The Autographa californica multiple nucleopolyhedrovirus lef-5 gene is required for productive infection

Area of Science:

• Molecular Virology
• Insect Pathology
• Genetics

Background:

• The Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is a significant pathogen affecting insects.
• Understanding viral gene function is crucial for controlling baculovirus infections and for applications in biotechnology.

Purpose of the Study:

• To elucidate the specific role of the AcMNPV lef-5 gene during the viral infection cycle.
• To investigate the impact of lef-5 gene deletion on viral DNA replication, gene expression, and progeny production.

Main Methods:

• Generation of an AcMNPV lef-5 knockout virus (vAc(lef5ko)).
• Creation of a complementing cell line for viral replication studies.
• Analysis of viral DNA replication, early and late gene expression (including reporter gene assays), and infectious viral progeny production.
• Rescue experiments using egfp- or myc-tagged lef-5 genes and generation of a stable Sf9 cell line expressing an egfp-tagged lef-5 gene from SeMNPV.
• Immunofluorescence to determine LEF-5 protein localization in infected cell nuclei.

Main Results:

• AcMNPV DNA replication and early gene expression were unaffected by the absence of the lef-5 gene.
• Expression of late viral genes and production of infectious viral progeny were significantly impaired in the lef-5 knockout virus.
• Complementation with tagged lef-5 genes restored viral replication and progeny production, confirming the gene's essential role.
• The LEF-5 protein was observed to co-localize with the IE-1 protein in the nucleus of infected cells.

Conclusions:

• The AcMNPV lef-5 gene is indispensable for efficient late gene expression and the production of infectious viral progeny.
• LEF-5 plays a critical role in the late stages of the baculovirus infection cycle.
• LEF-5 functions in the nucleus and potentially interacts with other viral proteins like IE-1.