Equine Multinodular Pulmonary Fibrosis in association with asinine herpesvirus type 5 and equine herpesvirus type 5: a case report

A standardbred gelding with a history of 10 days pyrexia and lethargy was referred to the Equine Hospital at the Swedish University of Agricultural Sciences in Uppsala, Sweden. The horse had tachypnea with increased respiratory effort and was in thin body condition. Laboratory findings included leukocytosis, hyperfibrinogenemia and hypoxemia. Thoracic radiographs showed signs of pneumonia with a multifocal nodular pattern, which in combination with lung biopsy findings indicated Equine Multinodular Pulmonary Fibrosis (EMPF). EMPF is a recently described disease in adult horses with clinical signs of fever, weight loss and respiratory problems. The pathological findings include loss of functional pulmonary parenchyma due to extensive nodular interstitial fibrosis which has been related to infection with the equine herpesvirus type 5 (EHV-5). In this case, lung biopsy and tracheal wash samples tested positive for both asinine herpesvirus type 5 (AHV-5) and EHV-5 using PCR assays. The horse failed to respond to treatment and was euthanized for humane reasons. Postmortem examination confirmed the diagnosis of EMPF. This case suggests that not only EHV-5 alone should be considered in association with the development of this disease

TECPR2 Associated Neuroaxonal Dystrophy in Spanish Water Dogs.

Clinical, pathological and genetic examination revealed an as yet uncharacterized juvenile-onset neuroaxonal dystrophy (NAD) in Spanish water dogs. Affected dogs presented with various neurological deficits including gait abnormalities and behavioral deficits. Histopathology demonstrated spheroid formation accentuated in the grey matter of the cerebral hemispheres, the cerebellum, the brain stem and in the sensory pathways of the spinal cord. Iron accumulation was absent. Ultrastructurally spheroids contained predominantly closely packed vesicles with a double-layered membrane, which were characterized as autophagosomes using immunohistochemistry. The family history of the four affected dogs suggested an autosomal recessive inheritance. SNP genotyping showed a single genomic region of extended homozygosity of 4.5 Mb in the four cases on CFA 8. Linkage analysis revealed a maximal parametric LOD score of 2.5 at this region. By whole genome re-sequencing of one affected dog, a perfectly associated, single, non-synonymous coding variant in the canine tectonin beta-propeller repeat-containing protein 2 (TECPR2) gene affecting a highly conserved region was detected (c.4009C>T or p.R1337W). This canine NAD form displays etiologic parallels to an inherited TECPR2 associated type of human hereditary spastic paraparesis (HSP). In contrast to the canine NAD, the spinal cord lesions in most types of human HSP involve the sensory and the motor pathways. Furthermore, the canine NAD form reveals similarities to cases of human NAD defined by widespread spheroid formation without iron accumulation in the basal ganglia. Thus TECPR2 should also be considered as candidate gene for human NAD. Immunohistochemistry and the ultrastructural findings further support the assumption, that TECPR2 regulates autophagosome accumulation in the autophagic pathways. Consequently, this report provides the first genetic characterization of juvenile canine NAD, describes the histopathological features associated with the TECPR2 mutation and provides evidence to emphasize the association between failure of autophagy and neurodegeneration

TECPR2 domain structure and p.R1337W mutation associated with NAD in Spanish water dogs.

<p>(<b>A</b>) TECPR2 possesses three N-terminal WD (tryptophan-aspartic-acid dipeptide) repeats (red), a polylysine tract (green), and six C-terminal tectonin beta-propeller repeat (TECPR) domains (blue). (<b>B</b>) The arginine at position 1337 that is substituted by a tryptophan residue (red) is located in the sixth TECPR domain. Note that the mutation affects a conserved amino acid residue in all known TECPR2 orthologs. Highly conserved residues are marked in green.</p

Pedigree of the collected Spanish water dogs with NAD.

<p>Note the inbreeding loops and the likely common ancestors appearing 8 to 9 generations ago. Only for the numbered animals DNA was available. Affected animals are shown with black symbols; genotyped carriers of the causative mutation are indicated with half-filled symbols; females are shown as circles and males as squares.</p

Distribution of cervical and thoracic spinal cord spheroids in Spanish water dogs with NAD compared to mostly affected areas in human hereditary spastic paraparesis (HSP).

<p>In NAD affected Spanish water dogs (left), spheroids and neuronal loss were restricted to the sensory, ascending pathways localized to the grey matter of the spinal cord dorsal horn and single large spheroids were detected within the cuneate and gracile fasciculus. This might explain the clinical signs as gait disturbances, proprioceptive deficits, decreased spinal reflexes and urinary incontinence. In other human forms of NAD, HSP and <i>Pla2g6</i> knock-out mice (right), spinal cord spheroid formation is accentuated in the sensory pathways including the gracile fasciculus as well as the corticospinal tracts. Furthermore, also the descending motor pathways including the ventral horns as well as the descending pyramidal tracts are affected. Note that spinal cord histology of TECPR2 associated HSP in humans is unknown. Ascending, sensory pathways (red; transmission of sensory signals from the periphery (red arrow) via dorsal horn (DH) towards the brain): Dorsal funiculus composing of gracile fasciculus (GF) and cuneate fasciculus (CF); Spinocerebellar tracts with: dorsal spinocerebellar tract (DST) and ventral spinocerebellar tract (VST); Descending, motor pathways (blue; signal transmission via the ventral horn (VH) neurons towards the muscles; blue arrow): Pyramidal tracts with lateral corticospinal tract (LCT) and ventral corticospinal tract (VCT).</p

Association of the <i>TECPR2</i> missense mutation with the NAD phenotype in Spanish water dogs.

<p>Association of the <i>TECPR2</i> missense mutation with the NAD phenotype in Spanish water dogs.</p

Histology of NAD in Spanish water dogs.

<p>(<b>A</b>, <b>B</b>) Histology of the brain stem (cuneate nucleus) stained with hematoxylin and eosin revealed numerous large granular axonal swellings (spheroids; arrow). Note the hypereosinophilic central target-like core structure of distinct spheroids (<b>A</b>). Single neurons displayed an accumulation of a finely or coarse granular, intensely eosinophilic material associated with the soma (arrow) displacing the Nissl substance. A high proportion of neurons adjacent to affected areas displayed a normal morphology with equally distributed Nissl substance (arrowhead, <b>B</b>).</p