An edible antiviral treatment designed for protecting honey bees — which are important agricultural pollinators — against deformed wing virus (DWV) and other viruses has been created by a team of scientists at the U.S. Department of Agriculture (USDA)'s Agricultural Research Service (ARS).

To help reduce the spread of viruses like DWV, which threaten millions of critical honey bee colonies worldwide, and subsequently pose a major risk to agriculture and the global food supply, the team discovered that engineered algae diets suppressed DWV infection, which causes both death and deformity, and thus improved survival rates in honey bees.

Engineering S2973 for in-feed delivery of dsRNA. a Integration of dsRNA expression cassettes into the S2973 genome. Cassettes produce target dsRNA with an inverted arrangement of two promoters and are flanked by sequences for homologous recombination at neutral site I (NSI). Primers used for PCR genotyping are noted. b Segregation analysis of a YFP dsRNA expression cassette. Wild type (WT) strain had a PCR product of 234 bp and no WT copy was present in strain S2973-YFP. c dsRNA production. Vector control strain S2973-NR did not express YFP RNA. dsRNA accumulation by S2973-YFP was twice that of endogenous background levels as measured by dsRNA ELISA. d Biomass production and feed formulation. Fresh S2973 biomass was mixed into a pollen-sugar paste for feeding bees. e YFP RNA stability and f relative dsRNA stability in formulated feeding treatments under colony conditions (34 °C and 50% relative humidity). g Detection of YFP RNA in bees fed S2973 diets and then sampled over time. Bee abdomens with guts intact were used for this analysis. YFP RNA was detected in bees fed S2973-YFP for at least 11 days after their last feeding (n = 16). Source: npj Sustainable Agriculture. DOI: 10.1038/s44264-024-00011-7

According to the researchers, when the engineered algae was mixed into bee food, it reportedly boosted the bee's immune system to fight off DWV, which is typically spread by Varroa mites that carry the disease and infect bee colonies.

The team worked with blue-green algae, also known as microalgae, eyeing it as a potential food source for honey bees thanks to its nutritional profile, which is similar to pollen and is scalable for commercial beekeeping.

"In addition to the nutritional benefits and immune-boosting effects, engineered algae strains have the potential to protect bees against a wide variety of pathogens," the team added.

Further, blue-green algae is grown through photosynthesis and it removes carbon dioxide from the atmosphere.

The patent-pending approach is detailed in the article “Green biomanufacturing of edible antiviral therapeutics for managed pollinators,” which appears in the journal npj Sustainable Agriculture.