“Vaccines” for Honeybees and Shrimp?

Researchers are investigating whether feeding inactivated bacteria to invertebrates such as honeybees and shrimp can act as “vaccines” by causing epigenetic changes that prevent disease, even though invertebrates lack the immune system typically targeted by traditional vaccines.¹

The first vaccine for honeybees has received conditional approval from the U.S. Department of Agriculture in 2023 and has begun rolling out on farms in the United States and Canada. The company behind that vaccine, Dalan Animal Health, based in Athens, Georgia, recently announced early results from tests of a potential vaccine for shrimp at the World Vaccine Congress in Washington, DC.²

Researchers say they are studying whether vaccines can help address diseases that affect honeybees and shrimp.^{3 4} Disease and pests contribute to significant economic losses in the beekeeping industry, which is valued at more than $10 billion. Diseases also cost the shrimp sector, worth tens of billions of dollars, several billion dollars annually. Scientists are testing whether boosting immune responses in these animals can help limit disease and reduce antibiotic use.⁵

Vaccination Without an Adaptive Immune System

Unlike humans and other vertebrates, invertebrates do not have an adaptive immune system that produces antibodies in the blood against specific pathogens. Instead, they rely on innate cellular immunity, which responds more broadly to threats and has historically not been the main target for trying to make vaccines effective.⁶

For many years, scientists believed vaccination would not be possible in invertebrates because of their lack of an adaptive immune system. However, researchers have found evidence that innate immunity may be capable of developing a form of immune memory through epigenetic changes, which modify how genes function  (get turned on or off) without altering the underlying DNA sequence. Scientists also believe these epigenetic changes can be passed from one generation to the next, forming the basis of Dalan’s vaccine approach.⁷

Honeybees and Disease Resistance

The existing honeybee vaccine contains inactivated Paenibacillus larvae, the bacterium responsible for American foulbrood, a disease that infects and kills honeybee larvae. Researchers feed the honeybee vaccine to queen bees, and when those queens reproduce, their offspring show increased resistance to the bacteria.

Researchers have also observed resistance in offspring to a virus associated with varroa mites after the queen receives the vaccine The honeybee vaccine is one of the first commercial applications of this approach in an invertebrate species.⁸

Early Results From Shrimp Vaccine Research

Dalan is applying a similar strategy to shrimp. According to the company, the vaccine uses inactivated bacteria that are fed to the maternal broodstock, allowing the resulting offspring to inherit disease resistance. As a result, researchers believe the next generation of shrimp will be born with protection against certain pathogens.⁹ Researchers view this approach favorably because shrimp are raised in such large numbers that administering individual injections would be impractical.¹⁰

Laboratory testing exposed vaccinated shrimp to Vibrio parahaemolyticus, a bacterium that causes Early Mortality Syndrome (EMS), and to White Spot Syndrome Virus (WSSV). In these trials, survival increased from 27 percent to 48 percent among shrimp exposed to Vibrio parahaemolyticus. For shrimp exposed to WSSV, survival increased from zero percent to 58 percent.^{11 12}

Further Research Needed

Despite the early findings, some researchers say additional evidence is needed. Arun Dhar, PhD,  a crustacean infectious disease researcher at the University of Arizona, said that he would like to see the results published in a peer-reviewed paper before assessing their potential. He stated that his long-standing work in crustacean pathology has led him to take a cautious view of proposed vaccine candidates: “Field data would really indicate the true efficacy.”¹³

Dalan plans to begin field trials in Southeast Asia, starting in Indonesia, to gather additional data and support future regulatory review.¹⁴

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