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Despite scarcity of data, in recent years, human parvovirus B19 (PVB19) has been emerging as an important pathogen in acute encephalitis syndrome (AES). But, PVB19 virus is mostly looked for only after the exclusion of other common pathogens implicated in AES. Hence, this study was conducted to correlate clinical, radiological, and sequencing data to establish the crucial role of PVB19 in AES. Cerebrospinal fluid and/or serum samples were collected from AES patients as per WHO criteria and tested by ELISA, real-time PCR and bacterial culture sensitivity for various pathogens. PVB19 positive samples were subjected to sequencing. PVB19 attributed to 5% of total AES cases in the present study with fatalities in two of eight cases. Two isolates of PVB19 belonged to Genotype 1 A whereas one belonged to Genotype 3B. On multivariate analysis of predictive symptoms of PVB19 AES cases, blurring of vision (odds ratio [OR] 20.67; p = 0.001) was found to be significant independent predictor of PVB19 AES. Six of eight patients (two encephalitis specific and four nonspecific) had abnormal radiological findings. Hence, being an emerging viral pathogen, PVB19 should be included in the diagnostic algorithm of AES for prompt diagnosis and definitive management to prevent undesired neurological sequelae., (© 2024 Wiley Periodicals LLC.)

Enterovirus 71 (EV71) is the main pathogen of hand-foot-mouth disease (HFMD) and causes several neurological complications. As new strains of EV71 are constantly discovered, it is important to understand the genomic characteristics of the viruses and the mechanism of virulence. Herein, we isolated five strains of EV71 from HFMD patients with or without neurovirulence and sequenced their whole genomes. We then performed whole genome sequence analysis of totally 36 EV71 strains. The phylogenetic analysis of the VP1 region revealed all five isolated strains are clustered into C4a of C4 subgenotype. In addition, by comparing the complete genome sequences of 36 strains, 253 variable amino acid positions were found, 14 of which were identified to be associated with neurovirulence (P < 0.05). Moreover, a similar pattern of amino acid variants combination was identified in four strains without neurovirulence, indicating this type of variant pattern might be associated with avirulence. The strains with neurovirulence appeared to be distinguished from those without neurovirulence by the variants in VP1 and P2 regions, implying VP1 and P2 are the important regions associated with neurovirulence. Indeed, 3-D modeling of VP1 and P2 regions of non-neurovirulent and neurovirulent strains revealed that the different variants resulted in different protein structures and amino acid composition of ligand binding site, which might account for their difference in neurovirulence. In summary, our study reveals 14 variable amino acid positions of VP1, P2 and P3 regions are related to the virulence and that mutations in the capsid proteins of EV71 might contribute to neurovirulence., (© 2018 Wiley Periodicals, Inc.)

The aim of this study was to report a minor outbreak of enterovirus A71 (EV-A71) infection in Poland and characterize isolates from cases of severe neurological infection detected in 2013 and 2016. Phylogenetic analysis revealed that Polish strains belonged to the C genogroup: C1, C2, and C4. Severe neurological manifestations as encephalitis or acute flaccid paralysis (AFP), were associated with all detected subgenogroups. The C2 subgenogroup was associated with the outbreak in Gdansk, with serious cases of AFP, myelitis, cerebellitis, encephalitis, but also with mild, sporadic cases of aseptic meningitis, in other Polish cities. Data from the study established relationships of EV-A71 from Poland with previously characterized strains and confirmed the importance of high quality enterovirus surveillance with international reach., (© 2017 Wiley Periodicals, Inc.)

Toscana virus (TOSV) is identified in sandflies, animals, and humans around the Mediterranean Sea. TOSV has not been reported in Australia. During investigations of cerebrospinal fluid samples from patients with encephalitis, TOSV genetic sequences were identified in a traveler returning to Australia from Europe. TOSV should be considered, especially during May to October, in travelers to Australia who embarked in countries in and around the Mediterranean Sea and who subsequently present for medical care because of neurological symptoms., (© 2017 Wiley Periodicals, Inc.)

