Herpes Simplex Encephalitis Patients Research Articles

Predictors of Neurological Disability at Hospital Discharge for Acyclovir-treated Pediatric Herpes Simplex Virus Encephalitis.

Herpes simplex virus encephalitis (HSE) is a rare but serious neurological infection that causes neurological dysfunction. Research is lacking on the clinical predictors of neurological outcomes and the optimal duration of therapy for pediatric HSE patients. In this study of pediatric HSE patients, we identified factors predicting neurological disability at hospital discharge and examined associations of acyclovir therapy duration with neurological outcomes. This was a retrospective cohort study on 37 children diagnosed with HSE confirmed by polymerase chain reaction at age 1 month to 16 years from 2015 to 2021 in Ho Chi Minh City's Children's Hospital No. 2, Vietnam. For the acyclovir duration analysis, we examined 22 children with negative polymerase chain reaction on day 14 of treatment. Poisson regression was used to obtain the risk ratio and 95% confidence interval. The study population consisted of 73% males, with a median age of 14 months (interquartile range: 9-35). Coma at acyclovir treatment, hypotension and the need for mechanical ventilation ≥48 hours significantly predicted neurological disability in the bivariate analysis. There were no significant associations between acyclovir duration (14 vs. 21 days) and neurological outcomes, adjusting for age at diagnosis and pediatric Glasgow Coma Scale score at acyclovir initiation. We identified significant predictors of neurological disability unaffected by postacyclovir treatment factors. Among patients with negative HSE polymerase chain reaction on day 14, 14 days of acyclovir treatment may be as effective as 21 days. Additional studies on the effects of acyclovir duration are needed.

Herpes simplex encephalitis in France: incidence, 6-month rehospitalizations and mortality.

Herpes simplex encephalitis (HSE) is a disease with unfavorable vital and functional prognoses. There are no recent epidemiological data on HSE at a national level using real-life databases, especially in France. This study aimed to report the incidence, the clinical characteristics and outcomes of the patients with HSE. We conducted a comprehensive retrospective cohort study on all patients hospitalized for HSE in France between 2015 and 2022 using national hospital discharge databases. Incidence, socio-demographic and clinical characteristics (including comorbidities, seizure, stays' features, intensive care supports) were described. The short- (first stay) and long-term (6-month) outcomes were reported, in terms of mortality and rehospitalizations. 1425 HSE patients were included (median age 67 [54-77] years old, M/F sex ratio 1.07), giving a mean yearly hospital incidence of 2.3 [2.1-2.5] per 1,000,000 inhabitants. 51.2% of the patients were admitted in ICU (n = 730), of whom 59.0% were mechanically ventilated. The overall mortality during the first stay was 14.3% (n = 204), up to 17.9% for ICU patients. Within 6months, among the survivors, 10.1% had at least one rehospitalization related to HSE. At 6months, 16.5% of all patients had died (n = 235), 20.8% for ICU patients. In France, the incidence of hospitalizations for HSE was 2.3 per 1,000,000 inhabitants with more than half of the patients admitted in ICU and a 6-month in-hospital mortality about 16.5%. This real-life update on the characteristics and severe outcomes of the disease raises awareness among care practitioners, of the serious nature of the disease, and thus can lead to higher vigilance.

Temporal pathway analysis of cerebrospinal fluid proteome in herpes simplex encephalitis

