Ras3 in Bombyx mori with antiviral function against B. mori nucleopolyhedrovirus

Bombyx mori ras protein3 (BmRas3) is a small molecular protein in the GTPase superfamily, which has the activity of binding guanosine nucleotides and GTP enzymes. It acts as a molecular switch by coupling extracellular signal to different cellular response through the conversion between Ras-GTP conformation and Ras-GDP conformation, thus regulating signal pathways responsible for cell growth, migration, adhesion, survival and differentiation. However, few studies have been done on Ras3 in silkworm, and its function and mechanism are unclear. In this study, we found that the overexpression of BmRas3 inhibited the infection of BmNPV(B. mori nucleopolyhedrovirus), while knockdown of BmRas3 could promote the infection of BmNPV. In addition, after the BmRas3 in silkworm larvae was knockdown, the anti-BmNPV ability of silkworm decreased and the survival rate of silkworm was affected. Additionly in the cells with BmRas3 overexpression, the transcription level of BmMapkk6 ,BmP38,BmJNK,BmERK1/2 and BmERK5 were significantly increased after BmNPV infection, and the transcript levels of BmMapkk6,BmP38,BmJNK,BmERK1/2 and BmERK5 were also inhibited to varying degrees This is the first report on the antiviral effect of BmRas3 in silkworm, which provides a new direction for further study on the anti-BmNPV mechanism of silkworm and screening and cultivation of antiBmNPV silkworm strain.