Last year, when the H1N1 flu epidemic was a major public health concern, a relatively low proportion of individuals getting sick were elderly, compared to previous flu epidemics. To explain this, scientists hypothesized that flu strains that circulated decades ago were similar enough to the novel swine-origin H1N1 strain toÂ provide some immune protection.
Now, researchers at Emory’s Influenza Pathogenesis & Immunology Research Center have directly tested that hypothesis in mice, and it holds up. Exposure of mice to flu strains that circulated in 1947 or 1934 induced “robust cross-protective immune responses” and can protect them against a lethal challenge with 2009 H1N1 virus, they report in Journal of Immunology.
Ioanna Skountzou and Dimitrios Koutsananos are co-first authors of the paper.
The Emory team, led by Joshy Jacob, also reports that antibodies produced in response to the 2009 H1N1 flu strain exhibit broad cross-reactivity — they react with other H1N1 strains as well as against H3N2 flu strains. They write:
The fact that the 2009 H1N1 virus can induce such cross-reactive Abs raises the intriguing possibility that viruses such as A/California/04/2009 can be used for vaccines to induce broadly cross-reactive humoral immune responses against influenza viruses. Identifying the mechanism behind this broad reactivity may enable us to design broadly cross-reactive universal influenza vaccines.
National Institute of Allergy and Infectious Diseases director Tony Fauci, when he was at Emory for the H1N1 flu conference in April, discussed the idea of a universal flu vaccine: