Phosphorylation of silkworm thymosin promotes the proliferation of Bombyx mori nucleopolyhedrovirus by facilitating the assembly of microfilaments

The Bombyx mori nucleopolyhedrovirus (BmNPV) poses a serious threat to the sericulture industry, and its Infection process is highly dependent on the remodeling of the host actin skeleton. When the virus infects Bombyx mori cells, it induces significant reorganization of the actin skeleton, promoting the polymerization of G-actin to form F-actin. During this process, the actin monomer-binding protein thymosin (BmTHY) can regulate the dynamic balance of the Cytoskeleton by inhibiting microfilament polymerization. Previous research by our group revealed that after BmNPV infects BmN silkworm cells, the phosphorylation level at S68 of Thymosin significantly increases (1.99 fold), suggesting that the virus may inhibit BmTHY function by altering its charge level, thereby hijacking the host microfilament network to promote its own proliferation. Subsequent experiments demonstrated that the BmTHY S68D mutation, mimicking persistent phosphorylation, reduced the binding of BmTHY to actin monomers and promoted the polymerization of G-actin into F-actin. Thus, it can be concluded that BmTHY S68D might enhance BmNPV proliferation by promoting F-actin formation.

Actin; BmNPV; Bombyx mori; Phosphorylation; Thymosin.