Nature Medicine | Spoonful of Medicine

Broad-acting antibody brings researchers one step closer to a universal flu shot

flushot111111.jpgA universal flu vaccine is high on the wishlists of most immunologists, virologists — and even funding agencies. This week US National Institutes of Health director Francis Collins told USAToday that he’s “guardedly optimistic” that such a long-term shot will be developed within the next five years. That timeline could be aided by a report out today in Science that a single antibody is capable of inactivating all subtypes of influenza A.

A team led by Antonio Lanzavecchia, an immunologist at the Institute for Research in Biomedicine in Bellinzona, Switzerland, screened blood plasma from eight donors known to produce antibodies against multiple flu subtypes from a vaccination. One of these donors had H1N1 swine flu in 2009 and was vaccinated for seasonal flu in 2010 — and, in his plasma, the researchers discovered an antibody that appeared to target all 16 subtypes of influenza A. In animal studies, the antibody also protected mice from H1N1 swine flu and ferrets from H5N1 bird flu.

“This is a landmark study because the authors identified a single antibody that is capable of stopping virtually all different types of flu viruses,” immunologist Scott Hensley of Philadelphia’s Wistar Insitute told Nature Medicine.

Unlike <a href=“http://www.nature.com/nm/journal/v16/n12/full/nm1210-1347.html”’>previous approaches to developing a universal vaccine, which typically target proteins conserved across only a handful of the influenza A subtypes, this antibody binds to a region that “just can’t tolerate mutations,” Hensley says. Although other groups’ attempts to target this conserved region failed, this antibody works, preventing the virus from merging with the cell’s membrane to halt the infection’s spread.

It’s a major discovery — but don’t expect a universal vaccine tomorrow. The researchers still need to tailor an antigen that matches the antibody, develop a delivery system, and test it in humans. But this antibody does make Collins’s five-year timeline for a universal flu vaccine seem a bit more realistic.

Image: US Army Corp of Engineers Europe District, flickr under Creative Commons

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