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Purification of a Mild Mottle Strain of Peanut Mottle Virus. O. R. Paguio, Former Graduate Assistant, Department of Plant Pathology and Plant Genetics, University of Georgia, Athens 30601; C. W. Kuhn, Professor, Department of Plant Pathology and Plant Genetics, University of Georgia, Athens 30601. Phytopathology 63:720-724. Accepted for publication 19 December 1972. DOI: 10.1094/Phyto-63-720.

Infectivity assays and electron microscopic examinations of various steps of purification indicated that particles of a mild mottle strain of peanut mottle virus severely aggregated when concentrated by differential ultracentrifugation and polyethylene glycol precipitation. Aggregation was partially overcome, however, when polyethylene glycol precipitated virus particles were resuspended in phosphate buffer containing 0.001 M Cleland’s reagent (dithiothreitol). This procedure allowed the formation of a single opalescent zone in density-gradient columns. The absorption spectrum of the purified virus was typical for nucleoproteins, with minimum and maximum absorbance at 246 and 260 nm, respectively. The most frequent length in the modal distribution of the particles was about 725 nm. Antiserum from an immunized rabbit had a specific titer of 1:256 and 1:128 with ring interface and microprecipitin tests, respectively.