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 …
Here are answers to questions sent to virology blog about the new strain of influenza H1N1 that continues to spread globally. Q: Are you aware of efforts to make the virus strain nomenclature more informative? Understanding what segments/genes are related historically and sequence wise to what is confusing using the ‘serological’ definitions like H1N1. What …
Influenza A/Mexico/2009 (H1N1) – Questions & Answers Read More »
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 …
The influenza H1N1 outbreak in Mexico has been analyzed to provide information on the pandemic potential of the new virus strain. The estimates offer some insight into the transmissibility and severity of the virus but must be tempered with the understanding that there are still uncertainties about all aspects of the outbreak. Influenza incidence is …
Influenza A/Mexico/2009 (H1N1) virulence and transmission Read More »
The genome sequence of an RNA virus population clusters around a consensus or average sequence, but each genome is different. A rare genome with a particular mutation may survive a selection event, and the mutation will then be found in all progeny genomes. The selection process is illustrated in this diagram: The diagram on the …
