Detection of rice grassy stunt tenuivirus nonstructural proteins p2, p5 and p6 from infected rice plants and from viruliferous brown planthoppers.

摘要

The genome of Rice grassy stunt virus (RGSV) consists of 6 ambisense RNA segments, among which RNAs 1, 2, 5 and 6 are equivalent to RNAs 1, 2, 3 and 4, respectively, of Rice stripe virus, the type species of the genus Tenuivirus. The RGSV 36-kDa nucleocapsid protein (N) is encoded on the complementary strand of RNA 5. Here, we studied accumulation of three nonstructural proteins, a 23-kDa p2 protein encoded on vRNA 2 (virus genomic strand), a 22-kDa p5 protein encoded on vRNA 5, and a 21-kDa p6 protein encoded on vRNA 6, from RGSV-infected rice leaf tissues and from viruliferous vector insects (brown planthopper, Nilaparvata lugens) by Western blot analyses. p2, p5 and p6 were detected from RGSV-infected rice leaf homogenates; p2 was detected mostly in the cytoplasmic soluble fraction but also a small amount was detected in the cell-wall, organelle-enriched and crude membrane fractions; p5 and p6 were detected from the cytoplasmic soluble fraction in large amounts. Among individual nymphs of N. lugens raised on RGSV-infected rice leaves, only 20% of insects were positive with the N protein. A large amount of p5 was detected from all the N-positive insects. Small amounts of p2 and p6 were detected only from a subset of the N- and p5-positive insects. p5 may have an essential role in virus infection in both plant and insect hosts, whereas p2 may function in plants such as a cell-to-cell movement protein.