Vaccine for honeybees successfully completes efficacy trials

A vaccine conditionally approved by the USDA for protecting honeybees against American foulbrood (AFB) caused by Paenibacillus larvae has demonstrated efficacy in clinical trials. Based on the results of 2025 studies, the AFB vaccine from Dalan Animal Health is now closer to receiving full licensure from the federal agency’s Center for Veterinary Biologics, according to the biotech company.¹ 

"These successful efficacy trials represent a major regulatory milestone for Dalan and the beekeeping industry," Annette Kleiser, PhD, the company’s CEO and founder, said in a news release.¹ "This past summer, we performed efficacy trials similar to those we conducted for our conditional license. The results were excellent. We still have work to do before we can apply for full licensure…but this is a significant step forward in our regulatory journey."

The AFB vaccine contains killed, whole-cell P. larvae bacteria. It is administered by mixing the vaccine into queen feed that is consumed by worker bees. The vaccine is incorporated into the royal jelly by the worker bees, who then feed it to the queen. After the queen ingests this royal jelly, fragments of the vaccine are deposited in her ovaries. Having been exposed to the vaccine, the developing larvae have immunity as they hatch.²

The first-in-class AFB vaccine is non-GMO and can be used in organic agriculture. The USDA granted a conditional license for the vaccine in 2023, which has allowed it to be distributed on a limited basis to commercial beekeepers.²

The 2025 clinical trials were designed to meet USDA requirements for advancing from conditional to full licensure. The study data supporting the vaccine’s efficacy in protecting honeybee colonies from AFB is being submitted to the USDA this month for review and approval, and could receive full licensure as early as 2027. Full USDA licensure would allow the vaccine to be distributed more broadly to commercial beekeepers and enhance opportunity for it to become a standard tool in integrated pest management programs.¹

Honeybees are a critical component of agriculture. One-third of the global food supply relies on pollination, and healthy commercial hives are essential to secure high crop yields.² However, in early 2025, the Honey Bee Health Coalition revealed that beekeepers across the US had experienced catastrophic honeybee colony losses of a 62% average between June 2024 and February 2025.³

“The scale of these losses is completely unsustainable,” Zac Browning, a fourth-generation commercial beekeeper and board chairman of Project Apis m, said in a news release.⁴ “Honey bees are the backbone of our food system, pollinating the crops that feed our nation.”

It was later determined by the honeybee research organization Project Apis m that one main cause of these colony losses was deformed wing virus A and B and acute bee paralysis, which are viruses typically spread by Varroa mites.⁴

Jörg Mayer, DVM, MS, DABVP, DECZM, DACZM, professor of zoological medicine at the University of Georgia College of Veterinary Medicine in Athens, said the Varroa mite is commonly found where honeybees are. “One of the big issues is that while the bee is affected by the parasitic function of the Varroa mite—while it's feasting on the body—it also introduces a lot of viruses and other pathogens to the honeybee. Most notably is…deformed wing virus, which actually doesn't allow the bee to fly anymore, and therefore it can't provide any pollination services,” he said in a dvm360 interview at the 2025 Veterinary Meeting & Expo in Orlando, Florida.⁵

According to Dalan Animal Health, the AFB vaccine provides broad-spectrum protection. Some commercial beekeepers that used the AFB vaccine for protecting their honeybees have reported a reduction in deformed wing virus and overall improvement in the health and strength of colonies was reported.¹

According to Kleiser, Dalan Animal Health began developing the AFB vaccine at a time when honeybees were not on the veterinary industry’s radar. However, the company has grown accustomed to “pushing the boundaries of what animal health means.” Their work includes ongoing development of a vaccine to protect shrimp from common diseases. “Again, going against conventional wisdom that you can’t vaccinate shrimp because they don’t have an adaptive immune system,” she said during a panel discussion at the 2025 KC Animal Health Corridor Summit in Kansas City, Missouri.⁶

References

1. Dalan Animal Health announces successful efficacy trials for its honeybee vaccine, advancing toward full USDA licensure. News release. Dalan Animal Health. November 4, 2025. Accessed November 13, 2025. https://prnmedia.prnewswire.com/news-releases/dalan-animal-health-announces-successful-efficacy-trials-for-its-honeybee-vaccine-advancing-toward-full-usda-licensure-302603886.html
2. USDA advances American foulbrood vaccination for honeybees. dvm360. January 9, 2023. Accessed November 13, 2025. https://www.dvm360.com/view/usda-advances-american-foulbrood-vaccination-for-honeybees
3. Survey reveals over 1.1 million honey bee colonies lost, raising alarm for pollination and agriculture. News release. February 20, 2025. Accessed November 12, 2025. https://honeybeehealthcoalition.org/survey-reveals-over-1-1-million-honey-bee-colonies-lost-raising-alarm-for-pollination-and-agriculture/
4. USDA researchers find viruses from miticide resistant parasitic mites are cause of recent honeybee colony collapses. News release. June 2, 2025. Accessed November 13, 2025. https://www.ars.usda.gov/news-events/news/research-news/2025/usda-researchers-find-viruses-from-miticide-resistant-parasitic-mites-are-cause-of-recent-honey-bee-colony-collapses
5. Mayer J, Crossley KC. Varroa mites and their effect on honeybees. dvm360. January 28, 2025. Accessed November 13, 2025. https://www.dvm360.com/view/varroa-mites-and-their-effect-on-honey-bees
6. Kleiser A. Past emerging companies—where are they now. Presented at: KC Animal Health Corridor Summit; Kansas City, Missouri. August 31-September 1, 2025.