Neurotoxic potential of reactive astrocytes in canine distemper demyelinating leukoencephalitis.

Canine distemper virus (CDV) causes a fatal demyelinating leukoencephalitis in young dogs resembling human multiple sclerosis. Astrocytes are the main cellular target of CDV and undergo reactive changes already in pre-demyelinating brain lesions. Based on their broad range of beneficial and detrimental effects in the injured brain reactive astrogliosis is in need of intensive investigation. The aim of the study was to characterize astrocyte plasticity during the course of CDV-induced demyelinating leukoencephalitis by the aid of immunohistochemistry, immunofluorescence and gene expression analysis. Immunohistochemistry revealed the presence of reactive glial fibrillary acidic protein (GFAP)+ astrocytes with increased survivin and reduced aquaporin 4, and glutamine synthetase protein levels, indicating disturbed blood brain barrier function, glutamate homeostasis and astrocyte maladaptation, respectively. Gene expression analysis revealed 81 differentially expressed astrocyte-related genes with a dominance of genes associated with neurotoxic A1-polarized astrocytes. Accordingly, acyl-coA synthetase long-chain family member 5+/GFAP+, and serglycin+/GFAP+ cells, characteristic of A1-astrocytes, were found in demyelinating lesions by immunofluorescence. In addition, gene expression revealed a dysregulation of astrocytic function including disturbed glutamate homeostasis and altered immune function. Observed findings indicate an astrocyte polarization towards a neurotoxic phenotype likely contributing to lesion initiation and progression in canine distemper leukoencephalitis.

Post-vaccinal distemper encephalitis in two Border Collie cross littermates.

CASE HISTORY: One 4.5-month-old male Border Collie cross presented with aggression and seizures in October 2006. A 16-month-old, female, spayed Border Collie cross presented with hypersalivation and a dropped jaw and rapidly became stuporous in September 2007. The dogs were littermates and developed acute neurological signs 5 and 27 days, respectively, after vaccination with different modified live vaccines containing canine distemper virus. HISTOPATHOLOGICAL FINDINGS: Sections of brain in both dogs showed evidence of encephalitis mainly centred on the grey matter of brainstem nuclei, where there was extensive and intense parenchymal and perivascular infiltration of histiocytes and lymphocytes. Intra-nuclear and intra-cytoplasmic inclusions typical of distemper were plentiful and there was abundant labelling for canine distemper virus using immunohistochemistry. DIAGNOSIS: Post-vaccinal canine distemper. CLINCIAL RELEVANCE: Post-vaccinal canine distemper has mainly been attributed to virulent vaccine virus, but it may also occur in dogs whose immunologic nature makes them susceptible to disease induced by a modified-live vaccine virus that is safe and protective for most dogs.

Encephalomyelitis associated with microsporidian infection in farmed greater amberjack, Seriola dumerili (Risso).

An outbreak of a disease characterized by a peculiar spiral movement in farmed greater amberjack, Seriola dumerili (Risso), occurred in Kagoshima Prefecture, Japan, in May 2008, immediately after importing the fish from China. Although neither bacteria nor viruses were detected in routine diagnostic tests, histopathological observations of the affected fish revealed severe inflammation in the tegmentum of the brain including the medulla oblongata and the anterior part of the spinal cord. In addition, a microsporidian parasite was observed in the nerve cell bodies or axons in the inflamed tissues. We identified a microsporidian small subunit rRNA gene (SSU rDNA) from the lesion, and the sequence showed 96.1% identity with that of Spraguea lophii. Subsequent in situ hybridization using probes presumably specific to the SSU rRNA confirmed that the parasite observed in histopathology harboured the identified SSU rRNA. Apparently degenerated microsporidian cells or spores were also frequently observed in tissue sections. Thus, the disease was most probably caused by the infection of a hitherto unknown microsporidian parasite that has a genetic affinity to the genus Spraguea, in the central nervous system of the amberjack.

Eastern equine encephalomyelitis virus infection in a horse from California.

A yearling quarter horse, which was raised in southern California, received routine vaccinations for prevention of infection by Eastern equine encephalomyelitis virus (EEEV). One week later, severe neurologic signs developed, and the horse was humanely destroyed. A vaccine-related encephalomyelitis was later suspected. A final diagnosis of EEEV infection was established on the basis of acute onset of the neurologic signs, histopathologic and serologic testing, and isolation and molecular characterization of EEEV from brain tissue. The vaccine was extensively tested for viral inactivation. Nucleotide sequences from the vaccine and the virus isolated in the affected horse were also compared. In California, arboviral encephalomyelitides are rarely reported, and EEEV infection has not previously been documented. This report describes the occurrence of EEEV infection in the horse and the investigation to determine the source of infection, which was not definitively identified.

Disseminated granulomatous meningoencephalomyelitis in a dog.

A 6-year-old, intact, female miniature Doberman pinscher was evaluated for lethargy, intermittent back pain, and unstable gait. Physical and neurological findings included bradycardia, hypothermia, hyperesthesia, progressive and ascending ataxia, and proprioceptive deficits in all limbs. Laboratory findings and magnetic resonance imaging were consistent with disseminated granulomatous meningoencephalomyelitis, confirmed later by microscopy.

[A case of acute disseminated Mucor encephalitis in a heifer]. / Ein Fall von akuter disseminierter Mucor-Enzephalitis bei einem Rind.

The case of a 2 1/2 year old Swiss Braunvieh heifer suffering from an acute disseminated mycotic encephalitis caused by a Mucorales spp. infection is presented. Clinical signs and analysis of cerebrospinal fluid (increased protein concentration and pleocytosis) were typical for an acute encephalitis, probably due to a listeriosis. The histological examination of the brain revealed an acute disseminated thrombo-embolic encephalomyelitis due to a fungi infection, morphologically consistent with Mucorales spp. The occurrence of bovine cerebral mucormycosis is rare and therefore the veterinarian should become aware of a case which was clinically not distinguishable from a listeriosis.

Distemper encephalitis in pups after vaccination of the dam.

A five-year-old labrador bitch which had whelped 10 pups three days previously was given booster vaccination against distemper, adenovirus, parvovirus, parainfluenzavirus and leptospirosis. Eighteen days later, signs of central nervous system disease developed in some of the pups, five of which were ultimately euthanased. The cause of the nervous disease was found to be canine distemper, and serological studies showed that the infection was limited to some members of the litter, suggesting that the vaccinal rather than a field virus was more likely to have been responsible.

Encephalitis in dogs associated with a batch of canine distemper (Rockborn) vaccine.

During a period of seven months in 1982-83 cases of postvaccinal encephalitis were recorded in dogs in various parts of Britain after the administration of a particular batch of combined distemper/hepatitis vaccine. Detailed investigations of one of these cases revealed that the distemper component was responsible and the vaccine virus was recovered from the brain of an affected dog.