Neuropathologic features of Aleutian disease in farmed mink in Ireland and molecular characterization of Aleutian mink disease virus detected in brain tissues.

A neuropathologic survey was conducted on mink brains from the 5 licensed mink farms in Ireland. The survey was part of a transmissible spongiform encephalopathy surveillance study. Aleutian disease (AD) was present on 4 of the 5 farms (80%). Neuropathologic features of nonsuppurative meningoencephalitis were common in mink from the 4 affected farms but were absent in the mink from the fifth farm, which was free of AD. The meningoencephalitis was characterized by infiltrates of lymphocytes and plasma cells, which were present in meninges, perivascular spaces, and the brain parenchyma. Fibrinoid necrotizing arteritis was seen in 11 mink brains, all of which were obtained from a single farm. Aleutian mink disease virus (AMDV) sequences for the capsid protein VP2 were obtained from brain samples from all affected farms. Although containing previously unreported amino acid residues, similarities with European and North American isolates were observed in the hypervariable regions within VP2, suggesting Irish AMDV is related to those isolates. The predicted amino acid residues, suspected of conferring pathogenicity at certain positions of the VP2 sequence, were present in the viral nucleic acid sequences.