Purificação e estudo de algumas propriedades do vírus da necrose branca do fumo

This work presents the results of the purification of the Brazilian tobacco streak virus from material of different three host plant species. The procedure consisted of a preliminar clarification through the adsorption of several components of the juice from diseased plants extracted with phosphate buffer at pH 8,0, 0,1, M and sodium diethyl ditbio carbamate at 0,1 M on hidrated calcium phosphate and two or more ultracentrifugation cycles. Pellets were obtained from diseased Nicotiana tubacum L. var. xanthi Solanum nigrum L. and Datura stramonium and never from the healthy control plants after two ultracentrifugations. Suspension of such pellets in phosphate buffer and sodium diethyl ditio carbamate were infectious up to the third day after the juice extraction. The purified preparations when examined under electron microscope showed particles approximately spherical with a diameter around 50 mn. The preparations obtained after the clarification and one ultracentrifugation cycle when infected daily, intravenously, in one rabbit during 7 days promoted antibody formation to the Brazilian streak virus. The presence of antibody in the antiserum could be demonstrated in gel diffusion tests, but not in precipitin tests.