June 16, 2006 -- Scientists are working on an "ouch-free" vaccine against and anthrax.
The vaccine is still in experimental stages. So far, it's been tested on mice, not people.
Current tetanus vaccines are given by injection. The new version would go on the skin, without any needles, and might not require refrigeration -- a plus for storage and shipping.
So say Jianfeng Zhang, PhD, and colleagues in the journal Infection and Immunity. Zhang's team works in Birmingham, Ala. for the experimental vaccine's maker, Vaxin Inc.
Many more tests lie ahead.
In the journal, the researchers write that their latest finding may provide "the foundation for mitigating disease outbreaks and bioterrorist attacks in a simple, rapid, effective, economical, and painless manner."
The vaccine contains genetically engineered E. coli bacteria that are designed to be harmless. When applied to the skin, the vaccine is supposed to coax the body's immune system to defend against tetanus and anthrax.
The vaccine doesn't contain actual tetanus or anthrax bacteria. Instead, it includes DNA fragments of those bacteria to trigger an immune response without causing illness.
Zhang and colleagues tested the vaccine on young female mice. First, they shaved the mice and gently brushed their skin with a soft-bristle toothbrush. Next, they applied the vaccine to the skin.
An hour later, the scientists injected the mice with a lethal dose of a bacterium that causes tetanus. All of the vaccinated mice lived, but unvaccinated mice in a comparison group died within five days.
The researchers also tested the vaccine against anthrax, a substance used in bioterrorist attacks in the U.S. in 2001.
The results with anthrax exposure weren't as strong as those from the tetanus test.
After anthrax exposure, only 44% of the mice that got one dose of the skin vaccine survived. The survival rate increased to 55% for those exposed to anthrax after three monthly doses of the vaccine.
The genetically engineered bacteria didn't filter below the mice's skin, and its effects weren't permanent. Tests on mice showed a single dose of the vaccine lasted at least eight months, the researchers write.
Zhang's team sees other possible applications for their vaccine. They write that its design "may foster the development of a new generation of vaccines that can be manufactured rapidly and administered noninvasively in a wide variety of disease settings."