Molecular characterization and expression analysis of BmNOX in two strains of Bombyx mori with contrasting viral resistance phenotype

Abstract

We recently documented the identification of a 26.5 kDa protein named BmNox in the gut fluid of Nistari strain of Bombyx mori, which possessed antiviral activity against BmNPV in vitro. In this report, we report the characterization of the full-length gene encoding BmNOX and the levels of expression of this gene in select tissues of silkworm larvae from a BmNPV-susceptible and a BmNPV-resistant strain to the defense capability in Bombyx mori larvae challenged with BmNPV. We also evaluated the BmNox expression in various stages of larval life of a resistant and a susceptible strain of Bombyx mori selected from among a panel of strains of silkworm. Nistari, a multivoltine strain of silkworm, expressed BmNOX during all five larval stages, and were highly resistant to BmNPV infection. In sharp contrast, CSR(2), a bivoltine strain, showed weaker expression of BmNOX in the anterior midgut in larval life and was highly susceptible to BmNPV infection. BmNOX is a secretory protein with dual expression in gut fluid and mid gut tissue. BmNOX is expressed heavily in the posterior mid gut, with weaker expression in the fore- and mid-gut regions.

Comparative proteomic analysis reveals that caspase-1 and serine protease may be involved in silkworm resistance to Bombyx mori nuclear polyhedrosis virus

“…Further, some proteins from silkworm showed various level of anti-BmNPV activity. The proteins purified from midgut juice of NPVresistant silkworms, such as serine protease [18] or a NADHoxidoreductase-like protein named BmNox [19], were showed to impair the virulence of NPV, suggesting that these proteins may have certain anti-BmNPV ability. Employing this method, lipase was confirmed to have anti-BmNPV activity [20].…”

Resistance to Bombyx mori nucleopolyhedrovirus via overexpression of an endogenous antiviral gene in transgenic silkworms

“…After infection with BmNPV per os, the virus is released into the midgut, where it is exposed to midgut juices containing some proteins with anti-BmNPV activity [5][6][7][8]. Bmlipase-1, a 29-kDa protein, first purified by Ponnuvel et al [5] from the digestive juice of silkworm larvae, which had lipase activity, is representative of such proteins.…”

“…Other proteins, such as B. mori serine protease-2 (BmSP-2) [6] and BmNox [7,8], were also purified from the gut juice of silkworm larvae and showed strong antiviral activity against BmNPV.…”

iTRAQ-Based Quantitative Proteomic Analysis of Digestive Juice across the First 48 Hours of the Fifth Instar in Silkworm Larvae

“…The roles of many proteins in digestive juice to resist pathogens have been investigated in silkworms. The presence of antiviral proteins, such as multiple forms of red fluorescent protein (RFPs) [17], Bmlipase-1 [22,71], dsRNase [61,62], NADPH oxidoreductase (BmNOX) [72], serine proteases (SPs), and serine protease homologs (SPHs) [16], have been previously reported. Meanwhile, RFPs, SPs, and SPHs also have antibacterial functions.…”