[Virus-specific informosomes in tobacco cells infected with tobacco mosaic virus]

We have previously detected in TMV-infected cells virus-specific informosome-like ribonucleoproteins (vRNP) that differed in the CsCl buoyant density from mature TMV particles. It is shown in the present work that [3H]uridine-labelled TMV-specific structures, when fractionated in Cs2SO4, produce three types of structures, i. e. with a buoyant density of 1.23 g/cm3 (the so-called 1.23 material), 1.29 g/gm3 (mature virus) and 1.34--1.49 g/cm3 (vRNP). The 1.23 material has been investigated. The incorporation of [3H]palmitic acid and the sensitivity of this material to 0.1% Na dodecyl sulphate was interpreted to mean the presence of membrane components. Treatment of the 1.23 material Na dodecyl sulphate induces the release of the mature virus, vRNP and free viral RNA. vRNP was shown to contain genome TMV RNA (mol. weight, 2.0 x 10(6)) and a considerable amount of subgenomic TMV RNA (mol. weight, 1.1--1.3 x 10(6) and 0.6--0.8 x 10(6)). It is demonstrated that RNA isolated from vRNP codes for TMV-specific proteins and is able to hybridize with recombinant plasmid containing DNA-copy of 3'-end RNA TMV fragment (about one half of genome).