Isolation, purification and structure of Aleutian disease virus by immunological techniques

Vaccination with Aleutian mink disease parvovirus (AMDV) capsid proteins enhances disease, while vaccination with the major non-structural AMDV protein causes partial protection from disease

Vaccination studies were performed with partially purified recombinant AMDV VP1/2 capsids as well as with the major AMDV non-structural protein (NS1). All vaccine constructs induced an antibody response, but did not prevent infection upon challenge with AMDV. The severity of Aleutian disease (AD) was judged by the serum gammaglobulin level, the quantity of peripheral blood CD8 lymphocytes, antibody titers to VP1/2 and NS1 proteins and mink death rates. The VP1/2 vaccine constructs enhanced the disease process with drastic death rates for the vaccinated mink. On the contrary, the NS1 vaccine constructs resulted in milder AD than seen in the non-vaccinated mink.

Mink with Aleutian disease have high-affinity antiviral antibodies

Mink persistently infected with Aleutian disease virus (ADV) develop plasmacytosis (hypergammaglobulinaemia) and immune complex disease. Mink of different colour phases were infected with different strains of ADV and bled at different times after infection. The average antibody affinities (Kav) were measured in the sera and found to fall in the range of 2 X 10(9) - 2 X 10(10) M-1, thus indicating good-quality antibodies. In sera of non-Aleutian genotype mink a decline in Kav during development of plasmacytosis was observed. Moreover, the antibody heterogeneity (alpha values) tended to decrease during the disease progress. In contrast, the Kav values in sera of infected Aleutian genotype mink remained relatively high after hypergammaglobulinaemia developed, and the antibody heterogeneity for certain of the mink sera indicated restricted heterogeneity (high alpha values). In agreement with the clonal selection theory, low virus burden (for instance, during infection with a low-virulence ADV strain) generated relatively higher affinity antibodies than a high virus burden for instance, the highly virulent Utah I strain of ADV). Furthermore, antibodies present in low concentration were of higher affinity than antibodies present in high concentrations. The relatively high affinity antibodies found in this study indicate that if the immune complex disease seen in AD is caused by virus-anti-virus antibodies, good-quality antibodies are likely to be responsible for the pathological findings.

Serological analyses of different mink Aleutian disease virus strains

Four different isolates of Aleutian disease virus have been compared electrophoretically and serologically. These were the DK and Utah 1 isolates, known as highly virulent strains, the Pullman isolate, known as a low virulent strain and the avirulent ADV-G isolate, which is the only strain grown in cell culture. ADV-G was shown to migrate in agarose electrophoresis 22 per cent slower than the other strains. Several murine monoclonal antibodies were prepared against each of the isolates. Each one reacted with all 4 of the isolates, but a few showed higher affinity for some of the isolates. Competitive RIA analyses were also performed, and these studies indicated some serological differences between the 4 strains. It is concluded that ADV-G polypeptides are chemically different but immunologically cross-reacting with the polypeptides present on the field ADV strains. It is suggested that the small serological differences seen between the field strains might be caused by slightly different in vivo proteolytic degradation of the viral capsid proteins and thus might not be taken as an indication of strain variation.

Inhibition of precipitation in counter current electrophoresis. A sensitive method for detection of mink antibodies to Aleutian disease virus

Inhibition of precipitation in counter current electrophoresis was at least 32 more sensitive when compared to the normal counter current electrophoresis for the demonstration of mink antibodies against Aleutian disease virus (ADV). ADV antigen can be produced from mink organs or in cell culture. The reactivity of the two types of antigen in the two kinds of counter current electrophoresis methods is described in this report. When 22 mink sera were titrated in normal counter current electrophoresis against cell culture produced antigen and organ produced antigen, significantly lower antibody titres were found with cell culture produced antigen. The difference was not found when inhibition of precipitation of counter current electrophoresis was used.

[Pathogenesis of aleutian mink disease. VII. Chronic hepatitis with bile duct proliferation]

Aleutian disease is a chronic persistent viral infection of mink characterized by hypergammaglobulinema, generalized plasmacytosis, sclerosing glomerulonephritis, polyarteritis, and plasma cell hepatitis with bile duct proliferation. The development of hepatic lesions was studied both light- and electron-microscopically in mink experimentally infected with Aleutian disease virus. Fifteen normal and 99 mink experimentally infected with Aleutian disease virus were used. Experimental mink were killed in intervals from 3 weeks to 23 months after infection, and liver sections were processed for both light- and electron-microscopic studies. Experimentally infected mink developed portal and intralobular lymphocytic and plasmacytic infiltrates in the liver 3 weeks after infection. Four to five weeks after infection there was evidence of early bile duct proliferation that began as an outgrowth of the portal bile ducts. Three to five months after infection a marked bile duct proliferation was present in some of the portal triads and adjacent liver lobules; but there was no tendency of these lesions to progress into biliary cirrhosis. Ultrastructural characteristics of proliferating bile duct cells were marked deformation, formation of multiple cell layers, reduction in the number of microvilli and desmosomes, and infiltration of the epithelial cells by lymphoid cells and plasmacytes. The hepatic lesions either develop by direct virus stimulation or by the deposition of virus-antibody complexes.