Molecular biology

VIRION

Enveloped. extracellular baculovirus virions can be found in two forms: OV (occluded virus) and BV (budded virus).

GENOME

Circular dsDNA, about 82-86 kbp in length, encoding about 90 proteins.

GENE EXPRESSION

REPLICATION

NUCLEUS

1. Virus attaches to host receptors.
2. Fusion of virus membrane with the vesicle membrane occurs; DNA genome is released into the nucleus.
3. Immediate early phase: host RNA polymerase transcribes viral genes involved in the regulation of the replication cascade, prevention of host responses and viral DNA synthesis.
4. Late phase: The virally encoded RNA polymerase expresses late genes.
5. Shutdown of host cell transcription.
6. Replication of the genome by rolling circle.
7. Nucleocapsids are formed which can either bud out through the cellular membrane and disseminate the infection or be occluded for horizontal transmission.
8. Occlusion phase: the virus becomes occluded in the protein polyhedrin and the polyhedral envelope (calyx) is produced. Lysis of the cell releases the occluded virus.