Deficiency Increases Severity of Flu Virus in Mice
By Judy McBride
April 27, 2001
If young mice are given a diet
deficient in selenium and subsequently exposed to a human influenza virus, they
get a more severe case of flu than animals fed adequate amounts of this
essential trace element.
Thats the finding of a collaborative study by researchers at the
University of North Carolina (UNC) in Chapel
Hill; Nestle Research Center in Lausanne, Switzerland; and the
Agricultural Research Service (ARS) in
Beltsville, Md. And it follows the pattern seen in earlier studies with a
lesser known virus. This indicates that a selenium deficiency can increase the
virulence of a variety of viruses.
The researchers reported today in the FASEB
Journal on the web that the mice getting selenium-deficient diets developed
significantly more lung pathology than the animals getting ample selenium. The
deficient mice had significantly more inflammation in their lungs, and the
inflammation lasted much longer.
Selenium is a critical part of a major antioxidant enzyme that humans and
animals produce to protect delicate cellular components against damage from
oxygen free radicals. Americans get ample selenium in their diets, according to
ARS nutritionist Orville A. Levander. Good sources include Brazil nuts, whole
grain products and meat. But deficiencies can occur in parts of China, New
Zealand and other nations where agricultural soils lack this element.
Levander collaborated with study leader Melinda A. Beck, a viral
immunologist at UNCs departments of Pediatrics and
Nutrition, on this and the earlier
studies. The researchers suspect that the influenza virus mutated to a more
virulent form in the selenium-deficient animals because these animals lack
antioxidant protection from the selenium-containing enzyme--glutathione
In 1995, the researchers reported that a normally harmless coxsackie virus
mutated into a heart-damaging pathogen in selenium-deficient mice, but not in
selenium- adequate mice. Beck and collaborators are now looking for mutations
in the influenza virus genome.
ARS is the U.S. Department of
Agricultures primary scientific research agency.
Scientific contact: Orville A. Levander, ARS
and Functions Laboratory, Beltsville, Md., phone (301) 504-8504, fax (301)