WHAT: Mice injected with a 2009 H1N1 pandemic influenza vaccine and then exposed to high levels of the virus responsible for the 1918 influenza pandemic do not get sick or die, report scientists funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. The new vaccine works against the old virus because the 1918 and the 2009 strains of H1N1 influenza share features that allow vaccine-generated antibodies to recognize both viruses. To learn more, similar challenge studies need to be conducted in other animals, including monkeys, but the investigators say their results suggest people who are vaccinated against 2009 H1N1 influenza or were exposed to the virus could have similarly cross-protective antibodies against the 1918 strain of H1N1. This finding, they add, should help allay concerns about the potential consequences of an accidental release of the 1918 influenza virus from high-containment laboratories or its possible use as a bioterror weapon.
Adolfo Garcia-Sastre, Ph.D., of Mount Sinai School of Medicine, New York, led the research. Groups of mice were exposed to lethal amounts of the 1918 influenza virus 14 or 28 days after receiving a 2009 H1N1 influenza vaccine; a seasonal H3N2 influenza vaccine (not designed to protect against H1N1 virus); or no vaccine. All of the 2009-H1N1-vaccinated mice survived. Unvaccinated mice and mice that received the H3N2 vaccine all died. (A group of mice vaccinated with a seasonal flu vaccine designed to protect against a 2007 strain of H1N1 were mostly protected from lethal challenge; 80 percent of the mice in that group survived.)
The researchers also injected mice with blood serum taken from people who had received 2009 H1N1 influenza vaccine. The serum, which contained antibodies against 2009 H1N1 influenza virus, protected the mice from death when they were later exposed to the 1918 H1N1 influenza virus. All the experiments involving the 1918 virus were conducted under biosafety-level-3 conditions.
|Contact: Anne A. Oplinger|
NIH/National Institute of Allergy and Infectious Diseases