ISHS Acta Horticulturae 431: Tospoviruses and Thrips of Floral and Vegetable Crops
ENZYME ACTIVITIES ASSOCIATED WITH VIRIONS OF TOMATO SPOTTED WILT VIRUS |
| Authors: | S. Adkins, K. Richmond, Thomas L. German |
| Abstract:
The plant-infecting members of the family Bunyaviridae, a large group of tripartite, negative-sense RNA viruses, comprise the genus Tospovirus. Tomato spotted wilt virus (TSWV), the type member of this genus, replicates in both plant hosts and thrips (Thysanoptera: Thripidae), its exclusive insect vector. Negative-sense RNA viruses encapsidate a virus-encoded RNA-dependent RNA polymerase (RdRp) that initiates the intracellular replication cycle by transcribing mRNAs from the viral genomic RNAs. RdRp activity has been detected in detergent-disrupted virions of five vertebrate-infecting members of the Bunyaviridae. Genetic analysis and the presence of conserved polymerase motifs in the greater than 200 kDa protein encoded by the L RNA of these viruses, suggest that it is responsible for the virion-associated activity. The presence of an RdRp activity associated with detergent-disrupted virions and nucleocapsids of TSWV has been demonstrated. Stimulation of RdRp activity by capped RNAs suggests that cap snatching is supported by this system. These results predict that helicase and nuclease activities might also be present. This paper describes the in vitro system we have developed and initial attempts to identify additional enzyme activities involved in replication and transcription of TSWV RNA. | |
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