Abstract: When the white-backed planthopper (Sogatella furcifera) acquires Southern rice black streaked dwarf virus(SRBSDV) by feeding on SRBSDV-infected rice, the SRBSDV binds to receptors on the cell membrane and enters the host cell via clathrin-dependent endocytosis. Cathepsin D (CathD) is an aspartic protease, which is involved in the process of endosome/lysosomal protein degradation and viral release into the cytoplasm. However, it is unclear whether CathD plays a role in SRBSDV infection of white backed planthopper. RNA interference (RNAi) was used to silence the expression of CathD gene in the white-backed planthopper. The results showed that knocking down the mRNA expression level of CathD in the white-backed planthopper and subsequently SRBSDV feeding did not affect the survival rate of the white-backed planthopper, however, the viral carrier rate and viral quantity in the white-backed planthoppers were decreased. Meanwhile, knockdown the expression of the homologous CathD gene in Drosophila cells decreased DCV replication significantly compared with that of the control group. The results demonstrated that CathD may assist virus proliferation and replication in insects using a conserved mechanism, suggesting that CathD might be a potential target protein for the prevention and control of SRBSDV disease.

Key words: white-backed planthopper, RNAi, endocytosis, SRBSDV, CathD