VIRION
Enveloped. extracellular baculovirus virions can be found in two forms: OV (occluded virus) and BV (budded virus). The nucleocapsid is about 21 nm x 260 nm.
GENOME
Circular dsDNA, 80-180 kb in length, encoding for 100 to 180 proteins.
GENE EXPRESSION
The GP64 protein is expressed by leaky scanning after a uORF.
ENZYMES
- DNA primase [LEF-1]
- DNA dependent DNA polymerase [POL]
- DNA dependent RNA polymerase [DdRp]
- Alkaline nuclease [AN]
- Cell-type capping
- Peptidase C1A [VCATH]
- Metallopreotease (Peptidase M60) [VEF]
- Serine/threonine-protein kinase [PK1]
- Tyrosine-protein phosphatase [PTP]
- Chitinase [P41684]
REPLICATION
NUCLEUS
- Attachement of the viral glycoproteins to host receptors mediates endocytosis of the virus into the host cell.
- Fusion with the plasma membrane.
- The DNA genome is released into the host nucleus.
- 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.
- Late phase: The virally encoded RNA polymerase expresses late genes.
- Replication of the genome by rolling circle in nuclear viral factories.
- Nucleocapsids are formed which can either bud out through the cellular membrane and disseminate the infection or be occluded for horizontal transmission.
- 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.
