The spectrum of anti-GQ1B antibody syndrome: beyond Miller Fisher syndrome and Bickerstaff brainstem encephalitis.

INTRODUCTION: Since the initial identification of Miller Fisher syndrome (MFS) and Bickerstaff brainstem encephalitis (BBE),significant milestones have been achieved in understanding these diseases.Discoveries of common serum antibodies (IgG anti-GQ1b), antecedent infections, neurophysiological data, andneuroimaging suggested a shared autoimmune pathogenetic mechanism rather than distinct pathogenesis, leadingto the hypothesis that both diseases are part of a unified syndrome, termed "Fisher-Bickerstaff syndrome". The subsequent identification of atypical anti-GQ1b-positive forms expanded the classification to a broader condition known as "Anti-GQ1b-Antibody syndrome". METHODS: An exhaustive literature review was conducted, analyzing a substantial body of research spanning from the initialdescriptions of the syndrome's components to recent developments in diagnostic classification and researchperspectives. RESULTS: Anti-GQ1b syndrome encompasses a continuous spectrum of conditions defined by a common serological profilewith varying degrees of peripheral (PNS) and central nervous system (CNS) involvement. MFS and BBE represent theopposite ends of this spectrum, with MFS primarily affecting the PNS and BBE predominantly involving the CNS.Recently identified atypical forms, such as acute ophthalmoparesis, acute ataxic neuropathy withoutophthalmoparesis, Guillain-Barré syndrome (GBS) with ophthalmoparesis, MFS-GBS and BBE-GBS overlap syndromes,have broadened this spectrum. CONCLUSION: This work aims to provide an extensive, detailed, and updated overview of all aspects of the anti-GQ1b syndromewith the intention of serving as a stepping stone for further shaping thereof. Special attention was given to therecently identified atypical forms, underscoring their significance in redefining the boundaries of the syndrome.

Regulatory mechanism for the human glioblastoma cell-specific expression of the human GD1c/GT1a/GQ1b synthase (hST8Sia V) gene.

In this study we observed that human GD1c/GT1a/GQ1b synthase (hST8Sia V) is particularly expressed in human glioblastoma cells. To address the mechanism regulating human glioblastoma-specific gene expression of the hST8Sia V, after the transcription start site (TSS) was identified by the 5'-rapid amplification of cDNA end with total RNA from human glioblastoma U87MG cells, the 5'-flanking region (2.5 kb) of the hST8Sia V gene was isolated and its promoter activity was examined. By luciferase reporter assay, this 5'-flanking region revealed strong promoter activity in only U-87MG cells, but not in other tissue-derived cancer cells. 5'-deletion mutant analysis showed that the region from -1140 to -494 is crucial for transcription of the hST8Sia V gene in U87MG cells. This region contains the activator protein-1 (AP-1) binding site, the main target of the c-Jun N-terminal kinase (JNK) downstream. The AP-1 binding site at -1043/-1037 was proved to be indispensable for the hST8Sia V gene-specific expression in U87MG cells by site-directed mutagenesis. Moreover, the transcriptional activation of hST8Sia V gene in U87MG cells was strongly inhibited by a specific JNK inhibitor, SP600125. These results suggest that the hST8Sia V gene-specific expression in U87MG cells is controlled by JNK/AP-1 signaling pathway.

Atypical anti-GQ1b antibody syndrome presenting with vomiting as the initial symptom: a case report and literature review.

