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Abstract The widespread use of silver nanoparticles (AgNPs) has raised public concern due to their potential toxic effects on humans and the environment. Although some studies have evaluated the toxicity of nanomaterials in vertebrates, studies on their hazardous effects on insects are limited. Here we focused on different concentrations of AgNPs to silkworms, a promising model organism, to evaluate their toxic effects by omics analysis. After the silkworms were fed with 100 mg L–1 AgNPs, transcriptomics analysis showed differential expression of 43 genes: 39 upregulated and 4 downregulated. These differentially expressed genes (DEGs) were involved in the digestion process, various metabolic pathways, transmembrane transport and energy synthesis. Proteomic results for silkworms fed with 400 mg L–1 AgNPs revealed 14 significantly differentially expressed proteins: 11 downregulated and 3 upregulated. Reverse transcription–polymerase chain reaction (RT-PCR) results showed that the expression levels of eight proteins were similar to the transcription levels of their corresponding genes. As the AgNPs concentration was increased, the expression of digestive enzymes was downregulated, which damaged the silkworm tissue and suppressed the activity of the enzyme superoxide dismutase and the protein HSP 1, causing oxidative stress and the production of reactive oxygen species, which had toxic effects on the silkworm digestive system. Histopathological results showed that treatment with 400 mg L–1 AgNPs destroyed the basal lamina and the columnar cells, caused adverse effects on tissues and had the potential to induce harmful effects on the digestive system. The data presented herein provide valuable information on the hazards and risks of nanoparticle contamination. Main finding: AgNPs would downregulate some digestive enzymes, damage the tissue of midgut in silkworm, meantime induce the accumulation of reactive oxygen species which may cause oxidative stress. Graphical abstract fx1 Highlights • Silver nanoparticles at 400 mg L−1 affect the midgut structure of silkworms. • Silver nanoparticles alter the expression of genes linked to extracellular matrix receptor interactions. • Silver nanoparticles at 400 mg L−1 suppress the activity of the enzyme superoxide dismutase and the HSP 1 protein. [ABSTRACT FROM AUTHOR]

[Display omitted] • Trends of metabolite levels in silkworm hemolymph upon BmNPV treatment were revealed. • BmNPV reprogrammed metabolic pathways involving trehalose, glutamine, and tryptophan. • Tryptophan inhibited BmNPV replication while glutamine promoted it. • Trehalose and riboflavin affected BmNPV replication in a complex manner. Elucidating the mechanism of infection of Bombyx mori nuclear polyhedrosis virus (BmNPV) and host antiviral response remains a major scientific task in sericulture. Virus invasion causes a series of antiviral immune responses in the host, and successful infection leads to massive changes in the host's physiological and biochemical state. Current research mainly focuses on silkworm genes and proteins associated with viral infection and resistance, but little is known regarding the host metabolic pathways that the virus utilizes for optimal replication. In this work, key metabolites involved in viral infection were identified, including trehalose, riboflavin, tryptophan, tyrosine, and phenylalanine. The genes associated with metabolite biosynthesis and catabolism were analyzed, and their expression levels were found to be largely consistent with their respective metabolite levels before and after viral treatment in both strains. The screened metabolites were further investigated for their roles in viral replication using exogenous metabolite addition into the culture medium. The results showed that tryptophan effectively inhibited BmNPV replication, while glutamine promoted viral replication in a dose-dependent manner. Trehalose and riboflavin exhibited a complex effect on BmNPV replication. This study outlines the critical metabolites and metabolic pathways required for BmNPV to proliferate and infect the host, indicting the potential of metabolite-based treatment for viral inhibition. [ABSTRACT FROM AUTHOR]

Abstract: To investigate the molecular mechanism of silkworm resistance to BmNPV infection, we constructed a near-isogenic line (BC8) with BmNPV resistance using highly resistant (NB) and highly susceptible parental strains (306). We investigated variations in the gene expression in the midguts of BmNPV-infected BC8 and 306 at 12h pi using the microarray. 92 differentially expressed genes were identified. Real-time qPCR analysis confirmed that 10 genes were significantly up-regulated or down-regulated in the midguts of BC8 and NB compared to 306. To our knowledge, we first defined the role of the amino acid transporter and 26S proteasome in insect antiviral. However, serine protease was not completely consistent with data of reported previously in insect antiviral. The role of the 5 genes (Bm123, Bm122, COP β′, aquaporin, glycoside hydrolases) was also demonstrated in insect antiviral. Our results provided new insights into the molecular mechanism of the Bombyx mori immune response against BmNPV infection. [Copyright &y& Elsevier]

