Ribosomal protein L18 is an essential factor that promote rice stripe virus accumulation in small brown planthopper

Rice stripe virus (RSV) transmitted by the vector, small brown planthopper (SBPH), can cause a severe rice disease. The nucleocapsid (N) protein is the major component of RSV ribonucleoprotein particles (RNPs), and it plays important roles in viral persistent-propagative transmission by SBPH. To gain further insights into the vector components enabling RSV transmission, a GAL4-based yeast two-hybrid system was utilized to find unknown vector factors that interact with the N protein. Thirteen different proteins were identified as factors that interact with the N protein. The interaction between 60S ribosomal protein L18 (RPL18) and the N protein was further studied. Although the expression of RPL18 was not altered in insects during RSV infection, RPL18 was validated to bind directly to RSV RNPs and interact with RSV N protein. Knockdown of RPL18 dramatically reduced viral RNA and protein levels, especially viral protein expression, indicating a requirement for RPL18 in RSV translation and replication. Our results provide evidence that RPL18 is a critical factor required for RSV accumulation in SBPH, which suggests that the vector factor RPL18 may be as a potential target to develop for controlling the transmission of rice virus.