XMRV DOES NOT NEED TO ENTER THE BLOOD AT ALL TO SPREAD THROUGH THE BODY.IN FACT ENTERING THE BLOOD SLOWS IT DOWN.THE VIRUS IN THE PAPER IS A MLV Nature Cell Biology 9, 310 - 315 (2007) Published online: 11 February 2007 | doi:10.1038/ncb1544 * Article Links o Supplementary info o See Also + News and Views by Hope * Article Tools o Send to a friend o Export citation o Export references o Rights and permissions o Order commercial reprints o Bookmark in Connotea * Search Pubmed for o Nathan M. Sherer o Maik J. Lehmann o Luisa F. Jimenez-Soto o Christina Horensavitz o Marc Pypaert o Walther Mothes o more authors of this article Retroviruses can establish filopodial bridges for efficient cell-to-cell transmission Nathan M. Sherer1,3, Maik J. Lehmann1,4, Luisa F. Jimenez-Soto1,5, Christina Horensavitz2, Marc Pypaert2 & Walther Mothes1 Abstract The spread of retroviruses between cells is estimated to be 23 orders of magnitude more efficient when cells can physically interact with each other1, 2. The underlying mechanism is largely unknown, but transfer is believed to occur through large-surface interfaces, called virological or infectious synapses3, 4, 5, 6. Here, we report the direct visualization of cell-to-cell transmission of retroviruses in living cells. Our results reveal a mechanism of virus transport from infected to non-infected cells, involving thin filopodial bridges. These filopodia originate from non-infected cells and interact, through their tips, with infected cells. A strong association of the viral envelope glycoprotein (Env) in an infected cell with the receptor molecules in a target cell generates a stable bridge. Viruses then move along the outer surface of the filopodial bridge toward the target cell. Our data suggest that retroviruses spread by exploiting an inherent ability of filopodia to transport ligands from cell to cell.