Identification and functional characterization of a systemic RNA interference defective 1 gene in Litopenaeus vannamei

RNA interference (RNAi) is a conservative and important functional pathway in eukaryocyte. It regulates the expression of genes that are engaged in a variety of cellular physiological functions. Among the functions of RNAi, its antiviral function have attracted many attentions.The RNAi pathway molecules are able to recognize virus-related dsRNA and degrade it, therefore killing the virus. More importantly, RNAi could mediate systemic antiviral responses, transmit from cell to cell, and systemic RNA interference defective 1 (SID1) was thought to play an important role in this process. In the present study, a SID1 gene (LvSID1) of Litopenaeus vannamei was cloned. LvSID1 could locate to both plasma membrane and endoplasmic reticulum. Result of real-time RT-PCR assay showed that it was highly expressed in shrimp gills. Besides, it was shown that over-expressed LvSID1 in Sf9 cells could significant enchane RNAi efficiency. It was found that the expression of LvSID1was regulated by white spot syndrome virus (WSSV), and knockdown expression of LvSID1 increased the cumulative mortality of WSSV infection shrimp. These results suggested that LvSID1 likely to played a role in L. vannamei systemic RNAi, and was involved in WSSV resistence.