For this study, researchers examined whether epitopes present in the seasonal flu strains between 1988 and 2008 also are found in the existing H1N1 strain. They used data catalogued in the Immune Epitope Database as well as information from the National Center for Biotechnology Information (NCBI) and the Global Initiative on Sharing Avian Influenza Data's (GISAID) influenza genetic sequence databases. Dr. Scheuermann said his team also analyzed the virus' genetic data using the NIH-sponsored Influenza Research Database (www.fludb.org), which he oversees at UT Southwestern.
The researchers found major genetic differences between the pandemic H1N1 strain and seasonal strains, potentially explaining why children and young adults are more susceptible to the H1N1 strain now circulating worldwide.
"Normally, older adults are generally more susceptible to pathogens like influenza, however, for the pandemic H1N1 strain this does not seem to be the case," said Dr. Scheuermann, who is also a member of the Cancer Immunobiology Center at UT Southwestern. "The antibody epitopes, which provide protection against disease, for the pandemic H1N1 strain are virtually all different from those present in recent seasonal strains, so young people have no built-in protective mechanisms. We speculate that older adults may have been exposed to viruses in their youth in which the epitopes are more similar."
At this point, he said, scientists must continue to be vigilant about tracking the pandemic H1N1 strain as it continues to evolve.
"H1N1 has not mutated in such a way as to make people sicker, but it could happen," Dr. Scheuermann said. "It is important that individuals follow the public health guidelines regarding vaccination as the H1N1 vaccine becomes more widely av
|Contact: Kristen Holland Shear|
UT Southwestern Medical Center