BACKGROUND: Anti-GQ1b antibody syndrome is a rare autoimmune neuropathy, and atypical cases are even more rare, only a few cases have been reported. Anti-GQ1b antibody syndrome is difficult in early diagnosis and prone to misdiagnosis. Generally,in children with anti-GQ1b antibody syndrome,extraocular muscle paralysis is the initial symptom. However, anti-GQ1b antibody syndrome with vomiting as the initial symptom followed by abnormal gait has not been reported. CASE PRESENTATION: We reported a case of anti-GQ1b antibody syndrome with vomiting as the initial symptom, followed by abnormal gait. One day after vomiting, the child developed abnormal gait, which primarily manifested as a slight tilt of the upper body during walking as well as an opening and swaying of the legs at fast walking paces,then progressively aggravated, and finally he could not stand on his own.In the auxiliary examination, cerebrospinal fluid routine,biochemical and metagenomic Next-Generation Sequencing (DNA and RNA), brain + spinal cord contrast magnetic resonance imaging (MRI),magnetic Resonance angiography (MRA) and diffusion-weighted image (DWI), hip and knee joint ultrasound showed normal results. Anti-GQ1b antibody syndrome was not confirmed until the positive anti-GQ1b IgG antibody was detected in the serum. After treatment with intravenous immunoglobulin (IVIG) and glucocorticoid, the child recovered well, and a 3-month outpatient follow-up showed that the child was able to walk normally. CONCLUSIONS: There are no previous reports of anti-GQ1b antibody syndrome with vomiting as the initial symptom, followed by abnormal gait. Therefore, this valuable case contributes to expanding the database of clinical manifestation of anti-GQ1b antibody syndrome, so as to improve pediatricians' awareness about such rare diseases and reduce misdiagnosis.

A Case of Miller Fisher Syndrome with Cerebellar Hypoperfusion.

We report a case of a 76-year-old man with Miller Fisher syndrome presenting with acute ophthalmoplegia and ataxia. Cerebrospinal fluid analysis showed normocytosis with an increased protein level. Serum anti-GQ1b IgG and anti-GT1a IgG antibodies were positive. Based on these results, the patient was diagnosed with Miller Fisher syndrome. He was treated with two courses of intravenous immunoglobulin, which improved his neurological symptoms. Brain perfusion single-photon emission computed tomography showed that cerebellar blood flow was decreased in the acute stage of the disease and improved after treatment. Although the prevailing view is that ataxia in Miller Fisher syndrome patients is of a peripheral origin, this case suggests that cerebellar hypoperfusion contributes to the development of ataxia in Miller Fisher syndrome.

Ophthalmoplegia associated with anti-GQ1b antibodies: case report and review.

A 60-year-old man with longstanding bilateral asymmetrical ptosis presented with a partial third nerve palsy. His diplopia improved following an ice pack test. He did not report any symptoms related to the coronavirus disease 2019 (COVID-19), and nasopharyngeal swab was negative. Initial head imaging and blood work-up were normal except for a high titer of anti-GQ1b antibodies. The patient was subsequently diagnosed with acute ophthalmoparesis without ataxia which is part of the anti-GQ1b antibody syndrome spectrum. He made a spontaneous recovery over the following months without the need for immunotherapy. Clinical features, pathophysiology and a review of the literature are discussed herein. It is important to consider anti-GQ1b antibody syndrome in patients with symptoms of diplopia, ptosis or suspected ocular myasthenia.

A case of Miller Fisher syndrome with delayed onset peripheral facial nerve palsy after COVID-19 vaccination: a case report.

BACKGROUND: To prevent the spread of the novel coronavirus disease 2019 (COVID-19) infection, various vaccines have been developed and used in a large number of people worldwide. One of the most commonly used vaccines is the mRNA vaccine developed by Moderna. Although several studies have shown this vaccine to be safe, the full extent of its side effects has not yet been known. Miller-Fisher syndrome (MFS) is a rare condition that manifests ophthalmoplegia, ataxia, and loss of tendon reflexes. It is a subtype of Guillain-Barré syndrome and an immune-mediated disease related to serum IgG anti-GQ1b antibodies. Several vaccines including those for COVID-19 have been reported to induce MFS. However, there have been no reports of MFS following Moderna COVID-19 vaccine administration. CASE PRESENTATION: A 70-year-old man was referred to our hospital due to diplopia that manifested 1 week after receiving the second Moderna vaccine dose. The patient presented with restricted abduction of both eyes, mild ataxia, and loss of tendon reflexes. He was diagnosed with MFS based on his neurological findings and detection of serum anti-GQ1b antibodies. The patient was administered intravenous immunoglobulin, and his symptoms gradually improved. Five days after admission, the patient showed peripheral facial paralysis on the right side. This symptom was suggested to be a delayed onset of peripheral facial nerve palsy following MFS that gradually improved by administration of steroids and antiviral drugs. CONCLUSION: There have been no previous reports of MFS after Moderna COVID-19 vaccination. This case may provide new information about the possible neurological side effects of COVID-19 vaccines.

