plasmid was induced in BALB/c mice. The VZV gE gene was amplified using polymerase chain reaction (PCR) and cloned into a eukaryotic expression vector, pcDNA3.1. The recombinant vector was subsequently transfected into COS7 cells using a liposome transfection reagent. The recombinant protein was instantaneously expressed by the transfected cells, as detected by immunohistochemistry, and the recombinant pcDNA-VZV gE plasmid was subsequently used to immunize mice. Tissue expression levels were analyzed by reverse transcription-PCR. In addition, the levels of serum antibodies and spleen lymphocyte proliferation activity were investigated. The amplified target gene included the full-length gE gene (~2.7 kb), and the recombinant expression vector induced gE expression in COS7 cells. In addition, the expression plasmid induced sustained expression in vivo following immunization of mice. Furthermore, the plasmid was capable of inducing specific antibody production and effectively stimulating T cell proliferation. Effective humoral and cellular immunity was triggered in the mice immunized with the VZV gE eukaryotic expression vector. The results of the present study laid the foundation for future research into a VZV DNA vaccine.

CNS infections in patients with hematological disorders (including allogeneic stem-cell transplantation)-Guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO)

Diagnosis of CNS infections remains a great challenge in patients with hematological disorders since symptoms might both be masked and be mimicked by other conditions such as metabolic disturbances or consequences from antineoplastic treatment. Thus, awareness of this complication is crucial and any suspicion of a CNS infection should lead to timely and adequate diagnostics and treatment to improve the outcome in this population.

Infections of the central nervous system (CNS) are infrequently diagnosed in immunocompetent patients, but they do occur in a significant proportion of patients with hematological disorders. In particular, patients undergoing allogeneic hematopoietic stem-cell transplantation carry a high risk for CNS infections of up to 15%. Fungi and Toxoplasma gondii are the predominant causative agents. The diagnosis of CNS infections is based on neuroimaging, cerebrospinal fluid examination and biopsy of suspicious lesions in selected patients. However, identification of CNS infections in immunocompromised patients could represent a major challenge since metabolic disturbances, side-effects of antineoplastic or immunosuppressive drugs and CNS involvement of the underlying hematological disorder may mimic symptoms of a CNS infection. The prognosis of CNS infections is generally poor in these patients, albeit the introduction of novel substances (e.g. voriconazole) has improved the outcome in distinct patient subgroups. This guideline has been developed by the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO) with the contribution of a panel of 14 experts certified in internal medicine, hematology/oncology, infectious diseases, intensive care, neurology and neuroradiology. Grades of recommendation and levels of evidence were categorized by using novel criteria, as recently published by the European Society of Clinical Microbiology and Infectious Diseases.

Performance of a multiplexed serological microarray for the detection of antibodies against central nervous system pathogens

Central nervous system (CNS) infections have multiple potential causative agents for which simultaneous pathogen screening can provide a useful tool. This study evaluated a multiplexed microarray for the simultaneous detection of antibodies against CNS pathogens. The performance of selected microarray antigens for the detection of IgG antibodies against herpes simplex virus 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus (VZV), adenovirus, Mycoplasma pneumoniae and Borrelia burgdorferi sensu lato, was evaluated using serum sample panels tested with reference assays used in a routine diagnostic laboratory. The microarray sensitivity for HSV-1, HSV-2, VZV, adenovirus and M. pneumonia ranged from 77% to 100%, and the specificity ranged from 74% to 97%. Very variable sensitivities and specificities were found for borrelial antigens of three different VlsE protein IR(6) peptide variants (IR6p1, IR6p2, IR6p4) and three recombinant decorin binding proteins A (DbpA; DbpAIa, DbpA91, DbpAG40). For single antigens, good specificity was shown for antigens of IR6p4 and DbpAIa (96%), while DbpA91, IR6p1 and IR6p2 were moderately specific (88–92%). The analytical sensitivity of the microarray was dependent on the borrelial IgG concentration of the specimen. The overall performance and technical features of the platform showed that the platform supports both recombinant proteins, whole viruses and peptides as antigens. This study showed diagnostic potential for all six CNS pathogens, including Borrelia burgdorferi sensu lato, using glutaraldehyde based microarray, and further highlighted the importance of careful antigen selection and the requirement for the use of multiple borrelial antigens in order to increase specificity without a major lack of sensitivity.

