Transcriptomic analysis of Chilo iridescent virus immediate early promoter

Area of Science:

• Virology
• Molecular Biology
• Insect Pathology

Background:

• Chilo iridescent virus (CIV) belongs to the Iridoviridae family, with a fully sequenced genome but limited understanding of gene regulation.
• The CIV 012L gene's structure and transcriptional regulation are largely uncharacterized.

Purpose of the Study:

• To investigate the transcriptional regulation of the CIV 012L gene.
• To identify the promoter region responsible for CIV 012L gene expression.

Main Methods:

• Infection of Bombyx mori cells with CIV in the presence of DNA replication or protein synthesis inhibitors.
• RT-PCR and 5' RACE to analyze gene transcription and identify the initiation site.
• Reporter gene assays using luciferase to map promoter activity through sequential deletions.

Main Results:

• CIV 012L was confirmed as an immediate-early gene, with transcription starting immediately post-infection and peaking at 4 hours.
• The transcription initiation site was mapped 30 nucleotides upstream of the translational start codon.
• Promoter analysis revealed a key regulatory sequence located between -20 and -10 nucleotides relative to the transcription start site.

Conclusions:

• The CIV 012L gene exhibits immediate-early transcription kinetics.
• A critical promoter element essential for CIV 012L expression is located in close proximity to the transcription start site.
• This specific promoter sequence was not found in other potential CIV immediate-early genes.