Properties of Aleutian disease virus assayed with feline kidney cells

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Abstract
Summary Properties of Aleutian disease virus (ADV) were studied using feline kidney cells, line CRFK, to assay virus by the induction of nuclear antigen. ADV nuclear antigen was detected by immunofluorescent staining. Titers of virus obtained from mink spleens at 10–8 days after infection were usually between 103 and 105 infectious units per gram of spleen. ADV was purified by fluorocarbon extraction, differential centrifugation, biogel A-15 chromatography and CsCl equilibrium centrifugation. The molecular weight of the virus was estimated to be 3–5 × 106 daltons. The density of antigen-inducing virus in equilibrium CsCl gradients was 1.32–1.34 g/cm3. On velocity sucrose gradients, antigen-inducing virus had a sedimentation coefficient of approximately 110S. The virus was not neutralized by sera from chronically infected mink and ferrets and by sera from experimentally infected mink. ADV was resistant to ionic and nonionic detergents and lipid solvents. The titer of partially purified virus was reduced as much as 700-fold by proteolytic enzymes but not by DNase or RNase. The virus was inactivated slowly at 56° C; the initial half-life was 90 minutes. It is concluded that the properties of ADV can be determined by assay in CRFK cells, thus facilitating virological study of the disease.