When it comes to vaccinating their babies, bees don't have a choice -- they naturally immunize their offspring against specific diseases found in their environments. 

In a honey bee colony, the queen rarely leaves the nest, so worker bees must bring food to her. Forager bees can pick up pathogens in the environment while gathering pollen and nectar. Back in the hive, worker bees use this same pollen to create "royal jelly" -- a food made just for the queen that incidentally contains bacteria from the outside environment.

After eating these bacteria, the pathogens are digested in the gut and transferred to the body cavity; there they are stored in the queen's 'fat body' -- an organ similar to a liver. Pieces of the bacteria are then bound to vitellogenin -- a protein -- and carried via blood to the developing eggs. Because of this, bee babies are 'vaccinated' and their immune systems better prepared to fight diseases found in their environment once they are born.

Vitellogenin is the carrier of these immune-priming signals, something researchers did not know until now.