H5N1 bird flu viruses have acquired a molecular trick that makes them more easily infect mammary glands in cattle, but this adaptation does not appear to affect humans.
To infect cells, influenza viruses latch on to certain sugars decorating cell surfaces. Some H5N1 viruses have picked up mutations that allow them to grab one such sugar made by cattle but not by humans or birds, researchers report April 6 at bioRxiv.org.
Specifically, two mutations commonly found in H5N1 viruses infecting dairy cattle now allow the bird flu viruses to grip the sugar N-glycolylneuraminic acid, or NeuGc. Grasping this cattle sugar made it easier for H5N1 bird flu viruses to