A theory of virus-induced demyelination in the Landry-Guillain-Barré syndrome

Acute paretic syndrome in juvenile White Leghorn chickens resembles late stages of acute inflammatory demyelinating polyneuropathies in humans

Background

Sudden limb paresis is a common problem in White Leghorn flocks, affecting about 1% of the chicken population before achievement of sexual maturity. Previously, a similar clinical syndrome has been reported as being caused by inflammatory demyelination of peripheral nerve fibres. Here, we investigated in detail the immunopathology of this paretic syndrome and its possible resemblance to human neuropathies.

Methods

Neurologically affected chickens and control animals from one single flock underwent clinical and neuropathological examination. Peripheral nervous system (PNS) alterations were characterised using standard morphological techniques, including nerve fibre teasing and transmission electron microscopy. Infiltrating cells were phenotyped immunohistologically and quantified by flow cytometry. The cytokine expression pattern was assessed by quantitative real-time PCR (qRT-PCR). These investigations were accomplished by MHC genotyping and a PCR screen for Marek's disease virus (MDV).

Results

Spontaneous paresis of White Leghorns is caused by cell-mediated, inflammatory demyelination affecting multiple cranial and spinal nerves and nerve roots with a proximodistal tapering. Clinical manifestation coincides with the employment of humoral immune mechanisms, enrolling plasma cell recruitment, deposition of myelin-bound IgG and antibody-dependent macrophageal myelin-stripping. Disease development was significantly linked to a 539 bp microsatellite in MHC locus LEI0258. An aetiological role for MDV was excluded.

Conclusions

The paretic phase of avian inflammatory demyelinating polyradiculoneuritis immunobiologically resembles the late-acute disease stages of human acute inflammatory demyelinating polyneuropathy, and is characterised by a Th1-to-Th2 shift.

Vaccination and autoimmunity-'vaccinosis': a dangerous liaison?

The question of a connection between vaccination and autoimmune illness (or phenomena) is surrounded by controversy. A heated debate is going on regarding the causality between vaccines, such as measles and anti-hepatitis B virus (HBV), and multiple sclerosis (MS). Brain antibodies as well as clinical symptoms have been found in patients vaccinated against those diseases. Other autoimmune illnesses have been associated with vaccinations. Tetanus toxoid, influenza vaccines, polio vaccine, and others, have been related to phenomena ranging from autoantibodies production to full-blown illness (such as rheumatoid arthritis (RA)). Conflicting data exists regarding also the connection between autism and vaccination with measles vaccine. So far only one controlled study of an experimental animal model has been published, in which the possible causal relation between vaccines and autoimmune findings has been examined: in healthy puppies immunized with a variety of commonly given vaccines, a variety of autoantibodies have been documented but no frank autoimmune illness was recorded. The findings could also represent a polyclonal activation (adjuvant reaction). The mechanism (or mechanisms) of autoimmune reactions following immunization has not yet been elucidated. One of the possibilities is molecular mimicry; when a structural similarity exists between some viral antigen (or other component of the vaccine) and a self-antigen. This similarity may be the trigger to the autoimmune reaction. Other possible mechanisms are discussed. Even though the data regarding the relation between vaccination and autoimmune disease is conflicting, it seems that some autoimmune phenomena are clearly related to immunization (e.g. Guillain-Barre syndrome). The issue of the risk of vaccination remains a philosophical one, since to date the advantages of this policy have not been refuted, while the risk for autoimmune disease has not been irrevocably proved. We discuss the pros and cons of this issue (although the temporal relationship (i.e. always 2-3 months following immunization) is impressive).

Myelin- and microbe-specific antibodies in Guillain-Barré syndrome

We surveyed the frequency of reported infections and target autoantigens in 56 Guillain Barré syndrome (GBS) patients by detecting antibodies to myelin and microbes. Sulfatide (43%), cardiolipin (48%), GD1a (15%), SGPG (11%), and GM3 (11%) antibodies were the most frequently detected heterogenous autoantibodies. A wide spectrum of antimicrobial IgG and IgM antibodies were also detected; mumps-specific IgG (66%), adenovirus-specific IgG (52%), varicella-zoster virus-specific IgG (46%), and S. pneumoniae serotype 7-specific IgG (45%) were the most prevalent. Our results indicate that polyclonal expansion of physiologic and pathologic antibodies and/or molecular mimicry likely occurs following infection and is related to other autoimmune factors in the etiology of GBS. Although no single definitive myelin-specific autoantibody was identified, our results suggest a unique pattern of reactivity against autoantigens.

Aetiological role of viruses in multiple sclerosis: a review

Introduction

Vestibular neuronitis--serum and CSF virus antibody titer

The cerebrospinal fluid (CSF) findings of patients with vestibular neuronitis were virologically evaluated and discussed in contrast to those of herpes zoster. CSF samples obtained from seven patients with vestibular neuronitis, aged 28 to 55 years, were examined. The results were as follows: The CSF protein level in the vestibular neuronitis showed the peculiar change; i.e. its level was normal at the onset period of vertigo, but it rose to abnormal levels mostly in the period of two weeks, while the cell count remained normal throughout all phases of our study. Herpes simplex virus (HSV) type 1 IgG antibody titers measured by indirect immunofluorescent antibody technique (IF) in paired sera rose in one of the seven cases of vestibular neuronitis, but the antibody titers of the same virus in the CSF were not detected. HSV type 1 IgG antibody titers measured by IF in the CSF were detected in two of seven cases of vestibular neuronitis, but not significant. The ratio of EB virus (EBV) capsid antigen IgG antibody titers in CSF to that in serum ranged from 1:160 to 1:80 in vestibular neuronitis. There was no direct available evidence that vestibular neuronitis caused a break in blood-CSF barrier, an increase in IgG synthesis in the central nervous system or active infection with HSV, varicella zoster virus (VZV), or EBV. In this paper, we summarized the recent information on studies of the CSF and a latent herpes virus infection in order to give perspective to the pathogenesis of vestibular neuronitis.