Objectives We examined the temporal changes of the CSF proteome in patients with herpes simplex encephalitis (HSE) during the course of the disease, in relation to anti-N-methyl-D-aspartate receptor (NMDAR) serostatus, corticosteroid treatment, brain MRI and neurocognitive performance. Methods Patients were retrospectively included from a previous prospective trial with a pre-specified CSF sampling protocol. Mass spectrometry data of the CSF proteome were processed using pathway analysis. Results We included 48 patients (110 CSF samples). Samples were grouped based on time of collection relative to hospital admission – T1: ≤ 9 d, T2: 13–28 d, T3: ≥ 68 d. At T1, a strong multi-pathway response was seen including acute phase response, antimicrobial pattern recognition, glycolysis and gluconeogenesis. At T2, most pathways activated at T1 were no longer significantly different from T3. After correction for multiplicity and considering the effect size threshold, 6 proteins were significantly less abundant in anti-NMDAR seropositive patients compared to seronegative: procathepsin H, heparin cofactor 2, complement factor I, protein AMBP, apolipoprotein A1 and polymeric immunoglobulin receptor. No significant differences in individual protein levels were found in relation to corticosteroid treatment, size of brain MRI lesion or neurocognitive performance. Conclusions We show a temporal change in the CSF proteome in HSE patients during the course of the disease. This study provides insight into quantitative and qualitative aspects of the dynamic pathophysiology and pathway activation patterns in HSE and prompts for future studies on the role of apolipoprotein A1 in HSE, which has previously been associated with NMDAR encephalitis.

Functional brain networks reorganization in the absence of medial temporal lobe structures: an example of neuroplasticity

AbstractBackgroundMedial temporal lobe structures are particularly vulnerable in age‐related neurodegenerative diseases. Here, we investigated the brain reorganization that allows maintaining relatively normal global cognitive functioning in patients with herpes simplex encephalitis (HSE) – an infectious neurological disease ‐ with marked focal atrophy most pronounced in the medial temporal lobes, particularly the hippocampus. Using rs‐fMRI we (i) characterized the patterns of functional network organization, and (ii) compared the intra‐/interhemispheric functional connectivity (FC) within each patient.MethodA total of nine HSE patients were included (see Table 1), four of them were affected mainly in the left (LH) and five in the right (RH) hemisphere. The rs‐fMRI data were acquired after a long‐term follow‐up (median 16 years) of the disease and were preprocessed using the AFNI software. For each patient, using different brain parcellations, we computed the intra‐ and inter‐FC strength for each hemisphere separately, yielding four measures of intra‐FC LH/RH and inter‐FC LH/RH . We grouped the subjects according to their lesion‐side and their performance (low, high) in a memory task.ResultWe observed, regardless of the lesion side, a highly variable pattern of disrupted FC in each patient. Left‐lesioned patients showed high intra‐FCLH/RH particularly in the precuneus/posterior cingulate (PPC) and the angular gyrus while right‐lesioned patients exhibited a high inter‐FCRH in the medial prefrontal cortex (MPFC) and PPC regions. Both left and right‐lesioned showed decreased intra‐FCLH/RH in ventral medial temporal areas, more pronounced in the left‐lesioned patients (Figure1). Right‐lesioned individuals who showed a pattern of inter‐FC within the right MPF and PPC performed consistently higher on the memory task (percentiles > 50) (Figure2).ConclusionThe substantial HSE‐induced medial temporal lobe lesions induce a global network reorganization. However, the side of the lesion seems to determine a specific pattern of network reorganization that is associated with differential cognitive performance. Left‐lesioned patients exhibited high PPC intra‐ and inter‐FCLH/RH and low memory performance while the right‐lesioned exhibited a high inter‐FCRH on the PPC and MPFC and better memory performance. Left lesions may result in nonadaptive brain reorganizations, however, right lesions, when linked to prefrontal brain reorganizations, may result in cognitive benefits and therefore be adaptive.

Association between human genetic variants affecting the host NK cell response and the development of herpes simplex virus type 1 encephalitis.

