Cell lysis is a common outcome of viral infection. It consists of a disruption of cellular membranes, leading to cell death and the release of cytoplasmic compounds in the extracellular space.
Lysis is actively induced by many viruses, because cells seldom trigger lysis on their own. Indeed eukaryotic cells rather tend to trigger apoptosis when attacked by viruses.
Lytic replication: Most non-enveloped virus, and few enveloped viruses require cell lysis in order to release new virions from the infected cell. Cell lysis is actively induced by viruses using various mechanisms:
Viroporins: Some eukaryotic lytic viruses like the Adenoviridae, and Picornaviridae encode viroporins in the late phase of infection in order to disrupt the cell membrane.
Lytic phospholipids: Phycodnaviridae may induce the synthesis of lytic phospholipids .
Bacteria lysis: All bacterial viruses are lytic, except filamentous phages and plasmaviridae. Most bacteriophages with a complex capsid use the endolysins/holins/spanins lysis mechanism. Microviridae and Leviviridae inhibit cell wall biosynthesis and induce cytolysis.
Occasional lysis: Many viruses can induce cell lysis under special circumstance.
Occlusion body: In the late phase of host infection some viruses induce the formation of a crystalline protein matrix that ends up with cell lysis. The viruses trapped in the occlusion body are often involved in a host-to-host infection. This strategy is used by Baculoviridae, insects infecting Iridoviridae, Cypovirus and insects infecting Poxviridae.
Immune response: In vertebrate hosts, infected cell lysis can be induced by natural killer cells or cytotoxic T cells responding to the infection.