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Bombyx mori nucleopolyhedrovirus (BmNPV) is the most important virus that threatens sericulture industry. At present, there is no effective treatment for BmNPV infection in silkworms, and lncRNA plays an important role in biological immune response and host-virus interaction, but there are relatively few studies in silkworms. In this study, the four midgut tissue samples of the resistance strain NB (NB) and susceptible strain 306 (306) and the NB and 306 continuously infected with BmNPV for 96 h are used for whole transcriptome sequencing to analyze the differences in the genetic background of NB and 306 and the differences after inoculation of BmNPV, and the significantly different mRNA, miRNA and lnRNA between NB and 306 after BmNPV inoculation were screened. By comparing NB and 306, 2651 significantly different mRNAs, 57 significantly different miRNAs and 198 significantly different lncRNAs were screened. By comparing NB and 306 after BmNPV inoculation, 2684 significantly different mRNAs, 39 significantly different miRNAs and 125 significantly different lncRNAs were screened. According to the significantly different mRNA, miRNA and lncRNA screened from NB and 306 and NB and 306 after virus inoculation, the mRNA-miRNA-lncRNA regulatory network was constructed before and after virus inoculation, and the BmBCAT-Bomo_chr7_8305-MSTRG.3236.2 regulatory axis was screened from them, and it was found that BmBCAT was not Bomo_chr7_8305 regulated in the genetic background, after viral infection, MSTRG.3236.2 competes for binding Bomo_chr7_8305 regulates BmBCAT. The whole transcriptome sequencing results were verified by qPCR and the time-series expression analysis was performed to prove the reliability of the regulatory network. The BmBCAT-Bomo_chr7_8305-MSTRG.3236.2 regulatory axis may play a potential role in the interaction between silkworms and BmNPV. These results provide new insights into the interaction mechanism between silkworms and BmNPV. • At present, there have been studies on small RNA regulation by using sensitive silkworm varieties, but no studies have conducted whole transcriptome analysis by comparing resistant and sensitive silkworm strans inoculated with virus. • The mRNA-miRNA-lncRNA ceRNA regulatory network was constructed, from which the BmBCAT-Bomo_chr7_8305-MSTRG.3236.2 regulatory axis was screened, and the whole transcriptome sequencing results were verified by qPCR and the time-series expression analysis was performed to prove the reliability of the regulatory network. • From the perspective of lncRNA to explain the significantly different genes, our research results may provide new clues to the molecular mechanism that reveals the interaction between silkworm and virus. [ABSTRACT FROM AUTHOR]

Interacting with cell surface attachment factors or receptors is the first step for virus infection. Glycans cover a thick layer on eukaryotic cells and are potential targets of various viruses. Bombyx mori nuclear polyhedrosis viruses (BmNPV) is a baculovirus that causes huge economic loss to the sericulture industry but the mechanism of infection is unclear. Looking for potential host receptors for the virus is an important task. In this study, we investigated the role of glycosaminoglycan (GAG) modifications, including heparan sulfate (HS) and chondroitin sulfate (CS), during BmNPV infection. Enzymatic removal of cell surface HS and CS effectively inhibited BmNPV infection and replication. Exogenous HS and CS can directly bind to BmNPV virion in solution and act as neutralizers for viral infection. Furthermore, the expression of enzymes involved in GAG biosynthesis was upregulated in the BmNPV susceptible silkworm after virus administration, but down-regulated in the resistant strain after virus treatment, suggesting that BmNPV was able to utilize host cell machinery to promote the biosynthesis of GAGs. This study demonstrated HS and CS as important attachment factors that facilitate the viral entry process, and targeting HS and CS can be an effective means of inhibiting BmNPV infection. • BmNPV infection was suppressed after cell surface heparin sulfate and chondroitin sulfate were reduced. • Heparan sulfate and chondroitin sulfate can directly bind to BmNPV in solution. • GAG biosynthesis was promoted in the susceptible silkworm but suppressed in the resistant strain upon BmNPV treatment. [ABSTRACT FROM AUTHOR]

Interacting with cell surface attachment factors or receptors is the first step for virus infection. Glycans cover a thick layer on eukaryotic cells and are potential targets of various viruses. Bombyx mori nuclear polyhedrosis viruses (BmNPV) is a baculovirus that causes huge economic loss to the sericulture industry but the mechanism of infection is unclear. Looking for potential host receptors for the virus is an important task. In this study, we investigated the role of glycosaminoglycan (GAG) modifications, including heparan sulfate (HS) and chondroitin sulfate (CS), during BmNPV infection. Enzymatic removal of cell surface HS and CS effectively inhibited BmNPV infection and replication. Exogenous HS and CS can directly bind to BmNPV virion in solution and act as neutralizers for viral infection. Furthermore, the expression of enzymes involved in GAG biosynthesis was upregulated in the BmNPV susceptible silkworm after virus administration, but down-regulated in the resistant strain after virus treatment, suggesting that BmNPV was able to utilize host cell machinery to promote the biosynthesis of GAGs. This study demonstrated HS and CS as important attachment factors that facilitate the viral entry process, and targeting HS and CS can be an effective means of inhibiting BmNPV infection. • BmNPV infection was suppressed after cell surface heparin sulfate and chondroitin sulfate were reduced. • Heparan sulfate and chondroitin sulfate can directly bind to BmNPV in solution. • GAG biosynthesis was promoted in the susceptible silkworm but suppressed in the resistant strain upon BmNPV treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] Solar ultraviolet radiation (UV) can cause DNA damage in microorganisms. Flap endonuclease 1 (FEN1) is a structure-specific nuclease and plays important roles in DNA replication and repair. At present, the properties and functions of FEN1 have not been characterized in detail in invertebrates such as Bombyx mori. In this study, Bombyx mori FEN1 (BmFEN1) was expressed in E. coli, and was shown to have nuclease activity that nonspecifically cleaved DNA in vitro. However, inside the cell, BmFEN1 did not cleave DNA randomly. Truncated BmFEN1 missing the nuclear localization signal (346–380 aa) still had the nuclease activity, but was no longer precisely localized to the sites of UV-induced DNA damage. It was further found that BmFEN1 favored the faster repair of UV-damaged DNA. The present study will provide a reference for further understanding the functions of BmFEN1 and UV-induced DNA damage repair mechanisms in insects. [ABSTRACT FROM AUTHOR]