Bombyx mori nucleopolyhedrovirus : Characterization of Late Gene Expression factors,lef4 and p47

Abstract

Characterization of Late Gene Expression Factors LEF4 and P47 in Bombyx mori Nucleopolyhedrovirus (BmNPV)

Abstract and Synopsis Introduction A recurrent threat to the sericulture industry is the infestation of colonies by infectious agents. One of the major pathogens of the mulberry silkworm (Bombyx mori) is the nucleopolyhedrovirus BmNPV, belonging to the family Baculoviridae.

While baculoviruses have been used as biocontrol agents against agricultural insect pests, in the last decade they have gained prominence as expression vectors for producing recombinant proteins in large quantities. The strong promoters of viral very late genes, polyhedrin (polh) and p10, are widely employed in baculovirus-based expression vector systems (BEVS). Post-translational modifications of baculovirus-expressed proteins closely resemble those in mammalian cells, making them valuable for biotechnology and medical applications.

The most extensively studied baculovirus is Autographa californica multinucleocapsid polyhedrovirus (AcMNPV), which serves as the prototype for molecular studies and recombinant protein expression. Next to AcMNPV, the Bombyx mori nucleopolyhedrovirus (BmNPV) has gained economic importance, particularly for over-expression of cloned foreign genes in larval caterpillars.

Baculovirus Gene Expression

Gene expression occurs in three phases: early, late, and very late.

Early genes are transcribed by host RNA polymerase II.

Transition to late gene expression involves a switch to an -amanitin-resistant viral RNA polymerase.

In AcMNPV, late gene expression factors (LEFs) have been identified, including LEF9, LEF8, LEF4, and P47, which form the viral RNA polymerase complex.

Genomic sequencing of BmNPV has revealed counterparts of these LEFs, but their functional characterization remains limited.

Objectives of the Present Study

Clone LEF4 and study its temporal expression profile at RNA and protein levels in BmNPV-infected BmN cells, including intracellular localization.

Perform detailed biochemical characterization of the LEF4 protein.

Clone P47 and study its temporal expression profile in BmNPV-infected BmN cells.

Analyze the effect of antisense LEF4 and P47 expression on viral very late gene expression.

Conclusions This study focuses on the molecular characterization of LEF4 and P47, two critical late gene expression factors in BmNPV.

Understanding their temporal expression and functional roles will provide insights into the transcriptional regulation of baculoviruses.

The findings contribute to both basic virology and applied biotechnology, particularly in optimizing baculovirus-based expression systems.