June 1, 2009 (Vol. 29, No. 11)
Using a method he developed for the H5N1 bird flu, Purdue University researcher Suresh Mittal, D.V.M., Ph.D., believes he will be able to create a vaccine that will work against the 2009 H1N1 flu strain and its variants.
Dr. Mittal, a professor of comparative pathobiology in the school of veterinary medicine, received gene samples of the new H1N1 virus (swine flu) early last month. With scientists at the Centers for Disease Control and Prevention, Dr. Mittal hopes to have a vaccine ready for testing within the month.
“We would like to have a vaccine in two to three weeks to start testing in mice,” says Dr. Mittal. “We are trying to use a similar approach with the 2009 H1N1 virus as we did with the H5N1 bird flu virus.”
Traditional flu vaccines are composed of virus components from three flu viruses grown in chicken eggs. Since the flu viruses used are dead, instead of causing illness they create an antibody-based protection against closely related flu strains. This occurs because immune cells at the site of the injection take up flu proteins called antigens.
Those traditional vaccines will not protect against the 2009 H1N1 influenza, however. The influenza virus is constantly changing, which is why seasonal flu vaccines need to be tailored each year to better match strains expected to affect people during the flu season.
Gene Delivery via Adenovirus
Dr. Mittal and CDC collaborators used an adenovirus to carry a gene of the H5N1 bird flu virus in 2006. “The adenovirus is incapable of replicating and does not seem to cause disease in humans,” Dr. Mittal said. “That makes it a suitable virus to work with for flu vaccines.”
When the virus enters cells in a person’s body, the cells use the influenza genes to create the antigens themselves. By doing so, the cells create both antibodies and cell-based protection from mutated forms of the influenza virus.
The vaccine Dr. Mittal created for the bird flu worked on three different strains isolated over a seven-year period. He’s hoping to see similar success with a 2009 H1N1 flu vaccine.
Now that work has begun, Dr. Mittal believes a 2009 H1N1 vaccine using the adenovirus could be ready for production in a few months.