A new twist in measuring mutation rates

Abstract

The influenza virus mutates faster than we previously thought.

Keywords: diversity; evolution; evolutionary biology; genomics; infectious disease; microbiology; mutation rate; virus.

Figure 1.. Fluorescence-reversion fluctuation test for the influenza virus.

Pauly et al. started with a recombinant influenza strain known as ΔHA-GFP in which the gene encoding the hemagglutinin surface protein (HA) had been replaced by a gene encoding a version of green fluorescent protein (GFP). This GFP gene contained a single point mutation (shown as a red circle) that prevented the protein from producing green fluorescence. The ΔHA-GFP viruses were allowed to infect mammalian cells and replicate. If, during the first round of replication, a reversion mutation occurs at the site of the original mutation (green triangle), then green fluorescence is restored to GFP. If this particular virus particle then infects a mammalian cell, its progeny virions also produce green fluorescence (bottom right). The ratio of fluorescing to non-fluorescing infected cells in the second round of infection provides an estimate of the mutation rate for this specific reversion mutation.