Researcher Yasuhiro Tsukamoto's flock of 500 ostriches is being enlisted into the global fight against swine flu by exploiting Japan's practice of wearing masks in public to ward off allergies and colds.

Tsukamoto, 40, a veterinary professor at Kyoto Prefectural University, was part of a team that investigated the deaths of birds in 2004 when avian influenza hit farms in western Japan. The probe into the virus that killed three-fifths of infected people worldwide spurred him to produce flu-fighting antibodies from ostriches, which are resistant to infectious diseases.

In July, even before the new H1N1 outbreak surfaced, Tsukamoto began selling, for about ¥190 each, face masks lined with the ostrich antibodies. The new flu circling the globe has heightened the nation's obsession with wearing face masks, leading shops to sell out plain white surgical types as well as patterned varieties, even those with Mickey Mouse themes.