Three members of Ras GTPase superfamily are response to white spot syndrome virus challenge in Marsupenaeus japonicus

• Three types of small GTPase genes (MjRap, MjRas, and MjRal) from Marsupenaeus japonicus were identified.
• MjRal was regulated by White spot syndrome virus.
• The RNAi of MjRal could inhibit the WSSV replication, but had no effect on VP28 expression.

Members of the Ras-like GTPase superfamily are key regulators of diverse cellular and developmental events, including differentiation, cell division, vesicle transport, nuclear assembly, and cytoskeleton control. In this study, three Ras family members (MjRap, MjRas, and MjRal) were cloned from Marsupenaeus japonicus. The full lengths of MjRap, MjRas, and MjRal are 788, 1330, and 2074 bp, which encode the proteins of 186, 202, and 198 amino acids respectively. Phylogenetic analysis showed that Rap, Ras, and Ral from different species gather together. The MjRap, MjRas, and MjRal genes were ubiquitously expressed in the hemocytes, hepatopancreas, gills, stomach, and muscle. Results from the quantitative real-time polymerase chain reaction (qRT-PCR) showed that MjRal in the gills was upregulated 48 and 72 h post-White spot syndrome virus (WSSV) challenge. No change in the MjRap or MjRas transcript was observed in the gills under the WSSV challenge. The RNAi of MjRal could enhance the WSSV replication. Injection of rMjRal protein could inhibit WSSV replication, but had no effect on VP28 expression. So, it could be concluded that MjRal was involved in shrimp anti-viral innate immune defense by inhibiting the WSSV replication.