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

A previous study (Highfield et al., 2009) found that despite controlling Varroa populations, high DWV loads were associated with overwintering colony losses (OCL). Historical losses due to OCL of ∼ 10% were normal; these have now risen to ∼ 20% since the establishment of Varroa. This suggests that a 'new' non-Varroa-transmitted DWV master variant may be circulating in some colonies during the winter causing OCL. To investigate this hypothesis we used a bespoke de novo assembly pipeline (Mordecai et al., 2016) . The Vicuna (broadinstitute.org/scientificcommunity/science/projects/viral-genomics/vicuna) de novo assembler was used as it is designed to assemble highly heterogeneous viral populations and is well suited to the computational challenge that the DWV quasispecies present (Yang et al., 2012) . As well as assembling the DWV type A master variant, a third DWV master variant (Type C) was assembled and confirmed to be distinct through phylogenetic inference.