Anti-GQ1b Antibody Syndrome with Visual Impairment: A Retrospective Case Series.

BACKGROUND: Anti-GQ1b antibody syndrome referred to a clinical spectrum characterized by acute onset of ataxia, ophthalmoplegia and areflexia, while visual deterioration was rarely reported in terms of ocular disorders. This study aimed to describe the clinical characteristics of anti-GQ1b antibody syndrome with visual impairment. METHODS: The database at the First Affiliated Hospital of Sun Yat-sen University was searched from 2014 to 2020. Patients with anti-GQ1b IgG were identified and divided into two groups according to the existence of optic neuropathy. Clinical and laboratory data of these subjects between the two groups were collected and analyzed. All patients were followed up by telephone to assess the outcome. RESULTS: A total of 12 patients with seropositive anti-GQ1b antibody were included, 75% of which got antecedent infection. Of these cases, 3 showed visual deterioration accompanied by abnormal orbital magnetic resonance imaging or visual evoked potentials, and the other 9 didn't show any evidence of vision impairment. Patients in the optic neuropathy group presented prominent visual impairments as initial symptoms and were more likely to suffer from facial weakness. There were 4 patients in normal visual acuity group complaining of blurred vision due to intraocular muscle paralysis, which was distinguished by subsequent examination. The combination of glucocorticoids and intravenous immunoglobulin was applied to treat patients with optic neuropathy. CONCLUSIONS: This study provides strong evidence that anti-GQ1b antibody syndrome can exhibit visual impairment, which helps further expand the clinical spectrum of anti-GQ1b antibody syndrome. More attention should be paid to the physical and supplementary ophthalmological examination to explore the pathogenesis and treatment of anti-GQ1b antibody syndrome.

Graves' disease with anti-GQ1b antibody syndrome: a rare case report.

BACKGROUND: Graves' disease and anti-GQ1b antibody syndrome are both autoimmune diseases, and there have been few reports on whether there is a correlation between the two. In this study, we present the case of a woman who was diagnosed with Graves' disease and anti-GQ1b antibody syndrome in succession. CASE PRESENTATION: The chief complaints of this patient were limb weakness and blurred vision. Graves' disease was diagnosed by examination of thyroid function and thyroid autoantibodies, but the clinical symptoms were not relieved after antihyperthyroidism treatment. Finally, it was found that Graves' disease was complicated by anti-GQ1b antibody syndrome, and the symptoms were relieved after treatment with glucocorticoids and intravenous immunoglobulin. We also explored the possible mechanism of these diseases through a literature review. CONCLUSIONS: We report a rare case of the cooccurrence of Graves' disease and anti-GQ1b antibody syndrome. Immune dysregulation might be the pathogenesis of the association, but there is no precise supporting evidence, and more research is needed.

Mother and son cases of Bickerstaff's brainstem encephalitis and fisher syndrome with serum anti-GQ1b IgG antibodies: a case report.

