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13 years ago
Early success for universal flu vaccine There are signs that one bid to create a universal flu vaccine that would provide protection against all strains of flu is working. And this one might pack some extra evolutionary aces up its sleeve.
The flu vaccines humanity now has at its disposal work only against a few kinds of flu, for a short time. Ordinary seasonal flu continually evolves and changes its surface proteins, so it can get round our immunity to last year's virus, and last year's vaccine. Therefore we constantly need to update flu vaccines and be re-vaccinated to keep from getting flu.
This is more than just a nuisance. Producing vaccine tailor-made for each new flu virus is such a long, clumsy process that when a really novel virus emerges unexpectedly and goes pandemic, it can kill without a hindrance for months before a vaccine is ready.
We didn't have significant quantities of vaccine against the 2009 swine flu until after the first, and nearly all of the second, waves were already over in the Americas.
To overcome this problem, several research groups are trying to make a flu vaccine out of proteins that are the same in all flu viruses, but to which people don't normally mount much of an immune response, in the hope that this will protect us from all flu once and for all.
Many are based on specific proteins of flu, called M and NP. As we reported in 2009, one of these groups, from Oxford University, are doing this using a live, innocuous strain of Vaccinia virus, which used to be used to vaccinate against smallpox.
This Ankara strain, or MVA, is especially safe and has been tested in children and the HIV-positive. Gilbert and colleagues tacked M and NP onto an MVA virus and injected it into 28 healthy adult volunteers. They report that it was safe - and had an astonishing effect on the volunteers' immune systems.
Most vaccines aim to induce antibodies, which rapidly recognise pathogens and prevent infection. MVA instead mobilises large numbers of white blood cells called T-cells. T-cells remember various bits of the germs they've seen. Virtually everyone carries a few T-cells that recognise the M and NP proteins. These cells normally help fight off flu, but aren't quick or numerous enough to prevent infection or reliably limit disease.
The Oxford vaccine stimulated huge numbers of T-cells - in fact, more than the researchers have ever seen with other experimental vaccines based on MVA and aimed at malaria, HIV and TB.
Mark Fielder, a medical microbiologist at Kingston University, told UK newspaper the Daily Mail:
"The findings are extremely encouraging in terms of the apparent efficacy of the virus and the fact that it appears to be a safe formulation. However, I think that a larger trial will be able to confirm these findings and let this technology be taken forward."
The group now wants to see if this really protects people from flu, using an enclosed lab in London where volunteers can be deliberately exposed to flu virus.
If it works, it might have an unusual evolutionary twist. Vaccines that prevent any infection at all put enormous pressure on the pathogen to evolve and evade the vaccine, as the germ cannot live otherwise - that seems to have happened with whooping cough bacteria.
But a vaccine that lets a pathogen infect, but limits its severity, might be something the pathogen is not under such pressure to evade. A vaccine that mainly works through T-cells might allow the flu to pass through us every year, possibly causing little more than sniffles, but each time acting as a live booster vaccine, keeping our antibodies and other immunity to flu up to date. It's a tantalising thought.
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