Effect of white spot syndrome virus infection on a Ras gene in the Chinese shrimp Fenneropenaeus chinensis

Ras is a small GTP-binding protein that is involved in the regulation of diverse cellular processes, including cell cycle progression, proliferation, and apoptosis. In the present study, a cDNA encoding Ras protein in Chinese shrimp Fenneropenaeus chinensis (designated FcRas) was cloned. The cDNA of FcRas contained a 564 bp open reading frame (ORF), five conserved regions involved in GTP metabolism, and a CAAX motif. Multiple sequence alignment showed that the C-terminal of Ras was less conserved than the N-terminal. In healthy F. chinensis, the FcRas mRNA level in the hepatopancreas and gill were both significantly (P < 0.05) higher than the level in muscle. Following challenge with white spot syndrome virus (WSSV), the FcRas mRNA level in the muscle was significantly (P < 0.05) upregulated at 48 h post-infection (hpi). In the hepatopancreas, the FcRas mRNA level was significantly downregulated at 12 hpi (P < 0.01) and 24 hpi (P < 0.05). The protein level of FcRas in the hepatopancreas was significantly downregulated at 6, 12, 24, and 48 hpi (P < 0.05). These results suggested that the FcRas expression level was influenced by WSSV infection.