Baculoviruses

Baculoviruses are a group of large double-stranded DNA viruses in the family Baculoviridae that infect insects, particularly lepidopterans. They are enveloped, rod-shaped virions with circular dsDNA genomes typically 80–180 kilobases in length and encoding around 90–180 genes.

The family is divided into four genera: Alphabaculovirus and Betabaculovirus, which predominantly infect lepidopteran hosts, and Deltabaculovirus and Gammabaculovirus, found in other insect groups. The two major virion forms produced during infection are budded virus, which disseminates the infection within the host, and occlusion-derived virus, which is packaged into occlusion bodies (polyhedra or granules) that protect virions outside the host and enable oral infection when ingested.

Infection typically begins when a larva ingests occlusion bodies. The alkaline insect gut dissolves the occlusion bodies, releasing ODVs that infect midgut epithelial cells. Budded viruses then spread systemically to other tissues. Later, infected cells produce new occlusion bodies, which accumulate in the cadaver and are released into the environment, ready to infect new hosts.

Applications of baculoviruses include their use as environmentally targeted biological pesticides. Species such as codling moth granulovirus (CpGV) and Autographa californica multiple nucleopolyhedrovirus (AcMNPV) are employed in pest management. The baculovirus expression vector system (BEVS) uses recombinant baculoviruses to express foreign proteins in insect cells and is widely used for producing vaccines, therapeutic proteins, and virus-like particles.