Occlusion bodies are protein lattices that protect infectious particles after release into the environment. This strategy is mostly used by insect viruses to keep long-term infectivity of tissues after the host death. At the end of infection, host-to-host virions are embedded into the protein lattice formed by the occulsion protein produced in great quantity. When the cell dies, the occlusion body persists andprotect in the long-term the infections virions. Indeed, when a larvae dies form such a virus on a leaf, occulsion bodies are deposited on it and can stay infectious until another insect arrives to eat the leaf and ingest the protected virions.
In baculoviridae and poxviridae the occlusion bodies virion is different from the normal budding virion .
Poxviridae viruses produce a kind of occlusion bodies called "A type inclusions" (ATI). Virions are embedded in the occlusion by dynamic processes requiring microtubules. .