Previous seasonal flu infections may provide H1N1 immunity

Previous influenza infections may provide at least some level of immunity to the H1N1 “swine” flu, revealed by researchers at the La Jolla Institute for Allergy & Immunology, US.

“The question we asked was, “Is the swine flu more like the seasonal flu or like a totally new strain of influenza where there would be no immunity?,” said Alessandro Sette, Ph.D., an internationally recognized vaccine expert and director of the La Jolla Institute’s Center for Infectious Disease.

“What we have found is that the swine flu has similarities to the seasonal flu, which appear to provide some level of pre-existing immunity. This suggests that it could make the disease less severe in the general population than originally feared.”

The researchers used the Immune Epitope Database–a worldwide research tool developed and hosted by the La Jolla Institute and funded by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health–to conduct their study. Initially, the research team conducted their studies using computer modeling, and later used blood samples of adults representative of the normal population.

“We looked at the molecular markers for seasonal influenza viruses dating back 20 years and compared them with the molecular markers of the H1N1 influenza virus,” said Bjoern Peters, Ph.D., lead author on the study published in the Proceedings of the National Academy of Sciences. “We found that the immune system’s T cells can recognize a significant percent of the markers in swine flu.” T cells are infection-fighting white blood cells in the body’s immune system. “Nobody knows what level of immunity is sufficient for protection. We do know that a T cell response is not enough to prevent being infected by the virus. But, if infected, our data suggests that T cells in those who have previously been exposed to influenza may make the infection less severe,” Dr. Peters said.

The findings are based on knowledge that the body’s T cells recognize and will launch an attack against viruses — in this case certain molecular pieces of the swine flu — that they have seen before.

Source: La Jolla Institute for Allergy and Immunology, USA



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