科学美国人60秒:Senior Spit Has Anti-Flu Secret

Seasonal flu typically hits senior citizens harder than most other age groups. In fact, some 90 percent of flu-related deaths are estimated to occur in adults 65 and older. But with pandemic influenzas, like bird or swine flu, it's a different story.

Take the 2009 H1N1 flu. In that outbreak, adults over 65 actually suffered the fewest infections of any age group. That anomaly suggests they might have some sort of built-in immunity. Now researchers say the seniors' secret may be in their spit.

Researchers sampled saliva from 180 children, adult and elderly volunteers. Then they isolated proteins from the saliva, and tested how well the inhibitory proteins stuck to two strains of H9N2 bird flu.

Turns out elderly men and women had significantly more such proteins that interfere with the flu virus—which researchers say could boost the seniors' resistance to bird flu. Those results appear in the Journal of Proteome Research. [Yannan Qin et al., Age- and Sex-Associated Differences in the Glycopatterns of Human Salivary Glycoproteins and Their Roles against Influenza A Virus] 

The next step, researchers say, is to develop an oral or nasal spray based on these proteins. Which might give people of all ages a chance to send the flu a lethal loogie.

—Christopher Intagliata