Category Archives: DWV

New BBSRC grant

We’re delighted to have been awarded a new BBSRC grant for studies of “The biology and pathogenesis of Deformed Wing Virus, the major virus pathogen of honeybees“. These studies will help us understand the enhanced virulence of particular strains of DWV and to determine how effective antiviral therapies may be developed.

Hives and himalayan balsam

Hives and himalayan balsam

Wood et al., 2014

Recently accepted for publication

Wood et al., (2014) MosaicSolver: a tool for determining recombinants of viral genomes from pileup data. Nucleic Acids Research (in press)

Abstract

Viral recombination is a key evolutionary mechanism, aiding escape from host immunity, changes in tropism and possibly transmission across species barriers. Determining whether recombination has occurred and the specific recombination points is thus of major importance in understanding emerging diseases and pathogenesis. This paper describes a method for determining recombinant mosaics (and their proportions) originating from two parent genomes, using high-throughput sequence data. The method involves setting the problem geometrically and the use of appropriately constrained quadratic programming. Recombinants of the honeybee deformed wing virus and the Varroa destructor virus-1 are inferred to illustrate the method, using siRNAs and sequence data sampling the viral genome population (cDNA library). Matlab software (MosaicSolver) is available.

Ryabov et al., 2014

Recently accepted for publication

Ryabov et al., (2014) A Virulent Strain of Deformed Wing Virus (DWV) of Honeybees (Apis mellifera) Prevails after Varroa destructor-Mediated, or In Vitro, Transmission. PLoS Pathogens

Abstract

The globally distributed ectoparasite Varroa destructor is a vector for viral pathogens of the Western honeybee (Apis mellifera), in particular the Iflavirus Deformed Wing Virus (DWV). In the absence of Varroa low levels DWV occur, generally causing asymptomatic infections. Conversely, Varroa-infested colonies show markedly elevated virus levels, increased overwintering colony losses, with impairment of pupal development and symptomatic workers. To determine whether changes in the virus population were due Varroa amplifying and introducing virulent virus strains and/or suppressing the host immune responses we exposed Varroa-naïve larvae to oral and Varroa-transmitted DWV. We monitored virus levels and diversity in developing pupae and associated Varroa, the resulting RNAi response and transcriptome changes in the host. Exposed pupae were stratified by Varroa association (presence/absence) and virus levels (low/high) into three groups. Varroa-free pupae all exhibited low levels of a highly diverse DWV population, with those exposed per os (group NV) exhibiting changes in the population composition. Varroa-associated pupae exhibited either low levels of a diverse DWV population (group VL) or high levels of a near-clonal virulent variant of DWV (group VH). These groups and unexposed controls (C) could be also discriminated by principal component analysis of the transcriptome changes observed, which included several genes involved in development and the immune response. All Varroa tested contained a diverse replicating DWV population implying the virulent variant present in group VH, and predominating in RNA-seq analysis of temporally and geographically separate Varroa-infested colonies, was selected upon transmission from Varroa, a conclusion supported by direct injection of pupae in vitro with mixed virus populations. Identification of a virulent variant of DWV, the role of Varroa in its transmission and the resulting host transcriptome changes furthers our understanding of this important viral pathogen of honeybees.

YBKA Spring Conference

I’m delighted to be talking  – twice (!) – at the Yorkshire Beekeepers Association Spring Conference in York on Saturday the 12th. With Stephen Martin (bee recognition and the Asian hornet), Jay Evans (beenomics – is that a real word?), Ben Jones (nutrition) and Liz Collison (neonicotinoids) also on the programme it promises to be an enjoyable day.

Update – it was a very enjoyable meeting, well attended and with two parallel sessions to entertain the audience. The sessions finished with breakout groups to “ask the experts” (or wonder where the expert was as I couldn’t find the room) followed by a wrap-up meeting. I’d like to thank the YBKA, Roger Chappel and Michael Badger for their excellent hospitality.

BBKA Spring Convention

DWV symptoms

DWV symptoms

I presented our work on honeybee viruses at the BBKA (British Beekeepers Association) Spring Convention during the Friday afternoon IPI (Insect Pollinators Initiative) research session. It was great to meet Dr. Brenda Ball who conducted some of the excellent early studies on transmission of deformed wing virus (DWV) by Varroa destructor. Also speaking at the convention was Jay Evans (USDA) who is also an invited speaker at the York Beekeepers Association Spring conference next week.