BACKGROUND: Bickerstaff's brainstem encephalitis (BBE) and Fisher syndrome (FS) are immune-mediated diseases associated with anti-ganglioside antibodies, specifically the anti-GQ1b IgG antibody. These two diseases potentially lie on a continuous spectrum with Guillain-Barré Syndrome (GBS). There are some reports of family cases of GBS and fewer of FS. However, there are no reports of family cases of BBE and FS. CASE PRESENTATION: We report a familial case of an 18-year-old son who had BBE and his 52-year-old mother diagnosed with FS within 10 days. The son showed impaired consciousness 1 week after presenting with upper respiratory symptoms and was brought to our hospital by his mother. He showed decreased tendon reflexes, limb ataxia, albuminocytologic dissociation in his spinal fluid, and positive serum anti-GQ1b antibodies. Haemophilus influenzae was cultured from his sputum. He was diagnosed with BBE and treated with intravenous immunoglobulin (IVIg) therapy, which led to an improvement in symptoms. The mother presented with upper respiratory symptoms 3 days after her son was hospitalized. Seven days later, she was admitted to the hospital with diplopia due to limited abduction of the left eye. She showed mild ataxia and decreased tendon reflexes. Her blood was positive for anti-GQ1b antibodies. She was diagnosed with FS and treated with IVIg, which also led to symptomatic improvement. CONCLUSIONS: There are no previous reports of familial cases of BBE and FS; therefore, this valuable case may contribute to the elucidation of the relationship between genetic predisposition and the pathogenesis of BBE and FS.

A case of surgically-associated anti GQ1b antibody syndrome accompanied by saccadic ping pong gaze.

BACKGROUND: Periodic alternating ping-pong gaze (PPG) is a rare disease with few reports. To our knowledge, there was no report on anti GQ1b antibody syndrome accompanied by PPG. This paper reported a case of anti GQ1b antibody syndrome with Bickerstaff's Encephalitis (BBE) overlapping classic Guillain-Barre Syndrome (GBS) after aortic valve replacement, accompanied by an excessive PPG in the course of diagnosis and treatment, this was indeed rarely. CASE PRESENTATION: A 55-year-old male patient was admitted to our hospital with intermittent chest tightness for 3 months, and his condition has worsened in the past 10 days. Aortic valve replacement was performed because of the existence of the moderate and severe stenosis of aortic valve. Horizontal movement of the eyeball was involuntarily slow. The eyeball hovered and returned from one side to the other horizontally for 3-4 s per cycle. In combination with the patient's typical clinical and laboratory tests, the final diagnosis was anti GQ1b antibody syndrome BBE combined with GBS, accompanied by saccadic ping pong gaze. Intravenous immunoglobulin (0.4 g/kg) was given for immunomodulation, methylprednisolone (1000 mg) therapy and symptomatic treatment were performed in the patient. CONCLUSIONS: The patients were discharged from hospital on the thirtieth day because of economic reasons. After 6 months of follow up, the patients left behind a lack of fluency in speech and limb mobility, but the basic life can be taken care of by himself.

Atypical clinical manifestations of Miller Fisher syndrome.

Miller Fisher syndrome (MFS) is characterized by a clinical triad of ophthalmoplegia, ataxia, and areflexia, and is closely associated with serum anti-GQ1b antibody. Although the clinical triad is the cardinal diagnostic clue, a variety of other symptoms and signs beyond the triad have been reported. To elucidate the frequency and characteristics of atypical clinical manifestations of MFS, we recruited 38 patients with MFS and evaluated the symptoms or signs beyond the classic triad. Eleven (29%) of 38 patients had atypical clinical manifestations of MFS such as headache (n = 6), delayed facial palsy (n = 3), divergence insufficiency (n = 2), and taste impairment (n = 2). Headache was localized to the periorbital (n = 3), temporal (n = 2), or whole (n = 1) area. Only one of them showed bilateral papilledema and an elevated opening pressure in cerebrospinal fluid analysis. Delayed facial palsy developed after the other signs have reached nadir (n = 1) or started to improve (n = 2), and did not follow a pattern of descending paralysis with other cranial neuropathies. Two patients showed divergence insufficiency without external ophthalmoplegia, and another two had taste impairment over the entire tongue without the other signs of facial and glossopharyngeal nerve involvements. Our study shows that approximately 30% of MFS patients can have atypical clinical manifestations beyond the classic triad. These results reflect the broad clinical spectrum of MFS, and might be associated with the presence of additional antiganglioside antibodies besides anti-GQ1b in patients with MFS.

[Clinical analysis of 8 cases with anti-GQ1b antibody syndrome].

