Abstract
Leaves and callus cultures from Nicotiana glutinosa L. were treated with a mixture of polyinosinic·policytidylic acid [poly(I)·poly(C)], cyclic AMP and cyclic GMP. A new antiviral activity appearing in the treated tissues co-purified with the antiviral factor AVF. Poly(I)·poly(C) can replace tobacco mosaic virus infection in the induction of AVF activity, the latter being also mediated to a certain extent by cyclic nucleotides. The kinetics of the stimulation of AVF in these in vivo studies suggests that AVF is released by a rapid activation of a pre-existing precursor, thus supporting previous results.