Quantitation of cytopathic honey bee viruses using the viral plaque assay method

Viral pathogens are highly prevalent threats to our pollination workforce. Basic virological techniques for ascertaining infection intensity and quantifying infectious viral particles lag behind the research interest in pollinator-associated viruses. Here, we utilized the only available immortalized honey bee ( Apis mellifera ) cell line, AmE-711, to establish the first plaque assay protocol for a bee-infecting virus in honey bee cells. First, we demonstrate that AmE-711 is susceptible to acute bee paralysis virus (ABPV) despite being persistently infected with deformed wing virus. Then, we compared two traditional overlays, agarose and carboxymethyl cellulose (CMC) and found that the CMC method was superior in producing countable plaques in ABPV-infected monolayers. Lastly, we demonstrated that this method was useful in quantifying infectious particle loads in lysates derived from whole honey bee pupae infected with ABPV, a field-relevant sample type.