A number of retroviruses, including HIV, induce cells to form long bridges along which the virus particles move from infected cells to uninfected cells, according to a paper in the March 2007 issue of Nature Cell Biology.
Viral transmission has long been recognized to be more efficient between infected and target cells that are in direct contact with each other. Exactly how viruses move from one cell to another is unclear, although structures called virological synapses, which contain the virus particle and form between areas of cell-cell contact, are thought to be important in this process.
In the present study Walther Mothes and colleagues describe a novel mode of cell-cell transmission for three retroviruses -- murine leukaemic virus, human immunodeficiency virus and avian leucosis virus -- along the outside of long, thin intercellular bridges. These bridges seem to be stabilized by an association between a viral protein expressed by the infected cell and a viral-receptor protein in the target cell. Mutants of these proteins that cannot interact destabilize the bridges and markedly reduce viral spreading from cell to cell. This mode of transmission is observed in a variety of different cells, suggesting that it may be a general mechanism of viral spreading.
Whether these intercellular viral highways represent a predominant mode of viral transmission, their relative importance for different viruses, and their relationship to virological synapses are open questions. However, interference with the bridge structures described by Mothes and colleagues may provide a new avenue to limit the infectivity of a number of key viral diseases.
Walter Mothes (Yale School of Medicine, New Haven, CT, USA)
Abstract available online.
(C) Nature Cell Biology press release.
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