DALLAS Nov. 16, 2009 As the number of deaths related to the pandemic H1N1 virus, commonly known as "swine flu," continues to rise, researchers have been scrambling to decipher its inner workings and explain why the incidence is lower than expected in older adults.
In a study appearing online and in a future issue of Proceedings of the National Academy of Sciences, a UT Southwestern Medical Center researcher and his collaborators in California show that the molecular makeup of the current H1N1 flu strain is strikingly different from previous H1N1 strains as well as the normal seasonal flu, especially in structural parts of the virus normally recognized by the immune system.
Prior research has shown that an individual's immune system is triggered to fight off pathogens such as influenza when specific components of the immune system namely antibodies, B-cells and T cells recognize parts of a virus known as epitopes. An individual's ability to recognize those epitopes spurred by past infections or vaccinations helps prevent future infections. The challenge is that these epitopes vary among flu strains.
"We hypothesize that older people are somewhat protected because the epitopes present in flu strains before 1957 may be similar to those found in the current H1N1 strain, or at least similar enough that the immune system of the previously infected person recognizes the pathogen and knows to attack," said Dr. Richard Scheuermann, professor of pathology and clinical sciences at UT Southwestern and a co-author of the paper. "Those born more recently have virtually no pre-existing immunity to this pandemic H1N1 strain because they have never been exposed to anything like it."
Between April and mid-October, the current H1N1 virus sickened roughly 22 million Americans and contributed to or caused about 4,000 deaths, according to the figures recently released by the Centers for Disease Control and Prevention. The deat
|Contact: Kristen Holland Shear|
UT Southwestern Medical Center