Extracellular vesicles are biological membrane objects having a size of less than 1000 nm, the main function of which is the transport of various biologically active molecules. They can also provide intercellular interactions and perform other biological functions. The review provides general information about extracellular vesicles, their varieties, morphological and microscopic features. The article gives various classifications of extracellular vesicles and considers pathogenetic features of the exosome interaction with viruses. Adding that the specific patterns of the introduction, interaction and identification of exosomes affected by viruses are determined on the example of a number of viruses. The possibility of extracellular vesicles to penetrate the blood-brain barrier, coordinating the immune system activity in response to the viral effects, is indicated. Exosome ability to mediate intercellular communication through innate and adaptive immune responses is discussed. The paper considers the prospects of using exosomes in the preventive diagnosis of infectious diseases, which will allow using exomes as the main diagnostic tool and determining the stage of infectious disease progression. The review provides information about the study of the exosome therapeutic possibilities. The authors have drawn conclusions about the importance of continuing the study of exosomes for use in the diagnosis and treatment of infectious diseases. KEYWORDS: viruses, extracellular vesicles, apoptotic bodies of exosomes, ectosomes, diagnosis, treatment. FOR CITATION: Ageykin A.V., Gorelov A.V., Usenko D.V., Melnikov V.L. Blood exosomes as new biomarkers of infectious diseases. Russian Medical Inquiry. 2021;5(11):744–748 (in Russ.). DOI: 10.32364/2587-6821-2021-5-11-744-748.