Exosome isolation from hemolymph of Korean rhinoceros beetle, Allomyrina dichotoma (Coleoptera: Scarabaeidae)

Exosomes are 30 - 150 nm vesicles that are secreted from a range of cells. Recently, exosomes have been the subject of considerable research because there is mounting awareness of their diverse functions, including a role in cell - cell communication and presenting pathogens for immune responses. Exosomes contain diverse nucleic acid and protein cargos, derived not only from the organism but also from patho- gens, making them suitable for use in disease diagnosis. The Korean rhinoceros beetle, Allomyrina dichotoma (Coleoptera: Scarabaeidae), is commercially reared in Korea for the pet trade and is used in traditional medicine for liver-related diseases. However, several insect diseases caused by bacteria, fungi and viruses have been reported in A. dichotoma mass-rearing facilities. Identifying these dis- eases with accuracy and in a timely manner is of paramount importance. Such diagnosis can be accomplished by identifying the nucleic acid or amino acid fragments from these disease-causing pathogens in the exosome of A. dichotoma. We isolated exosomes from the hemolymph of A. dichotoma and used them to analyze exosome RNA and proteins. We confirmed the isolation of exosomes through RNA profiling, protein analysis and Western blotting. Our research estab- lished a solid foundation for using insect exosome protein and RNA analyses for the accurate diagnosis of insect diseases. To our knowledge, this is the first report of exosome isolation from insect hemolymph.