Nuclear polyhedrosis virus-induced proteomic changes in Antheraea mylitta

Innate immunity, the evolutionarily conserved defence system, has been extensively explored in insect models like Drosophila and mosquito species for their immune responses towards diverse pathogens. Viruses being obligate parasites take over cellular macromolecular machinery and routinely control intracellular signalling pathways through the direct or indirect control of kinases and phosphatases. Domestic silkworm, Bombyx mori is an economically important insect. Wild silkworm Antheraea mylitta produces a unique variety of silk in terms of its colour, lustre and strength called as Tasar silk. Both the silkworms vary in their immune response to nuclear polyhedrosis virus (NPV). NPV causes 80% of crop losses in B. mori, interestingly there are no documented reports of NPV infection in A. mylitta. To investigate the mechanism of A. mylitta's immune response to NPV infection, we analysed viral induced proteins through proteomic approach (SDS-PAGE and LC-MS/MS). We report the expression of a myotubularin-related protein (MTMR6) of 23 kDa at 72 h post infection (hpi) indicating its role in host immunity as a phosphatase enzyme. And also, a differentially expressed serpin-like protein of 67 kDa was upregulated in a significant way from 72 hpi further strengthening the immune response by suppressing the viral replication through serine protease inhibitory activity. This observation was further confirmed through qPCR studies on virus proliferation using lef-1 gene which clearly indicated a reduction in viral load from 72 hpi onwards in A. mylitta silkworms.

Automated summary

The study focused on the differences in immune response to nuclear polyhedrosis virus (NPV) between domestic silkworm and wild silkworm, with the latter showing no documented infection by NPV; Through proteomic analysis, the upregulation of myotubularin-related protein (MTMR6) and serpin-like protein was observed at 72 hours post infection in the wild silkworm, suggesting their involvement in host immunity and suppression of viral replication. This observation was further confirmed by qPCR studies showing a decrease in viral load in the wild silkworms from 72 hours post infection.