Objective: Immunodeficient patients are particularly vulnerable to neuroinvasive infections that can be challenging to diagnose. Metagenomic next generation sequencing can identify unusual or novel microbes and is therefore well suited for investigating the etiology of chronic meningoencephalitis in immunodeficient patients., Methods: We present the case of a 34-year-old man with X-linked agammaglobulinemia from Australia suffering from 3 years of meningoencephalitis that defied an etiologic diagnosis despite extensive conventional testing, including a brain biopsy. Metagenomic next generation sequencing of his cerebrospinal fluid and brain biopsy tissue was performed to identify a causative pathogen., Results: Sequences aligning to multiple Cache Valley virus genes were identified via metagenomic next generation sequencing. Reverse transcription polymerase chain reaction and immunohistochemistry subsequently confirmed the presence of Cache Valley virus in the brain biopsy tissue., Interpretation: Cache Valley virus, a mosquito-borne orthobunyavirus, has only been identified in 3 immunocompetent North American patients with acute neuroinvasive disease. The reported severity ranges from a self-limiting meningitis to a rapidly fatal meningoencephalitis with multiorgan failure. The virus has never been known to cause a chronic systemic or neurologic infection in humans. Cache Valley virus has also never previously been detected on the Australian continent. Our research subject traveled to North and South Carolina and Michigan in the weeks prior to the onset of his illness. This report demonstrates that metagenomic next generation sequencing allows for unbiased pathogen identification, the early detection of emerging viruses as they spread to new locales, and the discovery of novel disease phenotypes. Ann Neurol 2017;82:105-114., (© 2017 The Authors Annals of Neurology published by Wiley Periodicals, Inc. on behalf of American Neurological Association.)

Human parechovirus (HPeV) and human herpes virus-6 (HHV-6) are acquired commonly in infancy and associated with central nervous system infection. The prevalence of HPeV and HHV-6 in the cerebrospinal fluid (CSF) of infants tested for enterovirus (EV) and herpes-simplex virus (HSV) is unknown. All stored CSF samples from EV or HSV testing in infants less than 6 months of age at Children's Hospital Colorado between January 1, 2010 and December 31, 2011 were tested for HPeV, HHV-6, EV, and HSV by PCR. Clinical characteristics and epidemiological data were collected using retrospective electronic chart review. Of 239 infants tested, 29 cases of EV (12.1%), 7 cases of HPeV (2.9%), 5 cases of HHV-6 (2.1%), and 5 cases of HSV (2.1%) were identified with no bacterial co-infections. HPeV cases occurred between July and October in infants with median age of 24 days. Infants with HPeV had a median maximum temperature of 39 °C, median fever duration of 3 days and median peripheral white blood cell count of 5.2 × 10(3)/μL. HHV-6 cases occurred in infants with median age of 61 days without seasonality. Five percent of infants less than 6 months of age undergoing testing for EV or HSV have HPeV or HHV-6 in the CSF. Targeting testing of HPeV towards febrile infants less than 2 months of age with leukopenia in the late summer to early fall, and HHV-6 towards older infants may increase diagnostic yield. The clinical and fiscal impact of testing infants for HPeV and HHV-6 needs to be determined., (© 2015 Wiley Periodicals, Inc.)

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., (© 2014 Wiley Periodicals, Inc.)

In the past 3 years, the 2009 pandemic influenza virus H1N1 (pH1N1) has led to many severe or fatal cases. The virus-related factors that cause severe or fatal disease are not clear. The clinical and molecular characteristics of pH1N1 infections with severe or fatal disease were examined to understand the correlation between pH1N1 infection and disease severity. Since 2009, three pH1N1 influenza epidemic outbreaks have occurred in Shenzhen, China. One hundred forty-six severe cases were confirmed in the first wave in 2009. In severe cases, a high proportion (49.3%) of patents displayed high fever (>39.0°C), and 73.2% of patients had pneumonia and tracheobronchitis. Seven fatal cases were recorded: three with viral encephalitis and four with respiratory failure. The results of sequencing and phylogenetic analysis showed that the viruses from fatal or severe cases were scattered throughout the phylogenetic tree. Four substitutions (D222G, D222N, D222E, and Q223R) were observed on the 220-loop of the receptor-binding sites of the HA gene. Both D222G and D222N were associated statistically with severe disease. The 2011 viruses had evolved into two distinct branches. Ten specific point mutations occurred in the 2011 virus. In summary, high fever, lower respiratory tract infections and serious complications were the main features of severe cases. Gene variation seemed not to be the main reason for severe disease. Vaccination is the effective mean to prevent infection and severe disease., (Copyright © 2012 Wiley Periodicals, Inc.)

