Nucleopolyhedroviruses

Definition

A genus of rod-shaped, double-stranded DNA viruses in the family Baculoviridae that infect arthropods, primarily Lepidoptera larvae. NPVs produce characteristic occlusion bodies (polyhedra) containing multiple virions embedded in a crystalline matrix of polyhedrin protein; these polyhedra protect the virus in the environment and facilitate horizontal transmission when ingested by susceptible hosts. Infection typically occurs per os, with virions released in the alkaline midgut, spreading systemically and ultimately causing host liquefaction.

Etymology

New Latin, from nucleus + polyhedra (many-sided geometric solids) + virus

Example

The Thysanoplusia orichalcea nucleopolyhedrovirus is used in integrated pest management programs to control looper caterpillars on vegetable crops, with field applications of virus-killed larvae or formulated polyhedra sprayed onto foliage.

Synonyms

• NPVs
• nuclear polyhedrosis viruses

Related Terms

• Baculoviridae
• granuloviruses
• occlusion bodies
• polyhedrin
• Biological control
• entomopathogenic viruses
• viral insecticides

Usage Notes

Distinguished from Granuloviruses (GVs) by occlusion body morphology: NPVs produce many virions per polyhedron, while GVs contain single virions in smaller granules. The term is often used informally for species in the genus Alphabaculovirus (lepidopteran NPVs) and Betabaculovirus (originally 'nucleopolyhedroviruses' of sawflies). In applied entomology, 'NPV' commonly denotes specific isolates used as microbial insecticides (e.g., Helicoverpa armigera NPV, Spodoptera exigua NPV). Plural form refers to multiple species or strains; singular refers to a specific virus entity.