Herpes simplex virus encephalitis (HSE) is a rare complication of herpes simplex virus type 1 (HSV-1) infection or reactivation. It is so far unclear why only few patients develop HSE. As natural killer (NK) cells provide an important defense against HSV-1, we investigated whether there is an association between distinct human genetic variants associated with the host NK cell response and HSE. Forty-nine adult patients with confirmed HSE and 247 matched controls were analyzed for the distribution of the following genotypes: CD16A (FcγRIIIA) V/F and IGHG1 G1m3/17, both influencing antibody-dependent cellular cytotoxicity; HLA-E*0101/*0103, associated with NK cell activation; and SLFN13 rs9916629C/T associated with NK cell response. Homozygous HLA-E*0101:0101 and HLA-E*0103:0103 variants as well as the rs9916629CC genotype were overrepresented in HSE patients compared to controls (p ≤ 0.001). Notably, cooccurrence of the homozygous HLA-E*0101 and rs9916629CC genotypes was present in 19% of patients but totally absent in controls (p ≤ 0.0001). Distribution of CD16A and IGHG1 variants did not differ between patients and controls. Our data show that the rare combination of HLA-E*0101:0101 and rs9916629CC is significantly associated with HSE. Possibly, these genetic variations could be useful as clinical markers predicting HSE prognosis and helping to adapt the treatment of HSE in the individual patient.

MRI of neurosyphilis with mesiotemporal lobe lesions of "knife-cut sign” on MRI: A case report and literature review

Neurosyphilis with mesiotemporal lobe lesions remains a difficult entity to diagnose, especially when it mimics herpes simplex encephalitis (HSE). Here, we report what appeared to be the first case of mesiotemporal imaging of neurosyphilis presenting as a “knife-cut” sign and mimicking HSE pathological hallmarks on imaging. The magnetic resonance imaging (MRI) changes in neurosyphilis and HSE were indistinguishable in the initial diagnosis because of the common involvement of the mesiotemporal lobe. Neurosyphilis was diagnostically confirmed by positive readings in the treponema pallidum hemagglutination assay (TPHA), rapid plasma reagin (RPR) and cerebrospinal fluid-polymerase chain reaction (CSF-PCR) tests for Treponema pallidum infection. Neurosyphilis and HSE had similar clinical features and signs on MRI, except the knife-cut sign which is a common diagnosis in HSE. Therefore, neurosyphilis with mesiotemporal changes and knife-cut signs on MRI should be evaluated in the differential diagnosis in all patients, as similar changes may also occur in HSE patients. The literature review of published articles between 1997 and 2020 was conducted to further validate our clinical observations and discuss diagnostic and treatment options for neurosyphilis with mesiotemporal lobe lesions.

Cerebrospinal Fluid Extracellular Vesicles with Distinct Properties in Autoimmune Encephalitis and Herpes Simplex Encephalitis

Encephalitis mediated by autoantibodies against neuronal antigens and herpes simplex encephalitis (HSE) are seemingly separate causes of encephalopathy in adults. Autoimmune encephalitis (AE) is autoimmune in origin, and herpes simplex encephalitis is infectious. The purpose of this study was to examine the role of cerebrospinal fluid (CSF) exosomes from patients with antibody-positive AE and HSE. Towards this, exosomes were isolated from CSF from 13 patients with anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis, 11 patients with anti-gamma-aminobutyric acid-B (GABAB) receptor encephalitis, 9 patients with anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis, and 8 patients with anti-contactin-associated protein-like 2 (CASPR2) encephalitis, and 12 control individuals negative of antibodies against neuronal autoantigens. There were ten miRNAs highly expressed in patients with anti-NMDAR encephalitis compared to those in control subjects. Eight miRNAs were found to be lower expressed in anti-NMDAR encephalitis CSF-derived exosomes. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enriched by AE differential expressed exosomic miRNAs demonstrated that AE-related exosomic miRNAs may participate as a feedback regulation in cancer development. In addition, the exosome concentration in CSF of 9 HSE patients was significantly higher compared to those from 9 HSV( −) patients. This observation was consistent with the results that exosome concentration was found to be higher in the animal model which was inoculated intranasally with HSV-1 compared to controls. Furthermore, western blot demonstrated that the subunits of NMDAR, GABABR, and AMPAR were detected highly expressed in exosomes derived from sera of HSV-1-treated animal model compared to controls. More importantly, exosomes isolated from CSF of HSE patients contained higher expression levels of two miRNAs encoded by HSV, miR-H2-3p, and miR-H4-3p compared to those from HSV( −) patients. In summary, HSV may trigger brain autoimmunity in HSE by presentation of surface autoantigens via exosomes.

