WASHINGTON — When traces of H5N1 bird flu showed up in cow’s milk last year, it raised fears that the virus could become more infectious to humans. So far, that hasn’t happened, virologist Richard Webby reported April 23 at the World Vaccine Congress Washington.
Cows were surprise hosts for the virus. Influenza viruses latch on to sialic acid attached to sugar molecules that decorate the outside of cells. It turns out that the way sialic acid is attached to some sugar molecules on cow mammary gland cells resembles attachments, or receptors, in birds. This arrangement allows the H5N1 virus to infect birds and cows, said Webby, of St. Jude