ichnoviruses

Ichnoviruses are a group of large, double-stranded DNA viruses that primarily infect arthropods, particularly insects and mites. They belong to the family *Ichnoviridae*, which is part of the broader order *Nucleocytoviricota*. The name "ichnovirus" derives from the Greek word *ichnos*, meaning "track" or "trace," reflecting their discovery in association with parasitic wasps that leave distinctive oviposition marks on their hosts.

Ichnoviruses are notable for their complex life cycles, which often involve horizontal transmission through the wasp's ovipositor during egg-laying. The virus infects the host insect, leading to pathological effects such as tissue disruption, which may facilitate the wasp's access to its prey. Unlike many viruses, ichnoviruses are not known to cause lytic infections in their hosts; instead, they persist in a latent state, sometimes for extended periods.

The viral genome ranges from approximately 120 to 180 kilobases, encoding numerous genes involved in replication, immune evasion, and host manipulation. Structural studies reveal that ichnoviruses possess a rod-shaped nucleocapsid enclosed within a lipid envelope, resembling baculoviruses but with distinct genetic and biological traits. They are classified into two genera: *Ichnovirus* and *Hypovirulence-associated DNA virus* (HADV), though the latter is less well-studied.

Ichnoviruses have been studied for their potential as biological control agents in pest management, though their narrow host range and complex interactions with parasitoid wasps limit their practical applications. Research into their molecular biology continues to provide insights into viral-host interactions, particularly in the context of insect immunity and symbiosis.