VIEW ARTICLE

Antiserum Preparation and Partial Purification of Potato Virus A. Cesar E. Fribourg, Research Assistant, Department of Plant Pathology, University of Wisconsin, Madison 53706; G. A. de Zoeten, Assistant Professor, Department of Plant Pathology, University of Wisconsin, Madison 53706. Phytopathology 60:1415-1421. Accepted for publication 4 April 1970. DOI: 10.1094/Phyto-60-1415.

Potato virus A (PVA) was partially purified employing three different buffer systems (borate, citrate, and phosphate). During initial extraction, 0.01 m 2-mercaptoethanol plus 0.01 m ascorbic acid in 0.05 m phosphate buffer pH 7 followed by dialysis against the same buffer stabilized the virus. Aluminum oxide added before the grinding of the tissues also gave a high degree of stabilization. These results show that an oxidative degradation of PVA may be at work during the first steps in purification. Carbon tetrachloride was used for clarification in a 1:1 sap solvent ratio. Infectivity of the preparations was best maintained when borate buffer was used for resuspension. Density-gradient centrifugation in a borate buffer system did not produce infectious fractions in the sucrose gradients, but gave infectious pellets of PVA at the bottom of the gradient tubes. Electron microscopy showed that degradation and loss of protein from the virus particles may account for the loss of PVA infectivity. An antiserum against PVA was produced with a homologous titer of 1/5₁₂ and a heterologous titer against a PVY isolate of 1/6₄.