The team tested whether three of their cross-reactive antibodies could protect mice against the 2009 strain or two other common lab strains. Two antibodies protected mice against an otherwise lethal dose of any of the three strains, even when the antibody was given 60 hours after infection.
One antibody, from the patient with the most severe illness, only protected against the 2009 H1N1 strain. The antibody genes from that patient suggest that the patient had a complete lack of preexisting immunity to H1N1 viruses. In cases where patients experienced a milder illness, it appears that immune cells that developed in response to previous seasonal flu shots or infections formed a foundation of response to 2009 H1N1 strain.
Although relatively few patients could be analyzed in detail at the antibody level, the authors conclude that "with the proper immunogen, the long-sought development of a pan-influenza vaccine might be possible."
Next, the research team is planning to examine the immune responses of people who were vaccinated against the 2009 H1N1 strain but did not get sick to see if they also produce antibodies that protect against many influenza strains.
|Contact: John Easton|
University of Chicago Medical Center