Nudivirus

Nudiviruses are a genus of arthropod viruses that constitute the family Nudiviridae. Insects and marine crustaceans serve as natural hosts to this family of viruses. Nudiviruses are double-stranded DNA viruses, with their genome notably ranging from 130 to 140 kilobases in length. There are 20 species in this family, assigned to 4 genera. Diseases associated with this family include: death in larvae, and chronic disease in adults.

The family Nudiviridae contains the following genera:

During their first discovery, nudiviruses were classified as a subgroup in the Baculoviridae family. Originally it was assumed that nudiviruses were nooccluded baculoviruses. In 2007, the genus Nudivirus was proposed to include viruses similar to the Oryctes rhinoceros virus. In 2013, Nudiviruses were classified as the family Nudiviridae. Nudiviruses are assigned to the class Naldaviricetes that contains three other large dsDNA virus families: Baculoviridae, Hytrosaviridae and Nimaviridae.

Nudiviruses infect only insects and marine crustaceans.

Transmission of nudiviruses occurs horizontally by feeding, mating and vertically from mother to offspring. Infections can be lethal for the larvae and can possibly reduce the fitness of the host by reducing offspring production and survival among adults.

Nudiviruses are double stranded DNA viruses, characterized by their rod shape. Their virions are made of a single nucleocapsid surrounded by an envelope and range from 30 nm to 120 nm in length. They replicate in the nucleus of infected host cells and in some parasitoid wasp species, a nudivirus genome, in proviral form, is integrated into the wasp genome and produces virus like particles called polydnaviruses that are injected into lepidopteran larvae and are thought to facilitate parasitization of the larvae.

Nudiviruses have localized infection and are associated with specific cell pathogenesis and varies among species. Vesicles containing virions have been observed for HzNV-2 and OrNV and aid in infecting subsequent cells. Virions sexually transmitted during mating, like Hznv-2, target reproductive tissues, cause the malformation of reproductive tissues in infected adult Helicoverpa Zea. In cells, enveloped and non enveloped particles were observed in the nucleus and have been found to successfully replicate in infect ovarian moth cell lines, but did not replicate in fat body cells. In OrNV, replication occurs in the nucleus in midgut and fat body cells. In TpNV, replication occurs in the nucleus of the salvalary glands. The specific cell localization is a distinctive characteristic that differentiates nudivruses from baculoviruses.

Three species form Occlusion bodies (OBs), ToNV, PmNV and OrNV. In PmNV OBs are transmitted orally and are sensitive to acid conditions. Host proteins may be involved in the formation of nudiviral OBs.