Tetherin aggregates virions and downmodulates the infectivity of the virions. Infection is also initiated by extracellular virions. Later on the enveloped virions are released to extracellular environment via exocytosis. Viruses in this family have small protein virions that exhibit T=1 icosahedral symmetry. IRF-3-knockdown cells express viral protein and produces low levels of infectious virions. Extracellular virions are cleaved by Trypsin and form mature infectious virions. The proteasome is also involved in Intracellular antibody-mediated proteolysis of antibody-bound virions. Several mRNA transcripts can be recovered from purified virions. The Z protein forms homo oligomers and a structural component of the virions. Both enveloped and unenveloped virions are infectious. With the newly formed virions, more negative sense RNA molecules are produced. CM2 may play a role in genome packaging in virions. The release of the virions occurs after the breakage of the bacterial plasma membrane. Only mature virions are then able to infect another cell. About 25 minutes after initial infection, approximately 200 new virions (viral bodies) are formed.