AN RNA-DEPENDENT RNA-POLYMERASE ACTIVITY ASSOCIATED WITH VIRIONS OF TOMATO SPOTTED WILT VIRUS, A PLANT-INFECTING AND INSECT-INFECTING BUNYAVIRUS

An RNA-dependent RNA polymerase activity was found associated with vir ions of tomato spotted wilt virus (TSWV), a plant- and insect-infectin g member of the family Bunyaviridae. Radiolabeled nucleoside triphosph ates were incorporated into trichloroacetic acid-precipitable products by detergent-disrupted, purified TSWV virions. Incorporation was redu ced to near-background levels when RNase was present in the reaction m ixture. The predominantly double-stranded RNA products were RNase-resi stant at high but not low salt concentrations. The activity required m anganese and was independent of a DNA template. Discrete products of a pproximately 3.0 kb and heterogeneous smaller products were synthesize d that hybridized to purified TSWV RNA and transcripts of cDNA clones encompassing parts of each of the three genomic RNAs. The predominant products were viral sense although significant amounts of viral comple mentary sense S RNA products were also synthesized. (C) 1995 Academic Press. Inc.