Benavides J, Fuertes M, García-Pariente C, Ferreras M C, García Marín J F, Pérez V
Departamento de Patología Animal: Medicina Animal, Anatomía Patológica, Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
J Comp Pathol. 2006 Feb-Apr;134(2-3):219-30. doi: 10.1016/j.jcpa.2005.11.003.
Of 118 sheep with visna, 12 showed myelitis as the only nervous lesion. They were ovine lentivirus (OvLV)-seropositive and provirus DNA was demonstrated by LTR-PCR in all the samples with lesions. Clinically, all showed hindlimb paralysis and some were completely recumbent. Grossly, a swollen and discoloured area was identified in the white matter in 10 sheep. Microscopical changes consisted of a wedge-shaped area of non-suppurative leucomyelitis with mononuclear perivascular cuffing, demyelination and white matter degeneration. Except for two samples, grey matter was affected adjacent to severe white matter lesions. Three different microscopical patterns of lesion were identified, all having in common the presence of perivascular inflammation: the so-called vascular pattern was characterized by perivascular cuffs with minimal lesions in the adjacent neuroparenchyma; the malacic pattern, which was the commonest type, was characterized by severe white matter destruction and small numbers of macrophages; and the infiltrative pattern was characterized by a severe infiltrate of histiocytes in the parenchyma. Maedi-visna virus antigen was detected immunohistochemically only in areas with lesions, and the degree of immunolabelling was unrelated to the severity of the damage. Diagnosticians should bear in mind that a considerable number of visna cases show only spinal cord lesions. Examination of paraffin wax-embedded samples by LTR-PCR and immunohistochemistry would seem useful in confirming a histopathological diagnosis of visna from spinal cord samples.
在118只患有维斯纳病的绵羊中，12只表现为脊髓炎是唯一的神经病变。它们为绵羊慢病毒（OvLV）血清阳性，并且通过LTR-PCR在所有有病变的样本中均检测到前病毒DNA。临床上，所有羊均表现为后肢麻痹，有些完全卧地不起。大体检查时，在10只羊的白质中发现了一个肿胀且变色的区域。显微镜下变化包括一个楔形的非化脓性白质脊髓炎区域，伴有单核细胞血管周围套袖状浸润、脱髓鞘和白质变性。除两个样本外，严重白质病变附近的灰质也受到影响。识别出三种不同的显微镜下病变模式，它们的共同特征是存在血管周围炎症：所谓的血管模式的特征是血管周围套袖状浸润，相邻神经实质的病变最小；软化模式是最常见的类型，其特征是严重的白质破坏和少量巨噬细胞；浸润模式的特征是实质中有严重的组织细胞浸润。仅在有病变的区域通过免疫组织化学检测到梅迪-维斯纳病毒抗原，免疫标记程度与损伤严重程度无关。诊断人员应牢记，相当数量的维斯纳病病例仅表现为脊髓病变。通过LTR-PCR和免疫组织化学检查石蜡包埋样本似乎有助于从脊髓样本中确诊维斯纳病的组织病理学诊断。