Cerebrospinal fluid biomarkers of brain injury, inflammation and synaptic autoimmunity predict long-term neurocognitive outcome in herpes simplex encephalitis

ObjectivesThe aim was to investigate the correlation between biomarkers of brain injury and long-term neurocognitive outcome, and the interplay with intrathecal inflammation and neuronal autoimmunity, in patients with herpes simplex encephalitis (HSE). MethodsA total of 53 adult/adolescent HSE patients were included from a prospective cohort in a randomized placebo-controlled trial investigating the effect of a 3-month follow-up treatment with valaciclovir. Study subjects underwent repeated serum/cerebrospinal fluid (CSF) sampling and brain magnetic resonance imaging in the first 3 months along with cognitive assessment using the Mattis Dementia Rating Scale (MDRS) at 24 months. CSF samples were analysed for biomarkers of brain injury, inflammation and synaptic autoimmunity. The predefined primary analysis was the correlation between peak CSF neurofilament protein (NFL), a biomarker of neuronal damage, and MDRS at 24 months. ResultsImpaired cognitive performance significantly correlated with NFL levels (rho = –0.36, p = 0.020). Development of IgG anti-N-methyl-D-aspartate receptor (NDMAR) antibodies was associated with a broad and prolonged proinflammatory CSF response. In a linear regression model, lower MDRS at 24 months was associated with previous development of IgG anti-N-methyl-D-aspartate receptor (NMDAR) (beta = –0.6249, p = 0.024) and age (z-score beta = –0.2784, p = 0.024), but not CSF NFL, which however significantly correlated with subsequent NMDAR autoimmunization (p = 0.006). DiscussionOur findings show that NFL levels are predictive of long-term neurocognitive outcome in HSE, and suggest a causative chain of events where brain tissue damage increases the risk of NMDAR autoimmunisation and subsequent prolongation of CSF inflammation. The data provides guidance for a future intervention study of immunosuppressive therapy administered in the recovery phase of HSE.

Acute retinal necrosis following herpes simplex encephalitis: a nationwide survey in Japan.

Acute retinal necrosis (ARN) is a severe necrotizing retinitis caused by varicella-zoster virus or herpes simplex virus (HSV) that often results in blindness. Occasionally, HSV-caused ARN develops after herpes simplex encephalitis (HSE). It remains unknown, however, when and how often ARN develops after HSE. To investigate the actual conditions of patients with ARN following HSE and the interval period between the prior HSE and the onset of ARN, a retrospective nationwide survey of the Japanese population was performed. Retrospective. Questionnaires were sent out to the neurology and ophthalmology departments of teaching hospitals in Japan. They inquired about HSE patients in neurology departments and ARN patients diagnosed with HSV in ophthalmology departments. The proportion of the HSV-ARN patients with a history of HSE and their interval periods were obtained from the questionnaires returned by the ophthalmology departments. Neurology departments of 324 hospitals responded to the questionnaires (response proportion: 40.9%), and 53 HSE cases were reported. Ophthalmology departments of 535 hospitals responded the questionnaires (response proportion: 54.3%), and 67 HSV-ARN cases were reported. Among the 67 HSV-ARN cases, 16 (23.9%) had histories of prior HSE. Although the interval periods from the prior HSE to the onset of HSV-ARN varied among cases, nearly half developed HSV-ARN within 2 years. This nationwide survey of the Japanese population showed that HSV-ARN develops after HSE in higher frequency within 2 years. Neurologists and ophthalmologists should be aware that HSE survivors have a risk of contracting HSV-ARN.

