Sacbrood virus of the larval honey bee (Apis mellifera linnaeus)

Extracts of honey bee larvae suffering from sacbrood contained many isometric particles that were about 28 mμ in diameter. When the extracts or purified preparations of the particles were put into the food of healthy larvae, these developed sacbrood. The particles, which were not found in comparable extracts of healthy larvae, resemble those of acute bee paralysis virus, but cross infection and serological tests failed to show any relationship between the two viruses. Isolates of sacbrood virus from Europe and North America appear to be identical.