Some people may already have immunity to H1N1

New research by a UC Davis scientist and a UC Cooperative Extension specialist has found that some senior citizens already have a level of immunity to H1N1 flu, formerly known as Swine flu. The finding may explain why the 2009 H1N1-related symptoms have been generally mild, according to a UC Davis news release distributed to the media yesterday.

"The more you're exposed to viruses that can stimulate all types of immune response, the better protected you're likely to be," the Sacramento Bee quoted UCCE specialist and study co-author Carol Cardona in a story about the findings. "There does seem to be some level of antibody protection that people over 65 seem to have. There are some good things about getting older."

The scientists identified structural sites on the H1N1 virus that are also present in seasonal flu viruses that have been circulating for years. Many people over 60, who were likely exposed to similar viruses earlier in life from flu exposure or vaccinations, carry antibodies or another type of immunity against the new virus.

The study's authors, Cardona and project scientist Zheng Xing, are both associated with the UC Davis School of Veterinary Medicine. The news release says their study has implications for avian influenza.

About 80 percent of the epitopes - the structural sites on the virus - found in seasonal influenza and flu vaccine viruses are also present in the avian influenza virus. The scientists suggest that these epitopes may have protected some individuals infected with the avian flu virus through cytotoxic T-cell immunity.

Xing and Cardona's findings will appear in the November edition of Emerging Infectious Diseases, a journal published by the Centers for Disease Control and Prevention.

Drs. Xing and Cardona

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