Objective: To investigate the clinical characterization, treatment and prognosis of anti-GQ1b antibody syndrome. Methods: The clinical data of 8 patients with positive serum anti-GQ1b antibody from the Department of Neurology of Nanjing Brain Hospital between June 2016 and July 2018 were analyzed retrospectively. Their serums were tested by immunoblotting. Relevant literatures were reviewed to investigate possible pathogenesis. Results: Of the 8 cases, 4 cases were male, 4 cases were female; their age ranged from 16 to 76 (47±21) years old. Seven of them were with acute onset, the time course of the disease ranged from 2 to 15 (7±4) days. Six cases had a history of influenza prior to the onset of the presenting symptoms. In terms of the clinical manifestations of the eight patients, two were affected with Guillain-Barre syndrome (GBS), two with Cavernous sinus syndrome, one with Miller Fisher syndrome, one with both GBS and spinal cord demyelination, one with Bulbar paralysis, and one with chronic inflammatory demyelinating polyneuropathy (CIDP). The anti-GQ1b antibody IgG in serum was positive in 6 patients, two of whom were combined with positive IgG of anti-GD1b antibody in serum. The anti-GQ1b antibody IgM in serum was positive in 1 patient, and the anti-GQ1b antibody IgM and anti-GT1b antibody IgM in cerebrospinal fluid (CSF) were both positive in the other patient. In terms of the treatment, 3 patients (3/8) received vitamin B treatment only, 2 patients (2/8) received steroid plus vitamin B treatment, 2 patients (2/8) received intravenous immunoglobulin (IVIG) plus vitamin B treatment, and 1 patient (1/8) received steroid plus IVIG treatment. During the 8-33 months' follow-up after discharge, 6 patients were significantly improved in their symptoms, one with mild diplopia, one with limbs weakness, numbness and difficulty in walking. The symptoms of one patient (case 3) fluctuated twice and recovered again after treatment. Conclusions: The disease spectrum of anti-GQ1b antibodies syndrome is broad, and main symptom is ophtalmoplegia. Immunotherapy with IVIG and steroid would be beneficial to prognosis.

Anti-ganglioside complex antibody profiles in a recurrent complicated case of GQ1b-seronegative miller fisher syndrome and Bickerstaff brainstem encephalitis: a case report.

BACKGROUND: Guillain-Barré syndrome (GBS), Miller Fisher syndrome (MFS) and Bickerstaff brainstem encephalitis (BBE) are a group of autoimmune neurological disorders (GBS spectrum disorder) that rarely recur. Recently, anti-ganglioside complex antibodies (GSC-Abs) were identified in patients with GBS spectrum disorder. However, there has been no case report describing GSC-Abs profiles in a recurrent case showing different phenotypes. CASE PRESENTATION: We report the case of a 33-year-old male patient with GQ1b-seronegative BBE-GBS after two prior episodes of MFS-GBS. Our patient showed ophthalmoplegia, ataxia, areflexia and a weakness of the extremities (MFS and GBS symptoms) in all episodes. In the episode reported here, our patient showed disturbed consciousness and an extensor response to cutaneous plantar stimulation was observed (BBE symptoms), with severe disability and requirement for artificial respiration management. GSC-Abs detected in previous episodes were also detected in the subsequent episodes, while new GSC-Abs emerged in each episode. Interestingly, whereas antibodies to GA1/GQ1b and GA1/GT1a, which are commonly identified in patients with GBS, MFS or BBE, appeared in all episodes, antibodies to GD1a/GD1b and GD1b/GT1b, which are predominantly associated with severe disability and the requirement for artificial respiration management in GBS, emerged for the first time in this episode. CONCLUSION: This study reports novel phenomena about the GSC-Abs profiles and its relationship with clinical features in a case with recurrent GBS spectrum disorder, showing different phenotypes in different episodes. Further studies are required to reveal the significance of the GSC-Abs profiles in recurrent GBS spectrum disorder.

Miller Fisher syndrome, Bickerstaff brainstem encephalitis and Guillain-Barré syndrome overlap with persistent non-demyelinating conduction blocks: a case report.