Decompressive craniectomy for herpes simplex encephalitis complicated by frank intracerebral hemorrhage: a case report and review of the literature

BackgroundHerpes simplex encephalitis is the most common type of sporadic encephalitis worldwide. Frank intracerebral hemorrhage complicating the disease course in herpes simplex encephalitis patients is rare, especially cases where surgical decompression is necessary. Here, we report a previously healthy female with herpes simplex encephalitis who underwent surgical decompression due to temporal lobe hemorrhage.Case presentationA previously healthy 34-year-old Korean female presented with fever, myalgia and severe headache. Brain MRI showed a high T2 signal intensity change and diffuse swelling of the right temporal lobe. Polymerase chain reaction testing of the cerebrospinal fluid confirmed the presence of herpes simplex virus 1. The patient was admitted for close observation and intravenous acyclovir. On hospital day 3, she had a sudden onset of vomiting and severe headache. Brain CT showed frank temporal lobe hemorrhage. Despite aggressive medical treatment, she became increasingly drowsy. Ultimately, she underwent emergency right decompressive craniectomy, expansile duraplasty and intracranial pressure monitor insertion. The patient recovered fully without any neurological deficits or neuropsychological problems. She was discharged after completion of 2 weeks of acyclovir and returned 2 months later for cranioplasty.ConclusionsPatients with severe herpes simplex encephalitis complicated by intracerebral hemorrhage or malignant cerebral edema should undergo aggressive medical treatment. Surgical decompression should also be actively considered in these severe cases to prevent further neurological deterioration.

Increased level of compleasomes in cerebrospinal fluid of patients with herpes simplex encephalitis

Herpes simplex encephalitis (HSE) is a common cause of viral encephalitis (HSV-1) characterised by pronounced inflammation and elevated intracranial pressure. We have shown in a rat model that HSV-1 infection causes an interaction between complement factors and proteasomes, leading to formation of proteasome/complement complexes (compleasomes). Exposure of the proteasome regulatory subunit antisecretory factor 1 (AF1) leads to a decrease in intracranial pressure. The aim of this study was to evaluate the acute and prolonged formation of compleasomes in cerebrospinal fluid (CSF) from patients with HSE. Cerebrospinal fluid samples (n = 55) from 24 HSE patients were analysed for compleasome complexes. Samples from healthy controls (n = 23) and patient controls (n = 27) served as baseline information. Sandwich enzyme-linked immunosorbent assay (ELISA) for proteasomes and their complex formation with complement factor 3 or 4, and Western blot for C3 activation were performed on CSF samples. Increased compleasome formation, both presenting as an initial formation and showing exposure of subunit AF1 in the compleasomes, was found in CSF samples drawn from patients with HSE compared with samples from the control groups (p < 0.0005). The total protein CSF concentration was equal in all groups. The levels were higher in the acute phase compared with late in the disease course (p < 0.0005). Complement 3 breakdown product iC3b was detected in CSF samples of the HSE patients. The early increased formation of compleasomes in CSF suggests that this complex may be involved in host defence against HSE.

Acyclovir Sensitivity and Neurovirulence of Herpes Simplex Virus Type 1 with Amino Acid Substitutions in the Viral Thymidine Kinase Gene, Which Were Detected in the Patients with Intractable Herpes Simplex Encephalitis Previously Reported.

Several cases of herpes simplex encephalitis (HSE) caused by acyclovir (ACV)-resistant herpes simplex virus type 1 (HSV-1) have been reported. Amino acid substitutions of R41H, Q125H, and A156V in the viral thymidine kinase (vTK) gene have been reported to confer ACV resistance. Recombinant HSV-1 clones, containing each amino acid substitution in the vTK gene, were generated using the bacterial artificial chromosome system. A recombinant HSV-1 with the Q125H substitution showed ACV resistance while the R41H or A156V substitutions were ACV-sensitive. Furthermore, the Q125H recombinant HSV-1 was less virulent than the repaired virus, but it maintained neurovirulence in mice at relatively high levels. Substitution of Q125H, which was detected in the neonatal HSE patient, conferred ACV resistance, but the substitutions of R41H and A156V, which were detected in immunocompetent adult HSE patients, did not. This suggests that HSE caused by ACV-resistant HSV-1 might be a very rare event to occur during the course of ACV treatment in immunocompetent patients. Showing resistance to ACV treatment does not always indicate emergence of ACV-resistant HSV-1 in HSE patients.