The novel pandemic (pdm) influenza A (H1N1) 2009 virus caused an epidemic of critical illness, with some patients developing severe acute respiratory distress syndrome. Pdm H1N1 2009 infection has been reported to cause fatal encephalopathy and myocarditis as well as pneumonia. To investigate the actual characteristics of the encephalopathy associated with pdm H1N1 2009 infection in Japan, questionnaires were distributed and information collected on 207 cases of encephalopathy during one season. The results of the survey showed that encephalopathy was reported predominantly in males. The outcome was recorded in 188 of the 207 cases; 16 of 188 patients (8.5%) died, while 23 (12.2%) had sequelae. Serious cases were distributed across all age groups. Febrile convulsion was noted at a higher rate in medical past-history in cases without sequelae (40 of the 149 cases; 27%) than in serious cases. In contrast, pre-existing epilepsy and mental retardation were observed more frequently in serious cases. Twelve cases exhibited biphasic seizures; one-half of these had sequelae, but none was fatal. Ten cases were accompanied by high cytokine levels, and three of these children died. Among the 149 cases with good outcomes, 29 of 116 cases (25%) showed abnormalities on MRI, and 14 of these demonstrated reversible splenial lesions. Abnormal behaviors, especially delirium and visual hallucinations, were observed more frequently in cases without sequelae. In conclusion, pdm H1N1 2009 infection-associated encephalopathy was a critical disease in children, with rapidly progressive characteristics similar to those of seasonal influenza-associated encephalopathy., (Copyright © 2012 Wiley Periodicals, Inc.)

The etiology of encephalitis and meningitis, serious diseases of the central nervous system (CNS), in most cases remains unknown. The importance of establishing a diagnosis however, becomes even more important as advances are made in effective therapy. Molecular methods of detection, in particular, PCR, are being used routinely and have established a place in the arsenal of tools for diagnosis of CNS infections. In this study a viral etiological agent was detected by PCR in 340 of the total 2,357 specimens from patients who exhibited symptoms of encephalitis or meningitis. The detection rate increased from 8.9% during the first year of the study to 14.8% during the second year of the study with improved methodology and an expanded panel of viral agents. Methods were enhanced by developing real-time PCR assays (some multiplexed), using increased automation, superior nucleic acid extraction, and reverse transcription (RT) methods, and incorporation of an internal extraction control. Additionally, adenovirus and human herpes virus 6 (HHV-6) were added to the original panel of 10 viruses that included enteroviruses, herpesviruses, and arboviruses. The most common viruses detected were enteroviruses (129; 5.5%), Epstein-Barr virus (EBV) (85; 3.6%), herpes simplex viruses (HSVs) 1 and 2 (67; 2.8%), and varicella zoster virus (VZV) (44; 1.9%)., (Copyright © 2011 Wiley Periodicals, Inc.)

Expression of matrix metalloproteinases (MMPs), especially MMP9 correlates with blood-brain barrier (BBB) disruption during many neuroinflammatory diseases. During neurotropic coronavirus virus (JHMV) induced encephalomyelitis, MMP9 activity is restricted to neutrophils. Furthermore, myeloid cell depletion implicated MMP9 in facilitating leukocyte central nervous system (CNS) infiltration via loss of BBB integrity. The requirement of MMP9 in BBB disruption was thus assessed in JHMV infected MMP9 deficient (MMP9(-/-)) mice. Depletion of neutrophils reduced CNS accumulation of monocytes and T cells, albeit without affecting overall pathogenesis. By contrast, infected MMP9(-/-) mice revealed no differences in CNS leukocyte infiltration, composition or localization, consistent with BBB disruption similar to wild-type (WT) mice. Unimpaired T cell mediated virus control supported an unexpectedly redundant role of MMP9 in promoting leukocyte access to the brain parenchyma. Although MMP9 deficiency did not expand the overall limited pattern of MMP expression during JHMV infection, it coincided with MMP3 upregulation. MMP3 expression remained largely confined to astrocytes, similar to WT mice. These data demonstrate that neutrophil-derived MMP9 is not the sole mediator facilitating parenchymal leukocyte entry via BBB disruption during viral encephalomyelitis. Moreover, significantly enhanced MMP3 expression by astrocytes in infected MMP9(-/-) mice suggests an active role of resident cells in participating and potentially collaborating with infiltrating cells in regulating BBB permeability. Overall, these results highlight the complexity of targeting individual MMPs as a strategy to regulate inflammation., (Copyright © 2011 Wiley-Liss, Inc.)

