This article is getting the "cure for the common cold" push in a number of newspaper headlines and blog posts. I'm always alert for those, because, as a medicinal chemist, I can tell you that finding a c-for-the-c-c is actually very hard. So how does this one look?
I'd say that this falls into the "interesting discovery, confused reporting" category, which is a broad one. The Cambridge team whose work is getting all the press has actually found something that's very much worth knowing: that antibodies actually work inside human cells. Turns out that when antibody-tagged viral particles are taken up into cells, they mark the viruses for destruction in the proteosome, an organelle that's been accurately compared to an industrial crushing machine at a recycling center. No one knew this up until now - the thought had been that once a virus succeeds in entering the cell, that the game was pretty much up. But now we know that there is a last line of defense.
Some of the press coverage makes it sound as if this is some new process, a trick that cells have now been taught to perform. But the point is that they've been doing it all along (at least to nonenveloped viruses with antibodies on them), and that we've just now caught on. Unfortunately, that means that all our viral epidemics take place in the face of this mechanism (although they'd presumably be even worse without it). So where does this "cure for the common cold" stuff come in?
That looks like confusion over the mechanism to me. Let's go to the real paper, which is open-access in PNAS. The key protein in this process has been identified as tripartite-motif 21 (TRIM21), which recognized immunoglobin G and binds (extremely tightly, sub-nanomolar) to antibodies. This same group identified this protein a few years ago, and found that it's highly conserved across many species, and binds an antibody region that never changes - strong clues that it's up to something important.
Another region of TRIM21 suggested what that might be. It has a domain that's associated with ubiquitin ligase activity, and tagging something inside the cell with ubiquitin is like slapping a waste-disposal tag on it. Ubiquinated proteins tend to either get consumed where they stand or dragged off to the proteosome. And sure enough, a compound that's known to inhibit the action of the proteosome also wiped out the TRIM21-based activity. A number of other tests (for levels of ubiquitination, localization within the cell, and so on) all point in the same direction, so this looks pretty solid.
But how do you turn this into a therapy, then? The newspaper articles have suggested it as a nasal spray, which raises some interesting questions. (Giving it orally is a nonstarter, I'd think: with rare exceptions, we tend to just digest every protein that gets into the gut, so all a TRIM21 pill would do is provide you with a tiny (and expensive) protein supplement). Remember, this is an intracellular mechanism; there's presumably not much of a role for TRIM21 outside the cell. Would a virus/antibody/TRIM21 complex even get inside the cell to be degraded? On the other hand, if that kept the virus from even entering the cell, that would be an effective therapy all its own, albeit through a different mechanism than ever intended.
But hold on: there must be some reason why this mechanism doesn't always work perfectly - otherwise, no nonenveloped virus would have much of a chance. My guess is that the TRIM21 pathway is pretty efficient, but that enough viral particles miss getting labeled by antibodies to keep it from always triggering. If that's true, then TRIM21 isn't the limiting factor here - it's antibody response. If that's true, then it could be tough to rev up this pathway.
Still, these are early days. I'm very happy to see this work, because it shows us (again) how much we don't know about some very important cellular processes. Until this week, no one ever realized that there was such a thing as an intracellular antibody response. What else don't we know?