Recall of semantically related word-lists in two patients with herpes simplex encephalitis

ObjectiveThe aim of the present study is to provide further insight into semantic processing in Working Memory (WM) in two amnesic patients with extensive medial temporal lobe (MTL) by adopting a short length word-lists recall task. BackgroundIt is still unclear whether the medial temporal lobe structures and especially the hippocampus is recruited in semantic processing in the context of WM. Materials & methodsTwo severely amnesic patients with extensive MTL damage due to herpes simplex encephalitis (HSE) and a control group (n=36) underwent an experimental task involving the immediate free recall of 9 word-lists in three different conditions: 1. semantically related words clustered according to semantic category (SRC), 2. semantically related words non-clustered (SRnC), 3. semantically unrelated words (SU). Additionally, standard cognitive measures were administered [Digit Span Forward & Backward, Greek Verbal Learning Test (GVRT), Verbal Fluency Test (VFT), Logical Memory I & II (LM-I & LM-II) of Wechsler Memory Scale (WMS)]. ResultsBoth patients obtained normal performance in WM tests (Digit Span Forward & Backward), but were impaired in GVRT, VFT, LM-I and LM-II. With regard to the word-list task, the number of words recalled by both patients’ did not differ from controls. However, semantic facilitation effects were not recorded in patients’ performance for the SRC and SRnC conditions (SRC=SRnR=SU), unlike controls (SRC>SRnC>SU). ConclusionsOur results suggest that the effects of semantic facilitation in short length word-lists recall are diminished to a certain degree in HSE patients that suffer from MTL damage.

Resident T Cells Are Unable To Control Herpes Simplex Virus-1 Activity in the Brain Ependymal Region during Latency.

HSV type 1 (HSV-1) is one of the leading etiologies of sporadic viral encephalitis. Early antiviral intervention is crucial to the survival of herpes simplex encephalitis patients; however, many survivors suffer from long-term neurologic deficits. It is currently understood that HSV-1 establishes a latent infection within sensory peripheral neurons throughout the life of the host. However, the tissue residence of latent virus, other than in sensory neurons, and the potential pathogenic consequences of latency remain enigmatic. In the current study, we characterized the lytic and latent infection of HSV-1 in the CNS in comparison with the peripheral nervous system following ocular infection in mice. We used RT-PCR to detect latency-associated transcripts and HSV-1 lytic cycle genes within the brain stem, the ependyma (EP), containing the limbic and cortical areas, which also harbor neural progenitor cells, in comparison with the trigeminal ganglia. Unexpectedly, HSV-1 lytic genes, usually identified during acute infection, are uniquely expressed in the EP 60 d postinfection when animals are no longer suffering from encephalitis. An inflammatory response was also mounted in the EP by the maintenance of resident memory T cells. However, EP T cells were incapable of controlling HSV-1 infection ex vivo and secreted less IFN-γ, which correlated with expression of a variety of exhaustion-related inhibitory markers. Collectively, our data suggest that the persistent viral lytic gene expression during latency is the cause of the chronic inflammatory response leading to the exhaustion of the resident T cells in the EP.

N-methyl-d-aspartate receptor autoimmunity affects cognitive performance in herpes simplex encephalitis