Abstract: Silkworm hemolymph is an important defense tissue to resist bacteria and virus infections. To study the response of silkworm hemolymph in the resistance of Bombyx mori L. nucleopolyhedrovirus (BmNPV), we constructed a near-isogenic silkworm line with BmNPV resistance using highly resistant and highly susceptible parental strains. In this paper, two-dimensional gel electrophoresis (2-DE) and Matrix-Assisted Laser Desorption/Ionization (MALDI)-mass spectrometry were employed to investigate the differences of protein patterns in the hemolymph of the highly resistant, highly susceptible and near-isogenic silkworm strains after BmNPV was administrated to the larvae. A comparison between the proteomes of these three silkworm strains led us to identify two differentially expressed proteins, beta-N-acetylglucosaminidase 2 and aminoacylase. The expression levels of these proteins were higher in the BmNPV resistant strains. [ABSTRACT FROM AUTHOR]

• Baculovirus proliferation inhibition was observed in BmNPV-resistant silkworm strains. • Virus gene transcription was significantly inhibited in resistant silkworm tissues. • Insect innate immunity responses contribute to BmNPV resistance at varying levels. • Antiviral activity of BmSOCS2 on BmNPV proliferation inhibition evidenced in vitro. The resistance of silkworm to infection by Bombyx mori nuclear polyhedrosis virus (BmNPV) is a main focus of sericultural research. Previously, a BmNPV-resistant strain, NB, was identified among a collection of Chinese silkworm strains in our lab. To better understand the molecular mechanism of NB strain resistance, the patterns of host immune response gene transcription in resistant (NB) and susceptible (306) strains were examined. Quantative real-time PCR (qRT-PCR) revealed that multiple insect innate immune signaling pathways (Toll, Imd and JAK/STAT) were strongly activated upon infection with BmNPV. Notably, Suppressor of cytokine signaling 2 (BmSOCS2) mRNA expression was significantly up-regulated in midgut tissues of the resistant NB strain, suggesting that the BmSOCS2 gene product may be involved in host immune defense against BmNPV infection. A significant inhibition of BmNPV replication was also observed in BmN cells transfected with a vector encoding BmSOCS2. The results suggest that BmSOCS2 is a key gene involved in the resistance of the NB silkworm strain to BmNPV infection. [ABSTRACT FROM AUTHOR]

• Large scale and precision mapping of silkworm N-glycoproteome. • Silkworm O-glycoproteins are mapped with glycosylation sites and glycan compositions. • Some glycoproteins identified are unique to the virus susceptible or resistant strains. Protein glycosylation plays important roles in protein structure, function, and immune recognition, among many other activities. One of the major roles of glycans and glycoconjugates on the cell surface is acting as the receptor for outside pathogens such as viruses. During the initial stage of viral replication, viruses interact with cell membrane receptors, which are in many cases glycoproteins. Identifying such glycoproteins is essential to understanding the mechanisms of viral infection, as well as developing antiviral strategies. Silkworm is an important economic insect as well as a model organism for molecular biology, yet current knowledge on its glycoproteome is far from complete due to both analytical challenges and perceived lack of importance. In this study, we performed a large-scale glycoproteomic survey for two silkworm Bombyx mori strains 306 and NB, which are susceptible and resistant to the baculovirus Bombyx mori nucleopolyhedrovirus (BmNPV), respectively. More than 400 silkworm N- and O- glycoproteins were identified with high confidence, demonstrating that this organism employs extensive glycosylation. We mapped some glycoproteins only to the BmNPV susceptible or resistant strain, underlining the potential relationship between glycosylation and viral susceptibility. We predicted O-glycoproteins and O-glycan compositions for the first time for this organism. The variations in glycan site occupancy, as well as glycan diversity between the two silkworm strains, provide an insight into role of glycosylation in viral recognition and infection processes. [ABSTRACT FROM AUTHOR]