Sampling methodology and storage management effect on deformed wing virus (DWV) quantification using real-time PCR

Abstract

Deformed wing virus (DWV) is one of the most important viruses affecting Apis mellifera. A valid method for estimating the viral load at the honey bee colony level is of utmost importance. In this study, different samplings of bees were performed, in order to determine the appropriate sample size and collection point in the hive. A similar trend was observed at both sampling points, and subsequently, the DWV load was quantified in samples collected from the entire hive area. Whether 10 or 50 bees were sampled from each frame, the viral titre showed a similar dispersion and the lowest coefficient of variance was recorded in 10 bees/frame samples. According to our results, each one of the tested sampling methods can be used to quantify the viral load at the colony level, eliminating the need to sample 50 bees per frame due to the large number of bees. The effect of post-collection sample management, specifically the combination of storage temperature and duration, on RNA extraction yield, purity and virus quantification results was also investigated. The DWV titre determination was successful for all groups. It seems that improper storage affects the results of the viral quantification, however, significant differences were not observed among the treatments. Undoubtedly, immediate sample preservation in extremely low temperatures is the most appropriate method for virus analyses.

Keywords:

• DWV
• deformed wing virus
• sampling methodology
• viral load
• qPCR
• storage effect
• RNA quality

Disclosure statement

The authors report there are no competing interests to declare.