Functional Study Of The Cuticular Protein CPR1 Involved In Rice Stripe Virus Transmission By Small Brown Planthopper

Rice stripe virus (RSV), is mainly transmitted by the small brown planthopper (SBPH) (Laodelphax striatellus) in a persisent-propagative manner to the host plant, and has been transmitted to the next generation trough eggs. The successful virus transmission requires specific interactions between the viral nucleocapsid protein (pc3) and unknown components of the insect vector to allow transport of the virus movement and replication in insect tissues. Based on the yeast two-hybrid results, many L. striatellus proteins were interacted with RSV pc3. A novel cuticular protein CPRlof L. striatellus was chosed for further functional study. Firstly, the full length gene of CPR1 was obtained by RACE. Interaction of RSV pc3 and CPR1 was confirmed by Co-IP assay. Secondly, it was clarified the interacted domain of CPR1 with RSV pc3 by yeast two hybrid and pull down assay. Then mRNA level of CPR1 was detected by qRT-PCR; which was highly accumulated in the hemolymph. This study provides evidence that CPR1 and RSV can colocalize each other in the hemocytes of L. striatellus. After injection with CPR1 dsRNA, RSV pc3 was significantly reduced in the hemolymph and salivary glands of L. striatellus. Inhibition of CPR1 expression also resulted in a decrease in viral transmission efficiency more than 50%. These data suggest that CPR1 binds RSV in the insect and stabilizes the viral concentration from degradation in the hemolymph. Our studies provide direct experimental evidence that viruses can use existing vector proteins to aid their survival in the hemolymph.