The US Department of Agriculture (USDA) has approved the world’s first insect vaccine, developed to protect honeybees from a devastating bacterial disease known to decimate entire hives.

Insect immune systems are highly effective at targeting and eliminating pathogens. But unlike vertebrates, such as us humans, insects lack an adaptive antibody-driven immune response. This has led many scientists to suggest it may be impossible to develop vaccines for insects.

A few years ago Dalial Freitak, from the University of Helsinki, made a major breakthrough. It had been known that immunity to certain pathogens can be transferred from an insect female to her offspring but the exact molecular mechanisms at work were unclear.

Freitak and colleagues discovered a key egg-yolk protein called vitellogenin was the transport mechanism for trans-generational immunity in insects. This foundational discovery laid the groundwork for a novel kind of insect vaccine, and the team’s first target was honeybees.

Over the following years the researchers developed a vaccine to target a disease called American Foulbrood. The disease is caused by Paenibacillus larvae bacteria and once it takes hold in a bee population often the only option is to completely destroy the colony. The vaccine works by binding inactive bacterial cells to the vitellogenin protein so when it is consumed by a queen it can be directly transferred to her larvae.

“The vaccine is incorporated into the royal jelly by the worker bees, who then feed it to the queen,” a statement from developing company Dalan Animal Health explains. “She ingests it, and fragments of the vaccine are deposited in her ovaries. Having been exposed to the vaccine, the developing larvae have immunity as they hatch.”

A successful placebo-controlled clinical trial demonstrated the vaccine is both safe and effective. The offspring from a vaccinated queen bee were much less vulnerable to disease from the bacterium compared to unvaccinated offspring.

Speaking to The Guardian, entomologist Keith Delaplane envisions a system where queen bees could be vaccinated before they are transported to new hives. And entire colonies can be founded by vaccinated queens.

“In a perfect scenario, the queens could be fed a cocktail within a queen candy – the soft, pasty sugar that queen bees eat while in transit,” said Delaplane, who is working with Freitak at Dalan to help develop the vaccine. “Queen breeders could advertise ‘fully vaccinated queens.’”

The USDA’s authorization of the new vaccine marks the first time any insect vaccine has been approved for use in the United States. And for Freitak it marks just the first of a whole new array of insect vaccines helping to improve the health of bees that pollinate crops and other beneficial insects.

“Once we have tackled bee diseases we want to offer solutions for other commercially used pollinators such as bumble bees and other beneficial insects,” Freitak said in 2020. “Our goal is to offer innovative solutions in insect health in order to promote sustainable agriculture.”

Source: Dalan Animal Health