Diversity in a honey bee pathogen: first report of a third master variant of the Deformed Wing Virus quasispecies

Mordecai, Gideon J; Wilfert, Lena; Martin, Stephen J; Jones, Ian M; Schroeder, Declan C

RNA viruses have rapid replication and high error rates, leading to immense diversity within each viral replication cycle (Domingo and Holland, 1997) . As a result, many RNA viruses are highly genetically heterogeneous and exist within infected population structures known as quasispecies. It has been proposed that this gives these viral pathogens an increased ability to shift to a new environmental niche, such as a new host, as a suitable mutant is more likely to already exist if this opportunity arises. However, if the diversity within a quasispecies becomes too high, deleterious mutations can accumulate leading to loss of overall fitness (Clarke et al., 1993) . The adaptability and host range of a virus are a function of the level of diversity found within a quasispecies (termed the quasispecies swarm size) (Schneider and Roossinck, 2001) . As well as a randomly generated swarm of mutants around one variant, quasispecies can also exist as a number of master variants, each with their own swarm of random mutations (Palacios et al., 2008; Lauring and Andino, 2010) . Determining the extent of genetic heterogeneity in virus populations thus has important implications for predicting and preventing emerging viral diseases.