Quasi-species (virology)
In virology, quasi-species is understood to mean the occurrence of different, simultaneously present variants of an originally infecting virus within the same host ( escape mutants ). The variants arise through mutations in the viral genome and selection through the reaction of the immune system.
The emergence of quasi-species in viruses that have RNA as a genome (e.g. the HI virus and the hepatitis C virus ) or use an RNA intermediate during the replication of a DNA genome (the family Hepadnaviridae e.g. the hepatitis B virus ). Through the formation of quasi-species, these viruses can constantly undermine the reactions of the immune system and develop resistance to antiviral drugs. With these viruses, mutations (and thus also quasi-species) occur primarily because the required RNA polymerases, in contrast to most DNA polymerases, do not have a correction mechanism.
The original sequence of the virus genome with which the organism was infected is usually referred to as the master sequence . Due to the emergence of quasi-species as complex virus populations and the selection acting on them by the immune system as well as the selection of quasi-species with a high rate of reproduction ( replicative fitness ), the emergence of quasi-species is also called viral microevolution . It is a kind of evolutionary race between the body's immune system and the virus population.
The concept of the quasi-species of viral RNA was first introduced into virology in 1985 as a description of the heterogeneity of nucleic acids. The term quasi-species itself is originally borrowed from the molecular evolution theory of Manfred Eigen and Peter Schuster , according to which self-replicating RNA populations are at the beginning of the development of living systems.
Individual evidence
- ↑ Domingo E, Martínez-Salas E, Sobrino F et al .: The quasispecies (extremely heterogeneous) nature of viral RNA genome populations: biological relevance - a review. Gene (1985) 40 (1): 1-8 PMID 3912262
- ^ Villarreal LP, Witzany G. Rethinking quasispecies theory: From fittest type to cooperative consortia. In: World Journal of Biological Chemistry. (2013) 4 (4): 70-79. doi: 10.4331 / wjbc.v4.i4.79