ObjectivesTo investigate the prevalence and temporal development of N-methyl-d-aspartate receptor (NMDAR) autoantibodies in relation to neurocognitive performance in patients with herpes simplex encephalitis (HSE). MethodsThis prospective observational study enrolled a total of 49 HSE patients within a randomized controlled trial of valacyclovir. Cerebrospinal fluid and serum samples were drawn in the initial stage of disease, after 2 to 3 weeks and after 3 months. Anti-NMDAR IgG was detected with HEK293 cells transfected with plasmids encoding the NMDA NR1 type glutamate receptor. A batch of neurocognitive tests, including the Mattis Dementia Rating Scale (MDRS), Glasgow Coma Scale (GCS), Reaction Level Scale (RLS85), Mini-Mental State Examination (MMSE) and National Institutes of Health (NIH) stroke scale, was performed during 24 months' follow-up. ResultsAnti-NMDAR IgG was detected in 12 of 49 participants. None were antibody positive in the initial stage of disease. In ten of 12 positive cases, specific antibodies were detectable only after 3 months. Notably, the development of NMDAR autoantibodies was associated with significantly impaired recovery of neurocognitive performance. After 24 months' follow-up, the median increase in MDRS total score was 1.5 vs. 10 points in antibody-positive and -negative participants (p=0.018). ConclusionsAnti-NMDAR autoimmunity is a common complication to HSE that develops within 3 months after onset of disease. The association to impaired neurocognitive recovery could have therapeutical implications, as central nervous system autoimmunity is potentially responsive to immunotherapy.

Prevalence of Intrathecal Acyclovir Resistant Virus in Herpes Simplex Encephalitis Patients.

Herpes simplex encephalitis (HSE) is a life-threatening complication of herpes simplex virus (HSV) infection. Acyclovir (ACV) is the antiviral treatment of choice, but may lead to emergence of ACV-resistant (ACVR) HSV due to mutations in the viral UL23 gene encoding for the ACV-targeted thymidine kinase (TK) protein. Here, we determined the prevalence of intrathecal ACVR–associated HSV TK mutations in HSE patients and compared TK genotypes of sequential HSV isolates in paired cerebrospinal fluid (CSF) and blister fluid of mucosal HSV lesions. Clinical samples were obtained from 12 HSE patients, encompassing 4 HSV type 1 (HSV-1) and 8 HSV-2 encephalitis patients. HSV DNA load was determined by real-time PCR and complete HSV TK gene sequences were obtained by nested PCR followed by Sanger sequencing. All HSV-1 HSE patients contained viral TK mutations encompassing 30 unique nucleotide and 13 distinct amino acid mutations. By contrast, a total of 5 unique nucleotide and 4 distinct amino acid changes were detected in 7 of 8 HSV-2 patients. Detected mutations were identified as natural polymorphisms located in non-conserved HSV TK gene regions. ACV therapy did not induce the emergence of ACVR-associated HSV TK mutations in consecutive CSF and mucocutaneous samples of 5 individual patients. Phenotypic susceptibility analysis of these mucocutaneous HSV isolates demonstrated ACV-sensitive virus in 2 HSV-1 HSE patients, whereas in two HSV-2 HSE patients ACVR virus was detected in the absence of known ACVR-associated TK mutations. In conclusion, we did not detect intrathecal ACVR-associated TK mutations in HSV isolates obtained from 12 HSE patients.

A study on viral CNS inflammation beyond herpes encephalitis.

The early diagnosis of herpes simplex virus encephalitis (HSVE) enables induction of antiviral therapy in this potentially life-threatening disease. The study aimed to determine clinical findings including cerebrospinal fluid (CSF) data and MRI imaging in HSVE patients and to identify features distinguishing HSVE from encephalitis of other viral etiologies. We retrospectively reviewed consecutive patients who were diagnosed with viral encephalitis between 2000 and 2014 at the University Hospital Halle. Forty-nine patients with viral encephalitis were identified. A viral etiology could be confirmed by PCR or antibody testing in 22/49 (44.9%) of patients (15 (30.6%) HSV, 5 (10.2%) VZV, 2 (4.1%) EBV). In HSVE, typical findings were focal slowing in electroencephalophy (EEG) (80%, p = 0.021) and presence of cortical (86.7%, p = 0.030) lesions in MRI. Restricted diffusion was particularly helpful in detection of early signal abnormalities in HSVE (p = 0.014). In 27/49 (55.1%) of patients, no causative agent could be elucidated. In these patients, 15/27 (55.6%) experienced a rather "benign" disease course with no MRI pathology despite initially HSVE mimicking clinical picture. However, CSF was significantly different showing a higher amount of granulocytes and activated lymphocytes. The remaining 12/27 (44.4%) patients developed MRI changes consistent with encephalitis, in 4 of these patients, disease course was fatal. Beside PCR-based serology as standard procedure, MRI including diffusion-weighted images and EEG represent additional tools in early HSVE diagnosis. CSF cytology might be particularly supportive in differentiating likely benign forms of encephalitis.

