Updating Sacbrood Virus Quantification PCR Method Using a TaqMan-MGB Probe

Sacbrood virus (SBV) is a common honey bee virus disease. SBV variants and strains identified in Asian honey bees, Apis cerana, have created confusion in identifications. Although the regional names indicated the expansions of the virus in new regions, pathogenesis, and genomes of these variants are not distinct enough to be a separate virus species. However, current SBV qPCR methods may not detect newly identified A. cerana SBV variants (Ac SBV) according to the genome sequences. Since these Ac SBV can naturally infect A. mellifera and possibly other hymenopterans, ignorance of Ac SBV variants in detection methods is simply unwise. In this report, we updated the qPCR method based on Blanchard's design that used conserved regions of VP1 to design a TaqMan method with an MGB (minor groove binder) probe. We tested the method in bees and hornets, including A. mellifera, A. cerana, and Vespa velutina. The updated primers and the probe can match published SBV and Ac SBV genomes in databases, and this updated method has reasonable sensitivity and flexibility to be applied as a detection and quantification method before the discovery of variants with more mutated VP1 gene.