How flu virus spreads infection
Washington: Researchers have shown how influenza A viruses snip through a protective mucus net to infect respiratory cells and later cut their way out to infect other cells.
Principal investigator Pascal Gagneux, PhD, associate professor in the Department of Cellular and Molecular Medicine at UC San Diego, and his team could point the way to new drugs or therapies that more effectively inhibit viral activity, and perhaps prevent some flu infections altogether.
Scientists have long known that common strains of influenza specifically seek and exploit sialic acids, a class of signaling sugar molecules that cover the surfaces of all animal cells.
The ubiquitous H1N1 and H3N2 flu strains, for example, use the protein hemagglutinin (H) to bind to matching sialic acid receptors on the surface of a cell before penetrating it, and then use the enzyme neuraminidase (N) to cleave or split these sialic acids when viral particles are ready to exit and spread the infection.
Mucous membrane cells, such as those that line the internal airways of the lungs, nose and throat, defend themselves against such pathogens by secreting a mucus rich in sialic acids - a gooey trap intended to bog down viral particles before they can infect vulnerable cells.
Using a novel technique that presented viral particles with magnetic beads coated with different forms of mucin (the glycoproteins that comprise mucus) and varying known amounts of sialic acids, Gagneux and colleagues demonstrated that flu viruses counteract the natural barrier by also using neuraminidase to cut themselves free from binding mucosal sialic acids.
The findings have been published online in Virology Journal.