RT Journal Article SR Electronic(1) A1 Zhou, Z. Sh. A1 Dell'Orco, M. A1 Saldarelli, P. A1 Turturo, C. A1 Minafra, A. A1 Martelli, G. P.YR 2006 T1 Identification of an RNA-silencing suppressor in the genome of Grapevine virus A JF Journal of General Virology, VO 87 IS 8 SP 2387 OP 2395 DO https://doi.org/10.1099/vir.0.81893-0 PB Microbiology Society, SN 1465-2099, AB Higher plants use post-transcriptional gene silencing (PTGS), an RNA-degradation system, as a defence mechanism against viral infections. To counteract this, plant viruses encode and express PTGS suppressor proteins. Four of the five proteins encoded by the Grapevine virus A (GVA) genome were screened using a green fluorescent protein (GFP)-based transient expression assay, and the expression product of ORF5 (protein p10) was identified as a suppressor of silencing. ORF5 p10 suppressed local and systemic silencing induced by a transiently expressed single-stranded sense RNA. This protein was active towards both a transgene and exogenous GFP mRNAs. Ectopic expression of GVA-ORF5 by a Potato virus X vector enhanced symptom severity. The findings that p10 markedly reduces the levels of small interfering RNAs (siRNAs) and that the recombinant protein is able to bind single-stranded and double-stranded forms of siRNAs and microRNAs, suggest the existence of a potential mechanism of suppression based on RNA sequestering., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.81893-0