•

To find a suitable microarray platform that supports different kinds of antigens

•

To evaluate the feasibility of a multiplexed glutaraldehyde based microarray

•

To detect simultaneously different viral and bacterial antibodies

•

Performance of the platform proved promising

Changes to anti-JCV antibody levels in a Swedish national MS cohort

BACKGROUND

The anti-JC virus (JCV) antibody status has been introduced to stratify patients with multiple sclerosis (MS) for higher or lower risk of progressive multifocal leukoencephalopathy (PML).

OBJECTIVE

To assess the potential utility of anti-JCV antibody levels for earlier diagnosis or prediction of PML.

METHODS

An analytically validated antibody assay was used to determine serological status, normalised optical density values, and dilution titres for anti-JCV antibodies. The method was applied to stored sera of 1157 patients with MS including five cases of PML, all enrolled in the Swedish pharmacovigilance study for natalizumab (NAT). Anticytomegalovirus (CMV) and antivaricella-zoster (VZV) antibody levels served as controls.

RESULTS

Prior to treatment with NAT, anti-JCV antibody levels were stable in the anti-JCV positive patients. During therapy, a slight decrease in anti-JCV and anti-VZV antibody levels, but not anti-CMV antibody levels, was observed. All five patients who developed PML showed a mild to moderate increase in anti-JCV antibody levels at time of PML diagnosis; pre-PML samples suggested that this increase might start already prior to diagnosis of PML.

CONCLUSIONS

Treatment initiation with NAT may lead to a slight decrease in anti-JCV and anti-VZV antibody levels, suggestive of a mild suppressive effect of NAT on antibody levels. Our findings in five cases of PML demonstrate that the onset of PML can be accompanied by increasing anti-JCV antibodies in serum. Monitoring of anti-JCV antibody levels could potentially be used as a tool for prediction or earlier diagnosis of PML during NAT treatment for MS. Further studies are warranted.

Safety and immunogenicity of an AS01-adjuvanted varicella zoster virus subunit candidate vaccine (HZ/su): a phase-I, open-label study in Japanese adults

An adjuvanted recombinant subunit candidate vaccine (HZ/su) containing varicella zoster virus envelope glycoprotein E was developed for the prevention of herpes zoster and its complications. This study evaluated safety and reactogenicity of HZ/su in an ethnic Japanese population. This was a phase I, open-label and single-center study conducted between March and November of 2010 in Australia. Twenty healthy ethnic Japanese subjects, aged 18–30 y and 50–69 y (1:1) were enrolled. Subjects were administered two doses of HZ/su vaccine according to a 0, 2-mo schedule. Local and general solicited symptoms were recorded for 7 d post-vaccination. Unsolicited symptoms were recorded for 30 d post-vaccination. Serious adverse events (SAEs), new onset of autoimmune disease (NOAD), other potential immune mediated disorders and HZ cases were recorded throughout the study period. All 20 subjects were included in the according-to-protocol cohort for safety. A total of 18 subjects were included in the according-to-protocol cohort for immunogenicity: 10 in the 18–30 y age group and 8 in the 50–69 y age group. The most commonly reported local and general solicited symptoms were pain and fatigue in both groups. Back pain (in the 18–30 y age group) and chills (in the 50–69 y age group) were the most frequently reported unsolicited symptoms. There were no reports of death, SAEs, NOADs, other autoimmune mediated inflammatory disorder or suspected HZ cases. This study indicated that the two-dose regimen of HZ/su exhibited a clinically acceptable safety profile in healthy young and older ethnic Japanese adults.