Nasally administered anthrax vaccine shows promise

Afraid of needles but still need that vaccine shot? Here is a new solution: A vaccine against anthrax which is more effective and easier to administer than the present vaccine. And yes: No need for needles. It has proven very effective in tests in mice and guinea pigs, according to a report by the University of Michigan Medical School scientists in the August issue of Infection and Immunity . The scientists were able to trigger a strong immune response by treating the inside of the animals’ noses with a “nanoemulsion” — a suspension of water, soybean oil, alcohol, and surfactant emulsified to create droplets of only 200 to 300 nanometers in size. It would take about 265 of the droplets lined up side by side to equal the width of a human hair. The oil particles are small enough to ferry a key anthrax protein inside the nasal membranes, in the process allowing immune-system cells to react to the protein and initiate a protective immune response. This process primes the immune system promptly to fight off infection when it encounters the whole microbe. The nanoemulsion anthrax vaccine does away with the need for needles, but it has another advantage: It is easy to store and use in places where refrigeration is not available.

An effective, easy-to-store, and easy-to-administer vaccine would be an important and useful tool for health authorities dealing with any future attack in which a terrorist might spread anthrax microbes. The researchers say a nasal nanoemulsion-based anthrax vaccine, if it proves effective in humans, could be given easily to people even after they are exposed in an anthrax attack, along with antibiotics. “Anthrax spores can remain in the environment or even in the lungs of exposed individuals for some time. Nasal vaccination could be given to build up immunity after anthrax exposure and improve the outcome of other treatments,” says Anna Bielinska, Ph.D., the paper’s lead author and a scientist at the Michigan Nanotechnology Institute for Medicine and Biological Sciences at the U-M. She is also an assistant research professor in the Allergy Division of Internal Medicine at the University of Michigan Medical School.

In the new study, the Wolverine team combined the nanoemulsion and a recombinant protein of Bacillus anthracis to make the vaccine, which they gave first to mice in either one or two applications. They found the animals developed several types of effective immune response. The vaccine produced both systemic and cellular immunity, meaning that the body produces antibodies and primes specific cells throughout the body to fend off anthrax infection. The vaccine also induced immunity on the mucous membranes of the nose and lungs, where inhaled anthrax spores enter the body and start a process that can cause illness and death. After administering the vaccine, the researchers challenged the immune systems of immunized guinea pigs with injections of 1,000 times the lethal dose of Bacillus anthracis spores. All the animals survived, whereas none of the control animals did. When the researchers delivered large doses of Bacillus anthracis spores directly into the animals’ nasal tissue, they found that 40 percent to 70 percent of the immunized animals survived.

Because of the biosafety restrictions on the use of anthrax, these challenge experiments were done at the Batelle Memorial Institute and the University of Texas Medical Branch, which have labs federally approved for handling the pathogen. The experiments so far have shown that the vaccine had no significant side effects and produced effective immunity for at least six months. The Michigan Nanotechnology Institute will seek funding to learn if the vaccine can produce immunity in primates as it does in rodents. Safety studies in humans are also in the early planning stage.

-read more in Anna U. Bielinska et al., “Mucosal Immunization with a Novel Nanoemulsion-Based Recombinant Anthrax Protective Antigen Vaccine Protects against Bacillus anthracis Spore Challenge,” Infection and Immunity 75, no. 8 (August 2007): 4020-29 (sub. req.)