The Antiviral Molecule 5-Pyridoxolactone Identified Post BmNPV Infection of the Silkworm, Bombyx mori

Abstract

Bombyx mori nucleopolyhedrovirus (BmNPV) is a pathogen that causes great economic losses in sericulture. Many genes play a role in viral infection of silkworms, but silkworm metabolism in response to BmNPV infection is unknown. We studied BmE cells infected with BmNPV. We performed liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS)-based non-targeted metabolomics analysis of the cytosolic extract and identified 36, 76, 138, 101, 189, and 166 different molecules at 3, 6, 12, 24, 48, and 72 h post BmNPV infection (hpi) compared with 0 hpi. Compounds representing different areas of metabolism were increased in cells post BmNPV infection. These areas included purine metabolism, aminoacyl−tRNA biosynthesis, and ABC transporters. Glycerophosphocholine (GPC), 2-hydroxyadenine (2-OH-Ade), gamma-glutamylcysteine (γ-Glu-Cys), hydroxytolbutamide, and 5-pyridoxolactone glycerophosphocholine were continuously upregulated in BmE cells post BmNPV infection by heat map analysis. Only 5-pyridoxolactone was found to strongly inhibit the proliferation of BmNPV when it was used to treat BmE cells. Fewer infected cells were detected and the level of BmNPV DNA decreased with increasing 5-pyridoxolactone in a dose-dependent manner. The expression of BmNPV genes ie1, helicase, GP64, and VP39 in BmE cells treated with 5-pyridoxolactone were strongly inhibited in the BmNPV infection stage. This suggested that 5-pyridoxolactone may suppress the entry of BmNPV. The data in this study characterize the metabolism changes in BmNPV-infected cells. Further analysis of 5-pyridoxolactone, which is a robust antiviral molecule, may increase our understanding of antiviral immunity.

Uric acid metabolism promotes apoptosis against Bombyx mori nucleopolyhedrovirus in silkworm, Bombyx mori

“…A previous study revealed that, when Sf9 ( Spodoptera frugiperda ‐9) cells were infected with the recombinant baculovirus, the purine synthesis pathway was activated and the uric acid content increased (Guillemin et al, 2020). This phenomenon was also observed in silkworms after BmNPV infection (Feng et al, 2021; Hua et al, 2021), as well as in this study, but the underlying mechanism remains unclear. In the process of uric acid synthesis, XO is an essential enzyme responsible for the conversion of hypoxanthine to uric acid and the production of H 2 O 2 during this process, which further causes ROS (Kimura et al, 2021; Odake et al, 2021).…”

“…A previous study revealed that, when Sf9 (Spodoptera frugiperda-9) cells were infected with the recombinant baculovirus, the purine synthesis pathway was activated and the uric acid content increased (Guillemin et al, 2020). This phenomenon was also observed in silkworms after BmNPV infection (Feng et al, 2021;Hua et al, 2021), as well as in this study, but the underlying mechanism remains unclear.…”

Multi-omics study and ncRNA regulation of anti-BmNPV in silkworms, Bombyx mori: an update

“…LC–MS/MS analysis indicated that in BmE cells at different infection stages (3 ~ 72 hpi), metabolite pathways were concentrated in ABC transporter, amino acid transport RNA, and purine metabolism signaling pathways ( Hua et al, 2021 ). Cluster analysis was gathered in 5-pyridoxolactone, GPC, 2-OH-Ade, γ-Glu-Cys, and hydroxybutyramide, which all showed a constant upregulation in these periods ( Hua et al, 2021 ). At the same time, only 5-pyridoxolactone strongly inhibited BmNPV replication in the phenotype experiments ( Hua et al, 2021 ).…”

“…Cluster analysis was gathered in 5-pyridoxolactone, GPC, 2-OH-Ade, γ-Glu-Cys, and hydroxybutyramide, which all showed a constant upregulation in these periods ( Hua et al, 2021 ). At the same time, only 5-pyridoxolactone strongly inhibited BmNPV replication in the phenotype experiments ( Hua et al, 2021 ). It is shown that metabolites may have a complex resistance mechanism to BmNPV.…”

“…Numerous experiments have also shown that these DEGs had resistance to the virus, or among the HSP family screened by proteomics, HSP90 had a facilitative effect on viral replication, while HSP is also regulated by a variety of ncRNAs ( Katsuma, 2021 ; Zhao Z.-M. et al, 2022 ), other proteins such as serine proteins, VTPases involved in energy metabolism were all shown to differ in the domestic silkworm ( Qin et al, 2012 ; Zhang S.-Z. et al, 2020 ), suggested a complex mechanism for the role of proteins; moreover, the strong inhibitory effect of 5-pyridolactone on BmNPV ( Hua et al, 2021 ). Also, tryptophan and 9 other amino acids were all proved to be essential to the growth and development of the silkworm and were discovered through metabolomics ( Shi et al, 2021 ).…”