Rapid detection of viral pathogens is crucial for antiviral therapy. High-density 60-70-mer oligonucleotide microarrays have been explored for broad detection of many viruses. However, relatively low specificity and the complex analytical processes are the major limitations when pan-viral oligonucleotide microarrays are used to detect viral pathogens. In this study, genus-specific oligonucleotides were used as probes and modified sample preparations were carried out to improve the specificity and accuracy of the pan-viral oligonucleotide microarray. Genus-specific 63-mer oligonucleotide probes were used for screening human pathogenic RNA viruses. A total of 628 oligonucleotide probes covering 32 RNA viral genera from 14 viral families were used. The number of oligonucleotide probes was decreased to simplify the analytical process of hybridization and to minimize cross-hybridization. Host genomes were removed by DNase I/RNase T1 digestion before viral nucleic acid extraction, and non-ribosomal hexanucleotides were used for reverse transcription to minimize interference of host genomes. Cultured viruses were used for microarray validation. The microarray was validated by cultured isolates that belonged to five viral genera. By using DNase I/RNase T1 digestion before viral nucleic acid extraction and non-ribosomal hexanucleotides for reverse transcription, the specificity of the microarray was improved. Furthermore, the analytical process of hybridization results was simplified. The specificity of pan-viral microarray could be improved by using genus-specific oligonucleotides as probes and by using non-ribosomal hexanucleotides for reverse transcription. Combined with subsequent degenerate reverse transcriptase-polymerase chain reaction and sequencing processes, this improved genus-specific oligonucleotides microarray provides a relatively flexible strategy for diagnosis of RNA virus diseases., (Copyright © 2011 Wiley-Liss, Inc.)

Primary human herpesvirus-6 (HHV-6) infection is a common cause of acute sporadic encephalopathy in Japanese children. Occasionally, HHV-6 is not detected in the cerebrospinal fluid (CSF) of patients with encephalopathy, for example, in those with focal viral encephalitis, such as herpes simplex viral encephalitis. This indicates that HHV-6 encephalopathy is caused by an indirect mechanism, although this is not fully understood. HHV-6 DNA, cytokines (interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12 p70, tumor necrosis factor-alpha, interferon-gamma), and matrix metalloproteinase-9 were quantitated in both the CSF and serum of 13 patients with HHV-6 encephalopathy during the acute phase of the disease. HHV-6 DNA was detected in the CSF of seven patients with HHV-6 encephalopathy. The viral DNA concentration was significantly higher in serum than in CSF (mean 1.64 x 10(4) vs. 5.70 x 10(1) copies/ml; P = 0.003). The lack or low level of viral DNA in the CSF samples suggests that direct invasion of the central nervous system by HHV-6 is not the main cause of encephalopathy. Additionally, the IL-10 concentration was significantly higher in serum than in CSF (P < 0.001), whereas there was no significant difference in IL-6 levels between the CSF and serum samples. Interestingly, the IL-8 concentration was significantly higher in CSF than in serum (P = 0.038). The distribution of these cytokines differed between CSF and serum. The high CSF concentration of IL-8 could play an important role in the pathogenesis of encephalopathy., ((c) 2010 Wiley-Liss, Inc.)

Astrocyte infection with human immunodeficiency virus (HIV) is considered rare, so astrocytes are thought to play a secondary role in HIV neuropathogenesis. By combining double immunohistochemistry, laser capture microdissection, and highly sensitive multiplexed polymerase chain reaction to detect HIV DNA in single astrocytes in vivo, we showed that astrocyte infection is extensive in subjects with HIV-associated dementia, occurring in up to 19% of GFAP+ cells. In addition, astrocyte infection frequency correlated with the severity of neuropathological changes and proximity to perivascular macrophages. Our data indicate that astrocytes can be extensively infected with HIV, and suggest an important role for HIV-infected astrocytes in HIV neuropathogenesis.

A rare case of EBV encephalitis initially diagnosed as Herpes simplex infection is presented to highlight the importance of EBV specific intrathecal ELISA and liquor PCR based differential diagnosis when Herpes simplex encephalitis specific clinical symptoms, neuroimaging signs and electroencephalographic features are present. The case report also suggests that acyclovir treatment might be beneficial for the long term outcome in adult EBV encephalitis patients., (2008 Wiley-Liss, Inc.)

