Knockdown of BmTCP-1β Delays BmNPV Infection in vitro

Abstract

The molecular mechanism of silkworm resistance to <i>Bombyx mori</i> nucleopolyhedrovirus (BmNPV) infection remains unclear. The chaperonin containing t-complex polypeptide 1 (TCP-1) is essential for the folding of tubulin and actin to produce stable and functional competent protein conformation. However, little is known about this protein in silkworm. In the present study, a gene encoding the TCP-1β protein in silkworm was characterized, which has an open reading fragment of 1,611 bp encoding a predicted 536 amino acid residue-protein with a molecular weight of approximately 57.6 kDa containing a Cpn60_TCP1 functional domain. The sequence conservation is 81.52%. The highest level of <i>BmTCP-1β</i> mRNA expression was found in the midgut, while the lowest was in the hemolymph. To further study the function of <i>BmTCP-1β</i>, expression was knocked down with siRNA <i>in vitro</i>, resulting in significant downregulation of the selected cytoskeletal-related genes, <i>actin</i> and <i>tubulin</i>, which was also confirmed by overexpression of <i>BmTCP-1β</i> in BmN cells using the pIZT/V5-His-mCherry insect vector. Moreover, knockdown of <i>BmTCP-1β</i> significantly prolonged the infection process of BmNPV in BmN cells, which was also verified by overexpression of <i>BmTCP-1β</i> in BmN cells. Based on the results of the present study, we concluded that <i>BmTCP-1β</i> plays a vital role in BmNPV infection by regulating the expression of <i>tubulin</i> and <i>actin</i>. Taken together, our work provides valuable data for the clarification of the molecular mechanism of silkworm resistance to BmNPV infection.