This chapter reviews information concerning the mechanisms of sources of new variation,
returning at the end to ask if the genetic new information sheds any additional light on the …

Many RNA viruses have been known for decades to be genetically and biologically quite
variable. Some well-known examples are influenza viruses, foot and mouth disease viruses …

Each clone of ts-52 and ts+ WSN influenza virus, when serially passaged at high multiplicity,
gives rise to defective interfering (DI) virus with a unique set of new RNA species. The new …

It is well known that the dinucleotide CpG is under-represented in the genomic DNA of many
vertebrates. This is commonly thought to be due to the methylation of cytosine residues in …

Influenza virus was the first virus for which defective-interfering particles were reported. Von
Magnus (1947) observed that when he passaged influenza viruses serially undiluted in …

RNA virus quasispecies are subjected to processes of positive Darwinian selection, to a very
active and continuous negative selection and to random genetic drift. The course of RNA …

The mechanisms of evolution of RNA virus genomes have recently received less attention
than the evolution of DNA genomes (or of RNA retroviruses able to reverse-transcribe their …

We review evidence that cloned (or uncloned) populations of most RNA viruses do not
consist of a single genome species of defined sequence, but rather of heterogeneous …

RNA genomes have been shown to mutate much more frequently than DNA genomes. It is
generally assumed that this results in rapid evolution of RNA viral proteins. Here, an …

The most abundant viruses infecting plants, animals and humans are the RNA viruses
(riboviruses and retroviruses). These elemental life forms are hypervariable to a degree that …