Objective: To assess the role of human parechoviruses (HPeVs) as a cause of neonatal cerebral infection and to report neuroimaging findings of newborn infants with encephalitis caused by HPeVs., Methods: Clinical presentation, cranial ultrasonography, magnetic resonance imaging (MRI) findings, and neurodevelopmental outcome of 10 infants admitted to a neonatal intensive care unit and diagnosed with encephalitis caused by HPeVs are reported., Results: Nine of 10 infants, with a gestational age of 29 to 41 weeks, presented at 36 to 41 weeks postmenstrual age with clinical seizures. Seven had a fever and six had a rash. Clinical presentation was similar to that of infants with enterovirus infection. Cranial ultrasonography showed increased echogenicity in the periventricular white matter in all infants. Neonatal MRI confirmed white matter changes in nine infants, which changed to gliosis on later MRI. Outcome was variable with cerebral palsy in one, a suspect outcome at 18 months in one, learning disabilities at 7 years of age in one, epilepsy in one, and normal neurodevelopmental outcome in five children. Follow-up of one infant was only 9 months., Interpretation: HPeVs should be added to the list of neurotropic viruses that may cause severe central nervous system infection in the neonatal period. White matter injury can be visualized with cranial ultrasonography, but more detailed information is obtained with MRI and especially diffusion-weighted imaging. Because clinical presentation of HPeV encephalitis is similar to that of enterovirus, real-time polymerase chain reaction for both viruses should be performed in atypical presentation of neonatal seizures.

A hospital-based surveillance was undertaken between May 2005 and April 2006 to elucidate the contribution of Chandipura virus (CHPV) to acute viral encephalitis cases in children, seroconversion in recovered cases and to compare the seroprevalences of anti-CHPV IgM and N antibodies in areas reporting cases with those without any case of acute viral encephalitis. During this period, 90 cases of acute encephalitis were hospitalized in the pediatric wards of Mahatma Gandhi Memorial (MGM) Hospital, Warangal. There were 49 deaths (Case Fatality Rate, i.e., CFR of 54.4%). Clinical samples and records were obtained from 52 suspected cases. The cases were below 15 years, majority in 0-4 years (35/52, 67.3%). Computerized tomography (CT) scans and cerebro-spinal fluid (CSF) picture favored viral etiology. No neurological sequelae were observed. CHPV etiology was detected in 25 cases (48.1%, n = 52; RNA in 20, IgM in 3 and N antibody seroconversion in 2). JEV etiology was detected in 5 cases (IgM in 4 cases and seroconversion in 1 case). Anti-CHPV IgM seroprevalence in contacts (26/167, 15.6%) was significantly higher (P < 0.05) than in non-contacts (11/430, 2.6%); which was also observed in children <15 years (19/90, 21.1% vs. 3/109, 2.7%). Anti-CHPV N antibody seroprevalence in <15 years contacts (66/90, 73.3%) and non-contacts (77/109, 70.6%) was significantly lower (P < 0.05) than in contacts (75/77, 97.4%) and non-contacts (302/321, 94.1%) more than 15 years respectively. CHPV appears to be the major cause of acute viral encephalitis in children in endemic areas during early monsoon months., ((c) 2007 Wiley-Liss, Inc.)

Theiler's murine encephalomyelitis virus (TMEV) infection in the central nervous system (CNS) induces a demyelinating disease similar to human multiple sclerosis. TMEV infection results in activation of various chemokine and cytokine genes that are important in the initiation of an inflammatory response. We have previously shown that the production of these chemokines and cytokines in astrocytes is induced via the NF-kappaB pathway following TMEV and Coxsackie virus infection. In this study, we investigated whether the NF-kappaB-dependent inflammatory responses after TMEV infection is triggered through TLR3 and/or TLR7. The activation of NF-kappaB or IRF/ISRE, as well as the production of both MCP-1/CCL2 and IL-8/CXCL8, was observed in only TLR3-transfected HEK 293 cells, but not in TLR7-tranfected cells. The potential involvement of TLR3 in mouse embryonic fibroblasts and primary astrocytes was further investigated following transfection with wildtype or dominant negative form of TLRs and MyD88, as well as astrocytes from TLR3- and MyD88-deficient mice. Similarly, the activation of transcription factors and chemokine genes is induced in these mouse cells through primarily TLR3 signaling pathway, but not TLR7 or other MyD88-mediated pathways following TMEV infection. However, the TLR3-mediated cellular activation does not appear to affect the level of viral replication in astrocytes. These results strongly suggest that TLR3-signaling by TMEV alone is sufficient to induce the initial inflammatory cytokine responses that could be very important for the outcome of virus-induced encephalitis and/or demyelinating diseases, such as multiple sclerosis.

