April 19 - Recent in vitro tests show that an extract from an ancient mushroom -- Fomitopsis officinalis -- could be an antidote to "weaponized" viruses such as pox, according to Fungi Perfecti, a research lab in Kamilche Point, Wash.

F. officinalis is a wood conk mushroom known for thousands of years as Agarikon. Nearly extinct, the mushroom is still found in the old-growth forests of the American Pacific Northwest.

For the past two years, Paul Stamets, owner and director of Fungi Perfecti, has prepared more than 100 strains of medicinal mushroom extracts for testing by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), and the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), in their joint biodefense antiviral screening program.

The NIH/USAMRIID screening program tests the mushroom extracts against viruses that could be weaponized, including the viruses causing yellow fever, dengue, SARS and pox. Of the Agarikon samples submitted, several showed "potent activity" for reducing infection from vaccinia and cowpox, which are in the same family as the smallpox virus, Stamets said.

"Several of Stamets' medicinal mushroom extracts have shown very interesting activity against pox viruses in cell culture assays performed through NIAID, and we are hopeful that they will also prove effective in the animal model systems," said Dr. John A. Secrist III, vice president of Southern Research Institute's Drug Discovery Division, who oversees an NIAID contract to evaluate potential antiviral drugs. "The number of different classes of compounds that show promising activity is small, so finding something new would be of great benefit to the scientific community."

Stamets has filed several patents, both U.S. and international, on the antiviral properties of mushrooms in the Fomitopsis family. However, according to Stamets, only compounds derived using his proprietary, patent-pending methodology for cell cultures show activity; simple extracts from the woody conks (such as tea or infusions) are not active.

Harvesting these rare conks from the forests will not provide therapeutic benefits and could impair the reproduction of the fungus, Stamets cautioned.

"The ecological niche for these unique mushrooms is increasingly jeopardized as humans destroy old-growth habitats," Stamets said. "As this happens, the pool of available strains will be further reduced. Acquiring as many strains as possible should be an international priority so that preventive or curative medicines against pox and related viruses can be developed. Personally, I believe we should be saving our old-growth forests as a matter of national defense."