BACKGROUND: Miller Fisher syndrome (MFS) and Bickerstaff's Brainstem Encephalitis (BBE) share some clinical features and a common immunological profile characterized by anti-GQ1b antibodies. Some MFS patients overlap with Guillain-Barré syndrome (GBS) or BBE. We report a patient with MFS, BBE, and axonal GBS overlap in whom serial electrophysiological studies showed persistent motor conduction blocks (CBs). CASE PRESENTATION: A 61-year-old man acutely developed ophtalmoparesis, ataxia and areflexia suggesting MFS. Paresthesias, severe weakness, and drowsiness rapidly developed indicating an overlap with BBE and GBS. Preceding infection with Mycoplasma Pneumoniae and anti-GQ1b antibodies were detected. On day 4, nerve conduction study showed reduced or non-recordable compound muscle action potentials (CMAPs) and sensory nerve action potentials (SNAPs) without demyelinating features, indicating the electrodiagnosis of acute motor and sensory axonal neuropathy and suggesting a poor prognosis. Intravenous immunoglobulins (IVIg) were given but clinical status worsened to ophthalmoplegia, tetraplegia and coma needing mechanical ventilation. A second IVIg course was given and the patient was weaned off ventilation on day 41 and transferred to rehabilitation on day 57 with partial resolution of the ophthalmoplegia and limited recovery of muscle strength. Electrophysiology showed, after 10 weeks, greatly improved distal CMAP amplitudes suggesting the resolution of distal CBs while CBs in intermediate and proximal nerve segments emerged. CBs unusually persisted for four to 6 months without development of abnormal temporal dispersion. A third IVIg course was started on day 179 and the resolution of CBs mirrored the clinical improvement. CONCLUSIONS: GQ1b gangliosides are expressed in the nodal region of oculomotor nerves, muscle spindle afferents, peripheral nerves and possibly in the brainstem reticular formation. Anti-GQ1b antibodies may explain the complex symptomatology and the overlap between MFS, BBE, and GBS. CBs that persisted and recovered without the development of temporal dispersion suggest that weakness was due to a sustained, antibody-mediated, attack at the nodal region inducing a non-demyelinating conduction failure as expression of an acute onset, long lasting, nodopathy. Serial electrophysiological studies allowed not only to understand the underlying pathophysiology and formulate a more correct prognosis but also to guide the treatment.

Headache and Ophthalmoparesis: Case Report of an "Atypical" Incomplete Miller-Fisher Syndrome.

OBJECTIVE: To expand the differential diagnosis of headache and ophthalmoparesis by describing a case report in which anti-GQ1b was demonstrated to be the cause. BACKGROUND: Anti-GQ1b antibody syndrome refers to a clinical spectrum of conditions that share common mechanisms and overlapping manifestations, including the Miller-Fisher syndrome, pharyngeal-cervical-brachial weakness, and Bickerstaff brainstem encephalitis. Rare atypical cases presenting as acute ophthalmoparesis (AO) without ataxia or areflexia have been described. Headache is a rare condition in these disorders. METHODS: A 49-year-old woman with no history of headaches began experiencing an acute severe bilateral throbbing headache associated with nausea and photophobia. Five days later, she developed constant binocular horizontal diplopia. RESULTS: Bilateral paresis of both sixth nerves was noted. Her ocular fundi, tendon reflexes, and other findings of the physical exam were normal. In addition, both a brain MRI performed with gadolinium and a lumbar puncture yielded normal results. Serum anti-GQ1b IgG was found to be positive. Her symptoms resolved completely following treatment with immunoglobulins (0.4 g/kg/day for 5 days). CONCLUSIONS: This is the first reported case of AO related to anti-GQ1b antibodies presenting with headache as its initial symptom. The presence of anti-GQ1b antibodies should be determined in patients with headache and AO of unknown origin. Immunoglobulins could hasten the resolution of symptoms in these patients.

Ganglioside GQ1b induces dopamine release through the activation of Pyk2.

