by Sanjay Mishra
Annual flu shots boost existing pools of immune cells that recognize closely related seasonal strains of the influenza virus. But there is no pre-existing immunity against emerging viruses, and that is what makes H5N1, the bird flu virus, such a concern.
Benjamin Spiller, Ph.D., James E. Crowe Jr., M.D., and colleagues have previously shown that human antibodies induced during testing of an experimental H5N1 vaccine can kill a laboratory-created strain of the virus.
Now, in a paper published in the Proceedings of the National Academy of Sciences, they describe how the most potent of these antibodies – H5.3 – “tricks” and neutralizes the virus: it poses as a type of sugar the virus needs to latch onto human cells.
They also report that H5.3 has a flexible and changeable structure like other still-maturing antibodies. These findings suggest that multiple exposures to diverse viral antigens, either through repeated immunizations or infections, may be the most effective way to generate robust immunity against uncommon viruses.
The research was reported in part by National Institutes of Health grants AI106002 and AI092268.
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