The longer RNA species in narcissus mosaic virus encodes all viral functions

Narcissus mosaic virus (NMV) contains two nucleoprotein particles (M. N. Short and J. W. Davies, 1983, Biosci. Rep. 3, 837-846). We have fractionated the viral particles and have assayed the long (550 nm) and short (100 nm) rods for infectivity singly or in combination in several ways. The longer particle is biologically competent, as are its progeny. The RNA from the long particle encodes several products in vitro, including one which is electrophoretically and immunologically identical to coat protein. The RNA from the short particle contains about 1250 residues and, in agreement with the previous report, encodes coat protein. The sequence of this RNA is nested within that of the genomic RNA. Since the template properties of NMV can be reconciled readily with those of other potexviruses which we have examined, we believe that NMV differs from these in the encapsidation of a subgenomic mRNA for coat protein, rather than in its translational strategy.