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.