Is the quasispecies concept relevant to RNA viruses?

The most basic evidence presented in favor of the quasispecies is that populations of RNA viruses are highly variable.

What happens when RNA viruses replicate above their error threshold?

Beyond this threshold, so many deleterious mutations occur during each replication cycle that ‘fit’ viral genomes are unable to reproduce themselves faithfully and the population eventually becomes extinct. RNA viruses are therefore permanently close to ‘error catastrophe’.

Why do RNA viruses mutate faster?

The pace of evolution The RNA polymerase that copies the virus’s genes generally lacks proofreading skills, which makes RNA viruses prone to high mutation rates—up to a million times greater than the DNA-containing cells of their hosts.

How does helper virus work?

A helper virus is a virus that allows an otherwise-deficient coinfecting virus to replicate. These can be naturally occurring as with Hepatitis D virus, which requires Hepatitis B virus to coinfect cells in order to replicate.

How are quasispecies related to the behavior of RNA viruses?

RNA viruses exist as a quasispecies. A virus replicating with a high mutation rate will generate a diverse mutant repertoire over the course of a few generations. In these trees, each branch indicates two variants linked by a point mutation and the concentric circles represent serial replication cycles.

How are quasispecies related to the origin of life?

Fueled by high mutation rates, mutants arise continually, and they change in relative frequency as viral replication proceeds. The term quasispecies was adopted from a theory of the origin of life in which primitive replicons) consisted of mutant distributions, as found experimentally with present day RNA viruses.

What are the mechanisms of persistence of RNA viruses?

Most of the well-studied mechanisms of persistence of RNA viruses in primary cell cultures or established cell lines involve genetic variation of the virus, the cell, or both. One way to limit cell death is by generating and accumulating defective genomes.

What kind of viruses have high mutation rates?

A large number of medically important viruses, including HIV, hepatitis C virus, and influenza, have RNA genomes. These viruses replicate with extremely high mutation rates and exhibit significant genetic diversity.