Alphabaculoviruses

Alphabaculoviruses are a genus of nucleopolyhedroviruses in the family Baculoviridae, subfamily Alphabaculovirinae. They infect insects of the order Lepidoptera, particularly caterpillars of moths and butterflies. Like other baculoviruses, alphabaculoviruses produce occlusion bodies that protect infectious virions in the environment and facilitate oral infection of larvae. The best-known member is Autographa californica multiple nucleopolyhedrovirus (AcMNPV), the type species.

Virions exist in two forms: occlusion-derived virus (ODV), enclosed in protein occlusion bodies (polyhedra), and budded virus (BV), which disseminates within the host. The genome is a circular double-stranded DNA molecule, typically around 80 to 180 kilobases, encoding hundreds of genes involved in replication, transcription, and virion assembly. Commonly studied genes include polh (polyhedrin) and p10. Infection begins when a larva ingests occlusion bodies; the alkaline gut dissolves the occlusion, releasing ODV which initiates infection in midgut cells. Progeny BV spread through the body cavity and eventually lead to production of new occlusion bodies, which are released upon death to disseminate to other hosts.

Host range is generally specific to Lepidoptera, with many alphabaculoviruses restricted to a narrow set of species, though some show broader activity. Alphabaculoviruses are used in two main applications: as environmentally friendly biopesticides against caterpillar pests in agriculture and forestry, and as vectors in the baculovirus expression vector system (BEVS) for producing recombinant proteins, including vaccines and industrial enzymes. They are considered safe for non-target organisms and vertebrates due to their high host specificity.