baculovirus

Baculoviruses are a family of large, double-stranded DNA viruses that infect insects, particularly caterpillars. They are enveloped virions with rod-shaped nucleocapsids and relatively large genomes, typically 80 to 180 kilobases in length. The family Baculoviridae is divided into four genera: Alphabaculovirus, Betabaculovirus, Gammabaculovirus, and Deltabaculovirus. Alphabaculoviruses and Betabaculoviruses primarily infect lepidopteran hosts, while the other genera include viruses with broader or different insect associations. Each virus forms occlusion bodies called polyhedra (NPV) or granules (GV) that protect virions in the environment.

Life cycle: Infection begins when a larva ingests occlusion bodies. In the alkaline gut, occlusion-derived virions are released and infect gut epithelial cells (primary infection). The virus then spreads systemically via budded virus; later, nuclei produce new virions and occlusion bodies accumulate, which are released upon the host’s death and disperse to infect new hosts.

Applications: Baculoviruses are used as environmentally friendly, host-specific biopesticides against pest caterpillars. Several commercial products are based on NPVs and GVs for crops in fruit and vegetable production. In the laboratory, the baculovirus expression vector system (BEVS) uses Autographa californica multiple nucleopolyhedrovirus (AcMNPV) or related viruses to drive high-level expression of foreign genes in insect cell cultures, enabling production of recombinant proteins, vaccines, and viral antigens.

Safety and research: They pose limited risk to humans and vertebrates but require regulatory oversight for environmental release and laboratory use. Baculovirus systems remain a foundational tool in molecular biology and biotechnology.