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No safe haven for viruses: How infected cells can hold the line


This neat, short video (linked to article in The Guardian) depicts a breakthrough in immunology: a hitherto-unsuspected method by which virus-infected cells fight back - at least some of the time.

Viruses multiply by hijacking the DNA-replicating machinery of the cells they infect. Bloodborne pathogen-targeting proteins called antibodies constitute an early line of immune defense. By affixing themselves to a viral particle's surface after it has gained entry to the bloodstream but before it has broken into a cell, antibodies tag the virus for demolition by attack squadrons consisting of aggressive immune cells.

It has long been thought that, once inside the safe haven of a cell, a virus can be defeated only by destroying the infected cell. And sure enough, our immune system boasts several sets of white blood cells that are equipped to do just that. But it's a little extreme - all the more so when the cell in question is relatively indispensable because it's seldom replaced by like cells (for instance, in the heart) or structurally unique (such as a nerve cell, with all its customized connections to other nerve cells).

It turns out that, if antibodies manage to bind to a viral particle in the bloodstream, they can ride it piggyback-style all the way into a cell's interior. Breaking research now indicates that, should such an antibody-tagged virus penetrate a cell, specialized roving molecules inside the cell can recognize and grab onto its antibody accoutrements. That causes mobile garbage disposals known as proteasomes to swoop down, sirens a-blazing, and chew the invader to smithereens. (Sounds like a game that someone rooting for the home team may rather win than watch.)

Clearly, our cellular home-alarm system isn't foolproof, or we'd never get viral diseases. But the researchers showed that boosting intracellular supplies of the antibody-recognizing molecule made cells more effective at destroying invading viruses, suggesting possible brand-new therapeutic approaches to infection.

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