Virus populations do not consist of a single member with a defined nucleic acid sequence, but are dynamic distributions of nonidentical but related members called a quasispecies (illustrated at left). While next-generation sequencing methods have the capability of describing a quasispecies, the errors associated with this technology have limited progress in our understanding of the genetic …
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The recent series of posts on polymerase error rates and viral evolution has elicited many excellent and thought provoking comments from readers of virology blog. Here is one that I had not thought of before, and which I’ll use on an exam in my virology course: Here’s a tough question. In the follow up blog …
Why don’t DNA based organisms discard error repair? Read More »
We have spent over a week discussing the effects of polymerase error rates on viruses. RNA viruses have the highest error rates in nature, a property that is believed to benefit the viral population. For example, selective pressure from the immune system or antiviral drugs may lead to changes that are beneficial for the population. …
The capacity of RNA viruses to produce prodigious numbers of mutations is a powerful advantage. But remember that selection and survival must balance genetic fidelity and mutation rate. Many mutations are not compatible with viral replication. Consequently, if mutation rates are high, at some point accumulating base changes lead to lethal mutagenesis – the population …
If you have been following our discussion of quasispecies here on virology blog, you might be wondering exactly how many possible variants there are for a viral genome. The answer is quite simple: for a genome N nucleotides in length, there are 4N possible variants, because there are 4 different nucleotides. This is a huge …
