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The silkworm Bombyx mori ( B. mori ), a lepidopteran model organism, has become an important model for molecular biology researches with its genome completely sequenced. Silkworms confront different types of virus diseases, mainly including those caused by Bombyx mori nucleopolyhedrovirus (BmNPV), Bombyx mori densovirus type 1 (BmDNV-1), Bombyx mori bidesovirus (BmBDV) which was termed as Bombyx mori densovirus type 2 (BmDNV-2) or Bombyx mori parvo-like virus (BmPLV) before in sericulture. B. mori offers excellent models to study the molecular mechanisms of insect innate immune responses to viruses. A variety of molecules and pathways have been identified to be involved in the immune responses in the silkworm to viruses, such as the antimicrobial peptides, prophenoloxidase-activating system, apoptosis, ROS, small RNA and related molecules. Here in this review, we summarize the current research advances in molecules involved in silkworm anti-virus pathways. Moreover, taking BmNPV as an example, we proposed a schematic model of molecules and pathways involved in silkworm immune responses against virus infection. We hope this review can facilitate further study of antiviral mechanisms in silkworm, and provide a reference for virus diseases in other organisms. [ABSTRACT FROM AUTHOR]

It is unclear how, or to what extent, baculovirus DNA that has been damaged by ultraviolet (UV) light is repaired during infection and replication. In our previous study, expression of Bombyx mori nucleopolyhedrovirus (BmNPV) ORF Bm65, a homolog of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) ac79, correlated with decreased inactivation of virus by UV irradiation. In the current study, we accumulated more evidence pointing to a role for Bm65 in repair of UV-induced DNA damage. The localization of Bm65 was studied using enhanced green fluorescent protein (EGFP) fusion constructs expressed in BmN cells transfected with a Bm65 expression plasmid. The results indicate that Bm65-EGFP accumulates in the nucleus. A host cell reactivation assay showed that Bm65 significantly increased the expression of UV-damaged mCherry reporter gene. An assay measuring cyclobutane pyrimidine dimers (CPDs) in UV-irradiated BmN cells found that CPD quantity was decreased in cells transfected with a Bm65 expression plasmid. We also showed that after UVC treatment, the viability of Bm65-transfected cells was higher than that of egfp-transfected cells. These results suggest that Bm65 may be involved in the repair of baculovirus DNA that has been damaged by UV light. [ABSTRACT FROM AUTHOR]

Abstract: A gene encoding Bombyx mori arginine kinase (BmAK) has been indentified differentially expressed in the midguts of Bombyx mori strain NB which is resistant to nucleopolyhedrovirus (BmNPV), strain 306 which is susceptible to NPV and a near isogenic line BC8 with similar genetic background to 306 but resistant to NPV by two-dimensional gel electrophoresis (2-DE). In this study, we characterized the expression profiles of BmAK using RT-PCR and real-time quantitative PCR. The expression level of BmAK fluctuated in various developing stage and various tissue. Remarkably, the expression level of BmAK increased more than 10-fold 24 hours post inoculation (h p.i.) of NPV in strain NB and BC8, while such increment was abraded in strain 306 although the basal expression level of BmAK in strain 306 was higher than that of strain NB and BC8. Western blotting analysis using polyclonal antibody against BmAK verified such observation, and immunofluoresence analysis indicated for the first time that BmAK was mainly located to the cytoplasm or some structures in cytoplasm. These findings suggest that arginine kinase is involved in the antiviral process of Bombyx mori larvae against NPV infection. [Copyright &y& Elsevier]