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Published on: August 26, 2020
Molecular Characterization and Phylogenetic Analysis of Honeybee (Apis mellifera) Mite-Borne Pathogen DWV-A and DWV-B
Paulina Amšiejūtė-Graziani1,2, Vaclovas Jurgelevičius1, Simona Pilevičienė2
1Faculty of Natural Sciences, Vytautas Magnus University, Universiteto str. 10, Akademija, Kaunas District, LT-44248 Kaunas, Lithuania.
Abstract:
Deformed wing virus (DWV) is known as one of the main viruses that affect honeybees' health all around the world. The virus has two widespread genotypes, DWV-A and DWV-B (VDV-1), transmitted mainly by V. destructor mites. In this study, we collected honeycombs with covered broods from 73 apiaries in eight Lithuanian regions and initially investigated the prevalence of V. destructor mites. Mites were collected from May to the end of July in 2021 from 124 hives. The prevalence of V. destructor infestations in beehives reached 30% and 63% in investigated apiaries. The presence of DWV-A and DWV-B pathogens in mites and broods was examined by RT-qPCR targeting the CRPV-capsid region. The molecular characterization of the virus in mite samples was based on sequence analysis of the RNA-dependent RNA polymerase (RdRp) region. In addition, leader polypeptide (LP), structural protein (Vp3), Helicase, and RdRp genes were used for phylogenetic characterization of dual infection. The prevalences of DWV-B in mites and broods were 56.5% and 31.5%, respectively, while DWV-A was detected in 12.9% of mite samples and 24.7% of brood samples. Some of the examined mite samples harboured dual virus infections. Our findings showed that bee colonies from the same apiary were not always infected by the same viruses. Some bee colonies were virus-free, while others were highly infected. Phylogenetic analysis of 21 sequences demonstrated the presence of highly variable DWV-B and DWV-A genotypes in Lithuania and possible recombinant variants of the virus. This study represents the first molecular characterization of mite-borne pathogens hosted by honeybees (Apis mellifera) in Lithuania.
Insights
Deformed wing virus (DWV) affects honeybees globally. This study found prevalent Varroa mites carrying diverse DWV-A and DWV-B genotypes in Lithuania, including dual infections and potential recombinants.
Area of Science:
- Apiculture
- Virology
- Molecular Biology
Background:
- Deformed wing virus (DWV) is a major honeybee pathogen worldwide.
- DWV exists as genotypes DWV-A and DWV-B (VDV-1), primarily transmitted by Varroa destructor mites.
Purpose of the Study:
- To investigate the prevalence of Varroa destructor mites and DWV genotypes (DWV-A and DWV-B) in honeybees across Lithuania.
- To perform molecular and phylogenetic characterization of DWV strains found in mites and broods.
Main Methods:
- Collection of mites and honeybee broods from 73 apiaries in eight Lithuanian regions.
- Prevalence assessment of Varroa destructor infestations.
- Detection and quantification of DWV-A and DWV-B using RT-qPCR.
- Molecular characterization via sequence analysis of viral genes (RdRp, LP, Vp3, Helicase).
- Phylogenetic analysis of viral sequences.
Main Results:
- Varroa destructor infestation prevalence reached 30% in apiaries and 63% in hives.
- DWV-B was detected in 56.5% of mites and 31.5% of broods; DWV-A in 12.9% of mites and 24.7% of broods.
- Dual infections of DWV-A and DWV-B were found in some mite samples.
- Phylogenetic analysis revealed highly variable DWV genotypes and potential recombinant variants in Lithuania.
Conclusions:
- This study provides the first molecular characterization of mite-borne DWV in Lithuania.
- Significant genetic diversity of DWV-A and DWV-B, including potential recombinants, circulates in Lithuanian honeybee populations.
- Infection patterns varied within apiaries, with some colonies virus-free and others heavily infected.