Acute and prolonged complement activation in the central nervous system during herpes simplex encephalitis

Herpes simplex encephalitis (HSE) is characterized by a pronounced inflammatory activity in the central nervous system (CNS). Here, we investigated the acute and prolonged complement system activity in HSE patients, by using enzyme-linked immunosorbent assays (ELISAs) for numerous complement components (C). We found increased cerebrospinal fluid concentrations of C3a, C3b, C5 and C5a in HSE patients compared with healthy controls. C3a and C5a concentrations remained increased also compared with patient controls. Our results conclude that the complement system is activated in CNS during HSE in the acute phase, and interestingly also in later stages supporting previous reports of prolonged inflammation.

Normocellular CSF in herpes simplex encephalitis.

BackgroundHerpes simplex virus (HSV) is the most common cause of sporadic encephalitis worldwide. The high mortality rate (70–80 %) of herpes simplex encephalitis (HSE) can be reduced to 20–30 % by antiviral therapy. However, normocellular CSF can lure physicians to look for non-infectious causes, resulting in delayed treatment. This study aimed to investigate, characterize and differentiate HSE patients, with normocellular and pleocytosis CSF, according to neuroimaging patterns, underlying disease, CSF viral load and clinical outcome. Patients with proven (by PCR positive CSF) or presumed viral infections of the CNS admitted to King Chulalongkorn Memorial Hospital between January 2002 and 2011 were analyzed.ResultsHSV was detected in the CSF of 43 patients but only 23 patients had encephalitis. Among these 23 patients, 6 cases (26.1 %) had normal CSF WBC (<5 cells/mm3). One patient in this normocellular CSF group had HIV infection. Although this patient had low CD4 counts (<200 cells/mm3), the peripheral WBC counts showed only mild leukopenia. The CSF HSV viral load in the pleocytosis group was higher than the normocellular group, with an average of 12,200 vs 3027 copies/ml respectively. There was no correlation between the viral load and the clinical outcome. With respect to neuroimaging, 4 (66.7 %) patients in the normocellular group had unremarkable/non-specific results.ConclusionsNormocellular CSF in HSE is not rare, and can be seen in normal as well as immunocompromised hosts. Clinicians should not exclude CNS infection, especially HSE, merely based on the absence of CSF pleocytosis and/or unremarkable neuroimaging study.

Diagnosis of Herpes Simplex Encephalitis by ELISA Using Antipeptide Antibodies Against Type-Common Epitopes of Glycoprotein B of Herpes Simplex Viruses

Herpes simplex encephalitis (HSE) represents one of the most severe infectious diseases of the central nervous system (CNS). As effective antiviral drugs are available, an early, rapid, and reliable diagnosis has become important. The objective of this article was to develop a sensitive ELISA protocol for herpes simplex viruses (HSV) antigen detection and quantitation by assessing the usefulness of antipeptide antibodies against potential peptides of HSV glycoprotein B (gB). A total of 180 cerebrospinal fluid (CSF) samples of HSE and non-HSE patients were analyzed using a panel of antipeptide antibodies against synthetic peptides of HSV glycoprotein gB. The cases of confirmed and suspected HSE showed 80% and 51% positivity for antipeptide against synthetic peptide QLHDLRF and 77% and 53% positivity for antipeptide against synthetic peptide MKALYPLTT, respectively for the detection of HSV antigen in CSF. The concentration of HSV antigen was found to be higher in confirmed HSE as compared to suspected HSE group and the viral load correlated well with antigen concentration obtained using the two antipeptides in CSF of confirmed HSE group. This is the first article describing the use of antibodies obtained against synthetic peptides derived from HSV in diagnostics of HSE using patients’ CSF samples.