Chronic Dengue Virus Panencephalitis in a Patient with Progressive Dementia with Extrapyramidal Features

Abstract

Objective: To determine the underlying etiology in a patient with progressive dementia with extrapyramidal signs and chronic inflammation referred to the National Institutes of Health Undiagnosed Diseases Program.

Methods: Extensive investigations included metabolic profile, autoantibody panel, infectious etiologies, genetic screening, whole exome sequencing, and the phage-display assay, VirScan, for viral immune responses. An etiological diagnosis was established postmortem.

Results: Using VirScan, enrichment of dengue viral antibodies was detected in cerebrospinal fluid as compared to serum. No virus was detected in serum or cerebrospinal fluid, but postmortem analysis confirmed dengue virus in the brain by immunohistochemistry, in situ hybridization, quantitative polymerase chain reaction, and sequencing. Dengue virus was also detectable by polymerase chain reaction and sequencing from brain biopsy tissue collected 33 months antemortem, confirming a chronic infection despite a robust immune response directed against the virus. Immunoprofiling and whole exome sequencing of the patient did not reveal any immunodeficiency, and sequencing of the virus demonstrated wild-type dengue virus in the central nervous system.

Interpretation: Dengue virus is the most common arbovirus worldwide and represents a significant public health concern. Infections with dengue virus are usually self-limiting, and chronic dengue infections have not been previously reported. Our findings suggest that dengue virus infections may persist in the central nervous system causing a panencephalitis and should be considered in patients with progressive dementia with extrapyramidal features in endemic regions or with relevant travel history. Furthermore, this work highlights the utility of comprehensive antibody profiling assays to aid in the diagnosis of encephalitis of unknown etiology. ANN NEUROL 2019;86:695-703.

FIGURE 1:

Clinical and histopathological findings. (A) Time line shows the patient’s progressive neurological decline over 7 years following multiple trips to India. His clinical course was unaffected by immunomodulatory therapy for presumed autoimmune encephalitis. (B) T2-weighted axial images, acquired 3 years apart, demonstrate a dramatic widening of third and lateral ventricles and worsening atrophy of the sulci. An increase in iron in basal ganglia (T2 hypointensity) is also apparent. (C) Histopathological findings on brain biopsy reveal perivascular infiltrates (upper left) and microglial nodules (upper right). Immunostaining for astrocytes with clinical antibody to glial fibrillary acid protein (GFAP) shows diffuse reactive astrocytosis. Immunostaining for CD3, a pan-T-cell marker, shows focal infiltrates that are largely composed of CD8⁺ T cells. No CD20⁺ B cells were observed.

FIGURE 2:

Detection of dengue virus (DENV) infection in the central nervous system by VirScan. (A, C) Scatterplot comparing abundance of ~96,000 phage-displayed VirScan peptides in cerebrospinal fluid (CSF; y-axis) versus serum (x-axis) immunoprecipitates. Normalized sequencing read counts are plotted as reads per million on log-log axes. Robust linear regression was used to determine which peptides were significantly enriched by CSF antibodies relative to serum antibodies (blue circles). Of the peptides relatively enriched by CSF antibodies, those representing DENV (A) and Japanese encephalitis virus (JEV; C) are marked in red. (B, D) Graph of z scores (y-axis) of viral peptides (x-axis) immunoprecipitated by antibodies from CSF. All peptides with a z score >20 were plotted. Peptides derived from DENV (B) or JEV (D) are marked with a solid red circle, and those from other viruses are marked with an open black circle.

FIGURE 3:

Detection of dengue virus (DENV) in the central nervous system. (A) Quantitative polymerase chain reaction (PCR) from patient postmortem brain tissue (Patient brain) demonstrates DENV transcripts that are not detected from healthy control brain tissue (Control brain) or patient cerebrospinal fluid (Patient CSF). Both tissues demonstrate equivalent β-actin (endogenous control) transcripts. (B) Photograph of PCR products separated by gel electrophoresis amplified with either DENV-1 or DENV-4 primers. Bands are present in autopsy and biopsy samples amplified with DENV-1-specific primers but not DENV-4-specific primers. Dengue is detectable by PCR from DENV-4-infected organoids by both DENV-1-specific and DENV-4-specific primers. No bands are observed for normal tissue controls (NTC). (C) Chromatograms from dengue viral sequences amplified from biopsy and autopsy tissues. Differences between the two sequences are highlighted in yellow. (D-I) Representative images of immunostaining of hippocampus (D), basal ganglia (F), and cerebellum (H) from autopsy brain tissue with 4G2 antibody. Viral protein expression in cerebral vasculature (arrows in F) and in glial cells (arrowheads in H) was noted in addition to widespread neuronal staining. RNA scope using specific probes for DENV (E, G, I) demonstrates the detection of viral RNA throughout examined regions.