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Published on: April 12, 2017
Characterization and genome comparison of an Indian isolate of bidensovirus infecting the silkworm Bombyx mori
Tania Gupta1, Katsuhiko Ito2, Keiko Kadono-Okuda3
1Seribiotech Research Laboratory, Carmelaram-Post, Kodathi, Bangalore, 560035, India.
Abstract:
The bipartite genome of an Indian isolate of Bombyx mori bidensovirus (BmBDV), one of the causative agents of the fatal silkworm disease 'Flacherie', was cloned and completely sequenced. Nucleotide sequence analysis of this Indian isolate of BmBDV revealed two viral DNA segments, VD1 and VD2 as well as a DNA polymerase motif which supports its taxonomical status as the type species of a new family of Bidnaviridae. The Indian isolate of BmBDV was found to have a total of six putative ORFs four of which were located on the VD1 with the other two being on the VD2 DNA segment. The VD1 DNA segment was found to code for three non-structural proteins including a viral DNA polymerase as well as one structural protein, while the VD2 DNA segment was found to code for one structural and one non-structural protein, similar to that of the Japanese and Zhenjiang isolates of BmBDV. A BmBDV ORF expression study was done through real time qPCR wherein the VD2 ORF 1 and 2 showed the maximum transcript levels. This is the first report of the genome characterization of an Indian isolate of BmBDV, infecting silkworm B. mori.
Insights
This study fully sequenced the genome of an Indian Bombyx mori bidensovirus (BmBDV), identifying six open reading frames (ORFs) and supporting its classification in a new virus family. Findings advance understanding of silkworm Flacherie disease and viral genomics.
Area of Science:
- Virology
- Genomics
- Insect Pathology
Background:
- Bombyx mori bidensovirus (BmBDV) causes fatal Flacherie disease in silkworms.
- Understanding viral genomes is crucial for disease management and control.
Purpose of the Study:
- To characterize the complete bipartite genome of an Indian isolate of BmBDV.
- To analyze the genomic structure and identify potential coding regions.
Main Methods:
- Cloning and complete sequencing of the viral bipartite genome.
- Nucleotide sequence analysis to identify open reading frames (ORFs) and motifs.
- Real-time quantitative PCR (qPCR) for ORF expression analysis.
Main Results:
- The Indian BmBDV isolate possesses a bipartite genome (VD1 and VD2).
- Six putative ORFs were identified: four on VD1 and two on VD2.
- VD1 encodes non-structural and structural proteins, including a DNA polymerase; VD2 encodes structural and non-structural proteins.
- VD2 ORFs 1 and 2 exhibited maximum transcript levels in expression studies.
Conclusions:
- The genomic data supports classifying BmBDV as the type species of a new family, Bidnaviridae.
- This is the first report detailing the genome characterization of an Indian BmBDV isolate.
- The findings contribute to the understanding of BmBDV diversity and its impact on Bombyx mori.
