Polyhedra can encapsulate other proteins and have potential applications as protein stabilizers. The extremely stable polyhedra matrix may provide a platform for future engineered micro-crystal devices. However, the protein composition of the polyhedra matrix remains largely unknown. In this study, the occlusion-derived virus (ODV)-removed BmNPV polyhedra matrix fraction was subjected to SDS-PAGE and then an LC-ESI-MS/MS analysis using a Thermo Scientific Q Exactive mass spectrometer. In total, 28 host and 91 viral proteins were identified. The host components were grouped into one of six categories, i.e., chaperones, ubiquitin and related proteins, host helicases, cytoskeleton-related proteins, RNA-binding proteins and others, according to their predicted Pfam domain(s). Most viral proteins may not be essential for polyhedra assembly, as evidenced by studies in the literature showing that polyhedra formation occurs in the nucleus upon the disruption of individual genes. The structural role of these proteins in baculovirus replication will be of significant interest in future studies. The immobilization of enhanced green fluorescent protein (eGFP) into the polyhedra by fusing with the C-terminus of BM134 that is encoded by open reading frame (ORF) 134 suggested that the polyhedra had a powerful capacity to trap foreign proteins, and BM134 was a potential carrier for incorporating proteins of interest into the polyhedra.

Protein composition analysis of polyhedra matrix of Bombyx mori nucleopolyhedrovirus (BmNPV) showed powerful capacity of polyhedra to encapsulate foreign proteins.

MicroRNAs (miRNAs) constitute some of the most significant regulatory factors involved at the post-transcriptional level after gene expression, contributing to the modulation of a large number of physiological processes such as development, metabolism, and disease occurrence. This review comprehensively and retrospectively explores the literature investigating silkworm, Bombyx mori L. (Lepidoptera: Bombicidae), miRNAs published to date, including discovery, identification, expression profiling analysis, target gene prediction, and the functional analysis of both miRNAs and their targets. It may provide experimental considerations and approaches for future study of miRNAs and benefit elucidation of the mechanisms of miRNAs involved in silkworm developmental processes and intracellular activities of other unknown non-coding RNAs.

https://bioone.org/journals/journal-of-insect-science/volume-14/issue-133/031.014.133/Overview-of-Research-on-Bombyx-mori-microRNA/10.1673/031.014.133.pdf

Overview of research on Bombyx mori microRNA.

Role of microRNAs in insect-baculovirus interactions

Bombyx mori, the domesticated silkworm, is an economically important insect owing to the billion-dollar sericulture industry. It is dominant amongst the other silkworm species due to its short generation time, larger progeny size and good quality of silk fibres suitable for silk production. However, B. mori is susceptible to attack by various pathogens such as bacteria, fungi, protozoa, and viruses leading to larval mortality and causing enormous economic loss to the sericulture industry. In the past decade, microRNAs (miRNAs), a group of small non-coding RNAs that function at the post-transcriptional level, have been involved in fine-tuning many biological processes, including host-pathogen interaction. Recent studies have revealed the hitherto unknown layer of host-pathogen interaction through miRNAs in many insect species. Upon infection with the virus, the insect host produces various miRNAs that manipulate gene expression of the virus, while the virus produces several miRNAs using the host small RNA machinery to surpass the host defence mechanism and successfully infect the host. This miRNA-mediated cross-talk is a subject of study to understand better the virus infection mechanism in B. mori. The present chapter highlights various B. mori as well as pathogen-encoded miRNAs involved in host-pathogen interaction. A detailed understanding of miRNAs functioning in B. mori-pathogen interactions would undoubtedly help us design effective strategies to combat pathogen attacks on the insect population.

MicroRNAs in the silkworm-pathogen interactions

It has been shown by bioinformatic methods that regions of the Bombyx mori viral nuclear polyhedrosis genome encoded two small RNA--snc RNA-1 and snc RNA-2, which could perform a structural function in polyhedra crystals formation. The aim of this work was identification of the nucleotide sequence of small non-coding RNAs, predicted by bioinformatic methods in B. mori polyhedra. The following methods have been used: polymerase chain reaction, agarose gel electrophoresis, the cloning of PCR products, sequencing. There were first determined nucleotide sequences of snc RNA-1 and snc RNA-2 ofpolyhedrin mRNA complementary regions which are included in B. mori polyhedra. These RNAs have 100% identity with bioinformatic predicted sequences. These results confirmed our bioinformatic approach to the search for small RNAs encoded in B. mori nuclear polyhedrosis virus genome.

/pdf/identification-of-small-rna-in-polyhedra-of-bombyx-mori-16l1z22ba4.pdf

Identification of small RNA in polyhedra of Bombyx mori nuclear polyhedrosis virus

The search of miRNA genes in Bombyx mori nuclear polyhedrosis virus genome region complementary to very late genes has been carried out. The search miRNA algorithm in silico was developed by us. It was shown that NPV B. mori genome region containing orf4 gene complementary to ph gene encodes the potential miRNA. NPV B. mori genome region containing p74 gene complementary to p10 gene encodes mature miRNA and potential miRNA. The genome region containing orf1629 encodes two small non-coding RNAs complementary to orf 5'-end of polyhedrin miRNA. From obtained results it is proposed that two small noncoding RNAs complementary to regions of polyhedrin miRNA are included in polyhedra.

The search of miRNA genes in Bombyx mori nuclear polyhedrosis virus genomes regions complementary to the latest genes

It was shown that two small RNAs about 65 and 55 nucleotides long included in NPV B. mori polyhedra form with polypeptides p29 and p14 specific RNP-complexes with molecular weights of 50 and 31 kDa, respectively. Both complexes form high-molecular weight complex with polyhedrin. Origin and nature of p29 and p14 polypeptides are discussed.

Small RNAs in Bombyx mori nuclear polyhedrosis virus polyhedra form complexes with polypeptide p14 and polyhedrin

It was shown using bioinformatic approach by analysis of alternative transcriptes secondary structure, that A. californica nuclear polyhedrosis virus gene ph encoded two mature miRNAs and three potential miRNAs. Gene orf1629 complementary to gene ph did not encode miRNAs and pre-miRNA-Cs. Gene p10 encodes mature and potential miRNA. Gene p74 located on complementary chain encodes three mature miRNAs.

[The search of microRNA genes encoded in antiparallel chains of Autographa californica nuclear polyhedrosis virus genome regions, including most late and complementary genes].

By gel-filtration through Sephacryl S-300 it was shown that RNP A complex present in polyhedra of Bombyx mori nuclear polyhedrosis virus has molecular weight (M(w)) about 700 kDa. It was shown that RNP A with M(w) 788 kDa is composed of two polyhedrin 13S-associates with M(w) 342 kDa, two p14 polypeptide with M(w) 14 kDa, two 21 kDa small non-coded RNAs and two 17 kDa small non-coded RNAs. The model of RNP A formation from components making it is proposed. The complex role in the course of polyhedron formation and its role in the course of infection are discussed.

Bobrovskaia Mt

Papers

The search of miRNA genes in Bombyx mori nuclear polyhedrosis virus genomes regions complementary to the latest genes

Small RNAs in Bombyx mori nuclear polyhedrosis virus polyhedra form complexes with polypeptide p14 and polyhedrin

[The search of microRNA genes encoded in antiparallel chains of Autographa californica nuclear polyhedrosis virus genome regions, including most late and complementary genes].

[RNP-complex stoichiometry of Bombyx mori nuclear polyhedrosis virus polyhedra].