In the case of human T-lymphotropic virus 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP), analysis of the exosomes isolated from patient cerebrospinal fluid showed the presence of transactivator protein Tax, proposing that HTLV-1 may release specific cargo for modulating its microenvironment [196]. This evidence concerns the gene CREB1 and tropical spastic paraparesis.