A 55-year-old bat conservationist was admitted to Ninewells Hospital, Dundee, Scotland, on November 11, 2002, with an acute haematemesis. He gave a 5-day history of pain and paraesthesia in the left arm, followed by increasing weakness of his limbs with evidence of an evolving encephalitis with cerebellar involvement. The patient had never been vaccinated against rabies and did not receive postexposure treatment. Using a hemi-nested reverse transcriptase-polymerase chain reaction (RT-PCR), saliva samples taken intravitam from different dates proved positive for rabies. A 400-bp region of the nucleoprotein gene was sequenced for confirmation and identified a strain of European bat lyssavirus (EBLV) type 2a. The diagnosis was confirmed using the fluorescent antibody test (FAT) and by RT-PCR on three brain samples (cerebellum, medulla, and hippocampus) taken at autopsy. In addition, a mouse inoculation test (MIT) was performed. Between 13 and 17 days postinfection, clinical signs of a rabies-like illness had developed in all five inoculated mice. Brain smears from each infected animal were positive by the FAT and viable virus was isolated. This fatal incident is only the second confirmed case of an EBLV type-2 infection in a human after exposure to bats.

Antibody avidity tests have been used to detect primary human herpesvirus-7 (HHV-7) infection in an immunocompetent 19-year-old man with encephalitis and flaccid paralysis for which all other suspected causes had been excluded. The finding of the viral DNA in the cerebrospinal fluid (CSF) but not in serum samples suggests that primary HHV-7 infection with invasion of the central nervous system and consequential disease had occurred. As almost all adults are infected with HHV-7 in early childhood, the present case of delayed primary infection with serious symptoms must be exceptionally rare and no cases of such late acquisition of the virus have been documented in the literature. This report of HHV-7 DNA in the CSF of an immunocompetent adult is also unique., (Copyright 2002 Wiley-Liss, Inc.)

Previous studies have suggested a neuroinvasive and neuropersistent potential of human herpesvirus 7 (HHV-7). In this report, a case of fatal encephalitis is described and its association with HHV-7 infection is discussed. An 8-year-old girl received a peripheral blood stem cell transplant for relapsed acute lymphoblastic leukaemia. The post-transplant period was uneventful and a course of intrathecal chemotherapy was given on Day-30. On Day-41, she developed acute encephalopathy with diplopia and nystagmus. She ran a rapid downhill course and succumbed despite antiviral treatment. The only positive pathological finding was the multiple microscopic foci of haemorrhage associated with neuronal degeneration detected in the brain stem. All microbiological investigations were negative, except for the presence of HHV-7 DNA in cerebrospinal fluid and brain stem tissue samples., (Copyright 2002 Wiley-Liss, Inc.)

An influenza B virus, B/Saga/S172/99 (SAG99), was isolated from the nasopharynx of a patient with encephalopathy/encephalitis in Japan in 1999. To clarify the molecular characteristics of this virus, detailed analysis of the gene segments coding for the hemagglutinin (HA), neuraminidase (NA), nucleoprotein (NP), matrix protein (M) and non-structural protein (NS) was undertaken. All five genes of SAG99 showed high nucleotide and predicted amino acid similarities with those of recent non-encephalopathic strains isolated in the same epidemic season. Subsequent phylogenetic analysis revealed that all five gene segments of SAG99 analyzed in the present study were most similar to those of the recent Yamagata/16/88-like viruses. The hemagglutinin and neuraminidase proteins of SAG99 were each distinguished from those of recent epidemic strains by one characteristic amino acid substitution. These substitutions were not found in the previously reported encephalopathy/encephalitis-derived influenza B viruses, and we could not find any common characteristic amino acid changes in SAG99 and these viruses. Similarly, among the internal proteins studied, only the M2 protein of SAG99 was found to contain a single novel amino acid change when compared with other recent isolates. Thus, it was apparent that SAG99 contained very few amino acid differences when compared with other epidemic viruses. The association of recent B/Yamagata/16/88-like viruses with encephalitis/encephalopathy observed in the present study and previously suggest that these viruses may have a higher potential for causing neurological complications in certain individuals., (Copyright 2001 Wiley-Liss, Inc.)

