The discovery of RNA transfer via royal jelly could help develop vaccines for honey bees

The researchers discovered that honey bees can share immunity with other bees and their offspring in a hive by transmitting "vaccines" based on RNA via the royal jelly and working jelly. Jelly is the equivalent of the mother's milk bee: a secretion used to feed working and queen larvae.

The findings suggest new ways to protect bees against viruses and deadly mites that have been responsible for the recent dramatic decline in honeybee populations. As about one-third of the world's food depends on pollination by honey bees, we urgently need solutions to help maintain thriving honeybee colonies for our food security and sustainability.

Eyal Maori of Wellcome Trust / Cancer Research UK at the Gurdon Institute, University of Cambridge, and colleagues in Israel and the United States have experimented with a new type of antiviral treatment for bees when they get the impression that these bees could transmit biologically active RNA molecules between members of the colony. Scientists are now publishing evidence of such a phenomenon of bee-to-bee RNA transfer in the journal Cell reports.

These transmissible RNA molecules are produced by bee genes and by pathogens such as viruses. Unlike other RNAs in the body, these RNA molecules do not code for proteins. Instead, they play a direct role in immunity, regulation of genes, and other biological mechanisms.

In previous studies, Dr. Maori and his colleagues fed bees with RNA fragments comprising a segment of an RNA virus. They found that, as with vaccines, RNA activated an immune response that prevented disease and death when the urticaria was subsequently exposed to the live virus. Curiously, the colony maintained a healthy performance for several months after the end of treatment, suggesting that she was still immune to infection, even though the bees initially treated would have perished and have been replaced by new generations. . This suggests that the immunizing RNA fragments have been transmitted to members of the colony as well as to all generations.

In the study published today, researchers have demonstrated that dietary RNA is absorbed by the ingestion system into the circulatory fluid of the bee and spreads to the secreting glands. jelly. The food RNA is then secreted with the jelly and taken up by the larvae fed with the jelly.

Although scientists have already shown in plants and animals that it is possible to circulate RNA between cells of an organism, these findings make it possible to identify a molecular mechanism for the transmission of RNA molecules between organizations.

"We found that RNA spread beyond isolated honeybees, being transferred not only between parents and their offspring, but also between individuals in the hive," says Dr. Maori.

Other experiments have shown that transmissible RNA was able to activate a mechanism called "RNA interference" in order to block the activity of certain genes and to reduce the production of some proteins of the bee. It is important to note that interference from RNA is known to provide a defense against viral infection in bees and other organisms. In other words, these molecules of RNA probably act to immunize bees against infections.

The researchers then analyzed worker and royal jellies and revealed various types of naturally occurring RNA, some bee gene derivatives and some other pathogens such as fungi and infectious viruses, suggesting that over time the bees had developed and shared immunity against these pathogens. .

"Our results demonstrate that bees share a" transmissible RNA "between members of the colony, probably as a means of sharing immunity between members and generations of the hive and allowing other bees to adapt to different environmental conditions, "commented Dr. Maori.

In a second study, published last month in the journal Molecular Cell, Dr. Maori, in collaboration with Professor Eric Miska's lab at the Gurdon Institute, examined the transfer of RNA, an unstable molecule, through the jelly diet. They discovered that an abundant ingredient in jelly, Royal Jelly Protein-3 (MRJP-3), binds RNA to form granules that concentrate it and protect it from environmental damage. This is the first identification of RNA granules with functions outside cells and organisms.

Dr. Maori added, "Bees have developed a type of" glue "that binds RNA into granules, which makes it more stable and can be shared with other bees. If we can exploit this technology, we may be able to use it to develop new "vaccines" that can be used in agriculture, particularly to help immunize bees against the devastating losses of their colonies.

"It is possible that this bee protein also has applications for new vaccines and medicines for humans."