GAINESVILLE, Fla. -- Carbohydrates can be attractive, especially when they come packaged in candy bars or never-ending bowls of pasta.
Even viruses - those bits of occasionally harmful genetic material enclosed in shells of protein and fat - crave carbs. Except viruses aren't seeking a taste treat. They want to latch onto the carbohydrates that protrude from the surface of our cells and mount an invasion.
By changing which carbohydrates they attach to, viruses are able to infect cells more efficiently - a finding that may prove valuable to scientists seeking ways to fight cancer or brain diseases, say University of Florida researchers writing in the current Journal of Biological Chemistry. The discovery also helps explain how flu and other viruses are able to stay a step ahead of the body's own versatile immune system.
"If you think about the flu virus, a few simple amino acid changes can be the difference between a virus your body can defend against and one that will make you sick," said Mavis Agbandje-McKenna, Ph.D., an associate professor of biochemistry and molecular biology in the UF College of Medicine and senior author of the paper. "It seems structural juxtapositions of amino acids play a role in determining how viruses recognize cells and whether the viruses are harmful."
The idea that proteins on a virus' outer shell mutate to get a more lethal grip on a cell's sugary coat of carbohydrates, or glycans, became apparent when UF scientists studied the Minute Virus of Mice, or MVM.
One strain of the virus, MVMp, is harmless and causes no ill effects, even in mice without a functioning immune system. However, a different version of the virus, MVMi, can be fatal to these mice. Both viruses resemble miniature, 20-sided soccer balls, and between them their outer protein shells differ by only 14 out of more than 500 amino acids.