Interference of the Expression of Viral Nonstructural Protein Pns6 of Rice ragged stunt virus (RRSV) Inhibits It's Multiplication in Nilaparvata lugens
Abstract：Rice ragged stunt virus (RRSV) is transmitted by Nilaparvata lugens in a persistent propagative manner. The nonstructural protein 6 (Pns6) encoded by RRSV is a constituent of viroplasm, but the functional role of Pns6 in viral infection of insect vector is still unkown. In this study, RNA interference (RNAi) induced by synthesized dsRNAs was used to investigate the function of Pns6 in N. lugens. Second-instar nymphs of N. lugens were fed with dsRNAs targeting the Pns6 gene (dsPns6), green fluorescent protein (GFP) gene (dsGFP) or 10% sucrose diet control through a membrane-feeding method, then fed on diseased rice (Oryza sativa) plants for 2 d. At 9 d post-first access to diseased plants, immunofluorescence assay showed that the viruliferous rates of insects treated by dsGFP and 10% sucrose diet control were 27% and 30%, respectively, while the viruliferous rate of insects treated by dsPns6 was 10%. The qRT-PCR results displayed that inhibiting the expression of Pns6 could also significantly reduced (P＜0.05) the expression levels of viral structural proteins P8 and P9. In addition, the transmission rate of insects treated with dsGFP and diet control were 20% and 22%, respectively. In contrast, the transmission rate of insects treated with dsPns6 was 6%. These results revealed that Pns6 was an important protein essential for RRSV multiplication in N. lugens. Inhibition of Pns6 expression could significantly reduce (P＜0.05) the viruliferous rate and block viral multiplication, finally prevent the transmitting ability of insects. The results also confirmed that Pns6 of RRSV could act as a good target for blocking the multiplication of RRSV in its insect vector.
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