The flu vaccine: a tedious annual chore, but necessary unless you want to spend a week bed-ridden and barfy. Still, wouldn't it be great if one jab could protect you for life? A lifetime flu vaccine isn't impossible, and we're making progress toward one, but we've still got a ways to go.
As New Scientist explains, the flu virus carries big, globular "decoy" proteins on its surface to grab our immune system's attention. It's these decoys that we put in our vaccines to prime our immune systems for the flu. But true to their name, decoy proteins are shapeshifting little bastards, and after a couple years, our immune systems don't recognise them anymore. That's why we spend hundreds of millions of dollars predicting what the next flu outbreak will look like and developing new vaccines in advance of it.
Beneath the decoys, however, lie the "stalk" proteins involved in replicating the virus and infecting us. These proteins happen to be much more structurally stable. If we could somehow convince our immune systems to recognise them, our bodies wouldn't "forget" the flu from year to year. But according to New Scientist, stalk proteins have proven devilishly hard to reproduce in the lab.
After years of tinkering, two research groups announced this week that they have manufactured stable versions of an H1N1 stalk protein in an injectable solution. But so far, both vaccines have met mixed results in animal trials. Says New Scientist:
One group, at the Crucell Vaccine Institute in Leiden, the Netherlands, and the Scripps Research Institute in La Jolla, California, succeeded in making an array of three of these stalk proteins that matches the kind that forms naturally in the virus. It protected mice from otherwise lethal doses of the H1N1 flu — and from the very different H5N1 bird flu. Less promisingly, however, in monkeys the vaccine only reduced the fever caused by low, non-lethal doses of H1N1 viruses, even though vaccinated monkeys produced antibodies to several flu types.
The other group, based at the National Institutes of Health, tied several stalk proteins together with a bacterial protein into a spiky protein bundle, and stuck that in solution. This version also elicited an immune response, but it wasn't powerful enough to prevent infection:
Sure enough, this elicited antibodies that recognised the stalk proteins in viruses from the H1, H2, H5 and H9 families, and even against the less similar H3 and H7. Once again, though, antibodies were one thing, surviving a real infection was another. All the vaccinated mice survived an otherwise lethal dose of H5N1 flu, but only four of six ferrets did — and ferrets' response to flu is thought to be a much better model for the human response to the virus.
The silver bullet here would be a flu protein that doesn't change over time, that we can deliver as a vaccine, and that will fire up our immune systems enough to prevent us from catching the flu in the first place. So far, we seem be hitting the first two criteria, but the vaccine — in animals, at least — remains too weak to prevent illness.
Experts in the field, however, say the recent progress is very promising, and that a future of universal flu vaccines may be on the horizon. "This is a leap forward compared to anything done recently," flu expert Jon Oxford of the University of London told the BBC. "They have good animal data, not just in mice but in ferrets and monkeys too. And they have done it with the bird flu virus H5N1. It's a very good stepping stone."
Meanwhile, do us all a favour and keep getting your damn flu vaccine.