Growing evidence indicates that GQ1b, one of the gangliosides members, contributes to synaptic transmission and synapse formation. Previous studies have shown that GQ1b could enhance depolarization induced neurotransmitter release, while the role of GQ1b in asynchronous release is still largely unknown. Here in our result, we found low concentration of GQ1b, but not GT1b or GD1b (which were generated from GQ1b by plasma membrane-associated sialidases), evoked asynchronous dopamine (DA) release from both clonal rat pheochromocytoma PC12 cells and rat striatal slices significantly. The release peaked at 2 min after GQ1b exposure, and lasted for more than 6 min. This effect was caused by the enhancement of intracellular Ca(2+) and the activation of Pyk2. Inhibition of Pyk2 by PF-431396 (a dual inhibitor of Pyk2 and FAK) or Pyk2 siRNA abolished DA release induced by GQ1b. Moreover, Pyk2 Y402, but not other tyrosine site, was phosphorylated at the peaking time. The mutant of Pyk2 Y402 (Pyk2-Y402F) was built to confirm the essential role of Y402 activation. Further studies revealed that activated Pyk2 stimulated ERK1/2 and p-38, while only the ERK1/2 activation was indispensable for GQ1b induced DA release, which interacted with Synapsin I directly and led to its phosphorylation, then depolymerization of F-actin, thus contributed to DA release. In conclusion, low concentration of GQ1b is able to enhance asynchronous DA release through Pyk2/ERK/Synapsin I/actin pathway. Our findings provide new insights into the role of GQ1b in neuronal communication, and implicate the potential application of GQ1b in neurological disorders.

Listeria meningoencephalitis and anti-GQ1b antibody syndrome.

We report the first case of Listeria monocytogenes meningoencephalitis associated with anti-GQ1b antibody syndrome in an immunocompetent adult. A prompt diagnosis, made thanks to the multidisciplinary contribution, allowed a combined therapeutic approach leading to final favourable outcome, despite several intercurrent complications.

CD134 is a cellular receptor specific for human herpesvirus-6B entry.

Human herpesvirus-6B (HHV-6B) is a T lymphotropic ß-herpesvirus that is clearly distinct from human herpesvirus-6A (HHV-6A) according to molecular biological features. The International Committee on Taxonomy of Viruses recently classified HHV-6B as a separate species. The primary HHV-6B infection causes exanthem subitum and is sometimes associated with severe encephalopathy. More than 90% of the general population is infected with HHV-6B during childhood, and the virus remains throughout life as a latent infection. HHV-6B reactivation causes encephalitis in immunosuppressed patients. The cellular receptor for HHV-6A entry was identified as human CD46, but the receptor for HHV-6B has not been clear. Here we found that CD134, a member of the TNF receptor superfamily, functions as a specific entry receptor for HHV-6B. A T-cell line that is normally nonpermissive for HHV-6B infection became highly susceptible to infection when CD134 was overexpressed. CD134 was down-regulated in HHV-6B-infected T cells. Soluble CD134 interacted with the HHV-6B glycoprotein complex that serves as a viral ligand for cellular receptor, which inhibited HHV-6B but not HHV-6A infection in target cells. The identification of CD134 as an HHV-6B specific entry receptor provides important insight into understanding HHV-6B entry and its pathogenesis.

Progressive subacute Miller-Fisher syndrome successfully treated with plasmapheresis.

BACKGROUND: Miller-Fisher Syndrome (MFS) is a rare acute polyneuropathy composed of the clinical triad of ataxia, areflexia and ophthalmoplegia, with a monophasic, self-limited course and spontaneous improvement. CASE REPORT: The authors present a 65-year-old man with Miller-Fisher syndrome consisting of bilateral ophthalmoplegia, trigeminal and facial nerve palsy, mild ataxia and peripheral neuropathy. The disease had a progressive, subacute course within 3 months. A high titer of anti-GQ1b antibodies was detected. As a result of plasmapheresis, complete recovery was achieved. CONCLUSIONS: The presented case was atypical in its clinical course and treatment. It could support the theory of the continuity between MFS, Bickerstaff brainstem encephalitis (BBE), and Guillain-Barré syndrome (GBS).