3. Replication
The virus, lacking the enzymes and metabolic precursors necessary for its own replication, they must obtain them from the host cell they infect. Viral replication is a process that includes several separate synthesis and subsequent assembly of all components to give rise to new infectious particles. Replication is initiated when the virus enters the cell: cellular enzymes remove the cover and the DNA or RNA is contacted with the ribosome, directing the synthesis of proteins. The virus nucleic acid autoduplicates and, once synthesized protein subunits that form the capsid, the resulting components are assembled into new viruses. A single virus particle can cause a progeny of thousands. Some viruses are released by destroying the infected cell, and yet leave the cell without destroying it by a process of exocytosis that leverages own cell membranes. In some cases the infection is ’silent’, ie the viruses replicate inside the cell without evident harm.
RNA-containing viruses are unique replicative systems, since the RNA autoduplicates without the involvement of DNA. In some cases, viral RNA functions as messenger RNA, and replicates indirectly using the ribosomal system and the metabolic precursors of the host cell. In others, the virus carried in the cover-dependent RNA enzyme that directs the synthesis process. Other RNA viruses, retroviruses, may produce an enzyme that synthesizes DNA from RNA. Formed DNA then acts as the viral genetic material. (more…)
