Exosomes are extracellular vesicles containing a variety of cell membrane molecules and related protein. They have been found to act as important intercellular messengers carrying functional RNAs, proteins and lipids that can induce phenotypic changes in recipient cells and promote cell activation or inhibition effect. In recent years, some studies have shown that exosomes can not only play an immune activation role to trigger antiviral immune response after viral infection, but also help to spread virus among cells, thus contributing to viral immune escape. Exosomes can either spread or limit an infection depending on the type of pathogen and the features of source cells, and can be studied as potential targets for development of antiviral drugs and vaccines. This review summarized the role of exosomes in viral infections with an emphasis on their potential contribution to pathogenesis.

Blood-brain barrier is a natural barrier between blood and brain tissue that can protect the brain from invasion by infectious pathogens in blood and maintain the homeostasis of the brain environment. However, neurotropic viruses can escape or disrupt blood-brain barrier and then invade the brain, causing serious complications in the central nervous system such as encephalitis and meningitis, which seriously threaten human life. This paper mainly summarized the research progress in the pathogenic mechanisms of common neurotropic viruses crossing blood-brain barrier and invading the central nervous system.