Good Nutrition Could Help Prevent Bad Viruses

Once again, a relatively benign virus has mutated into a nasty pathogen in laboratory mice that were raised on a diet deficient in selenium, a potent antioxidant. This time the mutations occurred in a common influenza virus, a strain isolated in Bangkok in 1979.

And the mutations persisted in mice fed ample selenium, causing a much more severe case of flu than the original strain. A report on the study, by researchers with the University of North Carolina, the Nestle Research Center in Switzerland and the Agricultural Research Service, will appear online in The FASEB Journal Express.

The discovery, according to the researchers, demonstrates a unique mechanism by which viruses can mutate and points to the importance of antioxidant protection against viral diseases. The selenium level in the study’s deficient diet was one-sixtieth that of the adequate diet.

Seven years ago, UNC virologist Melinda A. Beck and ARS nutritionist Orville Levander reported that a lesser known virus--a strain of coxsackie--mutated from “Jekyll” to “Hyde” in selenium-deficient mice. This April, the two researchers and their colleagues reported that the Bangkok strain of influenza virus also caused a much more severe case of flu in selenium-deficient mice than in animals given adequate selenium in their feed. In the new report, they explain why.

Twenty-nine bases in a normally stable section of the viral genome had mutated in the selenium-deficient mice. By contrast, there were no mutations in the same area of the viral genome from selenium-adequate mice. It shows that the host’s nutrition can have considerable influence on the virulence of viral pathogens and that the virulence persists in well-nourished animals and, presumably, people.

The findings have global implications, according to Levander, who is at the Beltsville (Md.) Human Nutrition Research Center. While Americans generally get the recommended dietary levels of selenium, there are pockets of selenium deficiency around the world that might be generating harmful mutations in a number of viruses. And viruses know no boundaries.

ARS is the U.S. Department of Agriculture’s chief scientific research agency.

Scientific contacts: Orville A. Levander, ARS Nutrient Requirements and Functions Laboratory, Beltsville, Md., phone (301) 504-8504, fax (301) 504-9062, [email protected]. Melinda A. Beck, University of North Carolina, Departments of Nutrition and Pediatrics, Chapel Hill, N.C., phone (919) 966-6809, fax (919) 966-0135, [email protected].