Although enveloped retroviruses bud from the cell surface of T lymphocytes, they use the
endocytic pathway and the internal membrane of multivesicular bodies for their assembly
and release from macrophages and dendritic cells (DCs). Exosomes, physiological
nanoparticles produced by hematopoietic cells, egress from this same pathway and are
similar to retroviruses in terms of size, density, the molecules they incorporate and their
ability to activate immune cells. Retroviruses are therefore likely to contaminate in vitro …