Exosomes-mediated transmission of foot-and-mouth disease virus in vivo and in vitro.

Exosomes are small membrane-enclosed vesicles that participate in intercellular communication between cells. Numerous evidences suggested that exosomes derived from virus-infected cells can mediate virus transmission or/and regulate immune response. Foot-and-mouth disease virus (FMDV) is the prototype member of the Aphthovirus genus of the Picornaviridae family. It can cause highly infectious disease of cloven-hoofed livestock and significantly increase public awareness. However, the role of exosomes in the transmission of FMDV has still remained unknown. In this study, full length of FMDV genomic RNA and partial viral proteins were identified in purified exosomes isolated from FMDV-infected PK-15 cells with qRT-PCR and /MS. Exosomes from FMDV-infected cells were capable of transmitting infection to naive PK-15 cells and suckling mice. Furthermore, exosome-mediated infection cannot be fully blocked by FMDV-specific neutralizing antibodies. This finding highlights that FMDV transmission by exosomes as a potential immune evasion mechanism.