Central nervous system complications are common in stem cell transplant recipients, but selective involvement of the medial temporal area is unusual. The 5 patients reported here presented after stem cell transplantation with increased hippocampal T2 signal on magnetic resonance imaging and increased hippocampal glucose uptake on [F-18]fluorodeoxyglucose-positron emission tomography (FDG-PET) associated with short-term memory loss, insomnia, and temporal lobe electrographic seizure activity. The initial scalp electroencephalograms (EEGs) failed to detect seizure activity in these patients, although the memory dysfunction along with the magnetic resonance imaging and FDG-PET findings suggested subcortical seizure activity. However, extended EEG monitoring revealed repetitive temporal lobe electrographic seizure activity. Follow-up MRIs in 2 patients and postmortem findings on 1 patient suggested that hippocampal sclerosis had developed following the clinical syndrome. Cerebrospinal fluid studies revealed the presence of human herpesvirus 6, variant B, DNA in all of 3 patients who had lumbar punctures. Immunohistochemical staining for the P41 and P101 human herpesvirus 6 protein antigens showed numerous immunoreactive astrocytes and neurons in the hippocampus of 1 of the patients who died from other causes. Because of its subtle clinical presentation, this syndrome may be underrecognized, but can be diagnosed with appropriate magnetic resonance imaging techniques, EEG monitoring, and cerebrospinal fluid viral studies.

A fatal case is reported of encephalitis in an 85-year-old man caused by the human herpesvirus 6 variant A. The virological diagnosis was based on the findings of the virus variant genomic sequences both in the cerebrospinal fluid and serum of the patient. Moreover, virus replication in nervous tissue was suggested by a viral load higher in the cerebrospinal fluid than in the peripheral blood. The association of a central nervous system infection with the A variant of human herpesvirus 6 is interesting because of the difficulty in establishing a pathological role for this virus strain. Epstein-Barr virus DNA was detected in the patient's cerebrospinal fluid in association with human herpesvirus 6 DNA. The presence of the Epstein-Barr virus genomic sequences in the cerebro-spinal fluid was considered to be unimportant clinically., (Copyright 2001 Wiley-Liss, Inc.)

Nipah virus, a newly identified paramyxovirus caused a severe outbreak of encephalitis in Malaysia with high fatalities. We report an open-label trial of ribavirin in 140 patients, with 54 patients who were managed prior to the availability of ribavirin or refused treatment as control. There were 45 deaths (32%) in the ribavirin arm; 29 deaths (54%) occurred in the control arm. This represents a 36% reduction in mortality (p = 0.011). There was no associated serious side effect. This study suggests that ribavirin is able to reduce the mortality of acute Nipah encephalitis.

In a two-centre study, the routine DNA preparation and PCR amplification protocols were compared for herpes simplex virus (HSV) detection in cerebrospinal fluids (CSFs) of 43 patients with suspected herpes simplex encephalitis (HSE). The combined clinical, radiological and laboratory results indicated HSE in 6/43 (14%) patients. Discrepant PCR results between the two centres were obtained in 8 (18%) cases consisting of 5 false-positive and 3 false-negative results. Seven out of 8 (88%) discrepant results were associated with the method of CSF preparation using protease K digestion followed by heat inactivation. In contrast, CSF digestion with proteinase K followed by DNA purification on silica spin columns was better yielding discrepant PCR results in only 1 of 78 analyses (1.3%). The results point to the need for standardization and inter-laboratory quality control for routine clinical work.

The incidence of herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) in herpes simplex encephalitis (HSE) was investigated using cerebrospinal fluid (CSF) samples from sixty-four cases of HSE. A polymerase chain reaction (PCR) employing primers flanking a region of the HSV thymidine kinase gene common to both HSV-1 and HSV-2 was used to detect HSV in the CSF. HSV-1 and HSV-2 were differentiated by digestion with restriction enzymes. Two enzymes were employed; Aval which cleaved only the HSV-2 gene product and Avall which cleaved only the HSV-1 gene product. Sixty-three cases of HSE were found to be due to HSV-1; one case due to HSV-2. These data confirm previous observations that HSV-2 is a rare cause of post-neonatal herpes encephalitis but indicates that a PCR procedure capable of detection of both viruses is essential for efficient diagnosis of HSE.

