Identification of Peritrophins and Antiviral Effect of <i>Bm01504</i> against BmNPV in the Silkworm, <i>Bombyx mori</i>

• Main Authors: Xu-Le Zha, Xin-Bo Yu, Hong-Yan Zhang, Han Wang, Xian-Zhi Huang, Yi-Hong Shen, Cheng Lu
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Bombyx mori</i>; peritrophic membrane; peritrophin; <i>Bombyx mori nucleopolyhedrovirus</i>; gene editing
• Online Access: https://www.mdpi.com/1422-0067/21/21/7973

The insect midgut secretes a semi-permeable, acellular peritrophic membrane (PM) that maintains intestinal structure, promotes digestion, and protects the midgut from food particles and pathogenic microorganisms. Peritrophin is an important PM protein (PMP) in the PM. Here, we identified 11 peritrophins with 1–16 chitin binding domains (CBDs) comprising 50–56 amino acid residues. Multiple CBDs in the same peritrophin clustered together, rather than by species. The CBD contained six highly conserved cysteine residues, with the key feature of amino acids between them being CX_11-15CX₅CX_9-14CX_11-12CX_6-7C. Peritrophins with 2 and 4 CBDs (<i>Bm09641</i> and <i>Bm01504</i>, respectively), and with 1, 8, and 16 CBDs (<i>Bm11851</i>, <i>Bm00185</i>, and <i>Bm01491</i>, respectively) were mainly expressed in the anterior midgut, and throughout the midgut, respectively. Survival rates of transgenic silkworms with Bm01504 overexpression (Bm01504-OE) and knockout (Bm01504-KO) infected with <i>B. mori</i><i>nucleopolyhedrovirus</i> (BmNPV) were significantly higher and lower, whereas expression of the key viral gene, <i>p10</i>, were lower and higher, respectively, compared with wild type (WT). Therefore, Bm01504-OE and Bm01504-KO transgenic silkworms were more and less resistant, respectively, to BmNPV. <i>Bm01504</i> plays important roles in resisting BmNPV invasion. We provide a new perspective for studying PM function, and reveal how the silkworm midgut resists invasive exogenous pathogenic microorganisms.