Intracerebral infection of rats with JHM coronavirus induces a chronic inflammatory demyelinating disease, which in many respects mimicks the pathology of multiple sclerosis. We investigated the patterns of demyelination and oligodendrocyte pathology in this model. In early stages of the disease infection of oligodendrocytes was associated with a downregulation of expression of mRNA for proteolipid protein in the absence of myelin destruction. When demyelinating lesions were formed infected oligodendrocytes were destroyed by necrosis, whereas oligodendrocytes that did not contain detectable virus antigen or RNA were in part dying by apoptosis. At this stage of the disease remyelination of the lesions was pronounced. At later stages after infection virus antigen was nearly completely cleared from the lesions. In spite of the lack of detectable virus, ongoing demyelination and unspecific tissue destruction occurred, and oligodendrocytes were mainly destroyed by apoptosis. These late lesions revealed only minimal central remyelination, but they were frequently repaired by Schwann cells. Our studies suggest that the mechanisms of myelin destruction in this model of virus-induced demyelination are complex and that the patterns of tissue damage may change during the course of the disease.

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.

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.

Five cases of apparent relapse of herpes encephalitis were investigated. All patients recovered after antiviral and corticosteroid therapy. Samples of CSF taken from the patients at intervals through the initial and subsequent encephalitic episode were examined. PCR amplification of a 351 bp sequence from the Herpesvirus simplex (HSV) thymidine kinase gene demonstrated the presence of HSV DNA in CSF taken during the initial encephalitic illness but not during the second encephalitic episode. Intrathecal synthesis of HSV antibody (HSV antibody index > 1.9) was observed in all cases following the first episode, and there appeared to be no significant increase in intrathecal antibody synthesis in the second episode. High levels of CSF myelin basic protein were found during the acute phases of both the initial and the subsequent encephalitic illnesses. These data suggest that at least in our series of five patients, relapse following HSE may not be due to active viral replication.

A mixture of adenoviruses 31 and 49 was isolated from the brain of an AIDS patient with encephalitis. Adenovirus hexon protein was detected in neurons by indirect immunofluorescence. By restriction endonuclease analysis both adenovirus 31 and 49 were shown to be new genotypes. This is the first report of the isolation of a mixture of adenoviruses from adenovirus encephalitis and the first association of adenovirus 49, a new candidate serotype, with encephalitis.

Human cytomegalovirus (HCMV) is one of the major pathogens causing neurologic disease in the immunocompromised host. A competitive nested polymerase chain reaction (PCR) was used to determine DNA load, distribution, and sequence variability of HCMV genomes in the brain of AIDS patients with and without HCMV encephalitis confirmed by histology and immunocytochemistry. By quantitative PCR, HCMV genomes were found to be distributed diffusely in the central nervous system (CNS) of all five patients with histologically proven HCMV encephalitis, but also in the brain of five of eight AIDS patients without neuropathological evidence of HCMV encephalitis. The viral DNA load in cases with HCMV encephalitis was increased 10- to 1,000-fold as compared to patients without evidence of encephalitis. A viral load above 6,000 copies HCMV/10(6) copies beta-globin was found to be highly suggestive for HCMV encephalitis. Characterization of PCR products by temperature gradient gel electrophoresis (TGGE) and direct sequencing allowed us to detect a sequence variability of the amplified fragment of HCMV glycoprotein B (gB) among different patients, but also among different HCMV foci within the same patient. Furthermore, two of five AIDS patients with HCMV encephalitis most likely experienced double infections with different HCMV strains. The experimental procedure described in this study should also be applicable to the detection of significant HCMV DNA levels in biopsy samples.

Self-limited involvement of the central nervous system (CNS) is a relatively common complication of primary infection with human herpesvirus six (HHV-6) in normal children. We describe an HIV-infected infant who developed fulminant encephalitis as a complication of HHV-6 infection. Immunohistochemical staining of CNS tissue demonstrated productive infection of all CNS cell-types. Analysis of the infected brain tissue by the polymerase chain reaction (PCR) confirmed the presence of a dense HHV-6 infection in the tissue, and demonstrated that the virus present in the CNS tissue was predominantly the A variant of HHV-6. This is the first demonstration of invasive tissue disease caused by HHV-6 in an HIV-infected infant.