05 October 2010

Researchers combine smallpox, anthrax vaccines

Researchers have combined vaccines against smallpox and anthrax into one vaccine that could protect against both germs in a biological attack.

Researchers have combined vaccines against smallpox and anthrax into one vaccine that could protect against both germs in a biological attack.

The US government team said they had improved both vaccines, as well, to make them safer, faster-acting and more effective.

"Although licensed vaccines are available for both smallpox and anthrax, because of inadequacies associated with each of these vaccines, serious concerns remain as to the deployability of these vaccines, especially in the aftermath of a bioterror attack involving these pathogens," Liyanage Perera of the US National Cancer Institute and colleagues wrote.

Rapid delivery

The new dual vaccine can be freeze-dried, stockpiled and rapidly delivered when needed, they wrote in the Proceedings of the National Academy of Sciences.

Perera and colleagues at the US Food and Drug Administration and a small biotech company called JDM Technologies in Ellicott City, Maryland, had previously reported improvements to Wyeth's DryVax vaccine against smallpox. Wyeth now belongs to Pfizer Inc.

Smallpox was eradicated in 1979 after a sustained global vaccination campaign. But some experts say that the former Soviet Union had developed smallpox viruses into biological weapons and that they could have fallen into the hands of governments or extremist groups.

Anthrax occurs naturally but can also be developed into a deadly weapon.

In 2001, soon after the Sept. 11 attacks, five people died and more than a dozen others were injured when someone mailed letters laden with anthrax spores. A government anthrax researcher at Fort Detrick in Maryland was the chief suspect but he committed suicide before he could be charged.

Current vaccines

The current vaccine for smallpox has sometimes deadly side-effects. It is not used in the general population and people born after 1972 are very unlikely to have been vaccinated.

Emergent BioSolutions Inc's current anthrax vaccine does not work well and several companies are working on alternatives, some with multimillion-dollar US government contracts, including Emergent and PharmAthene Inc. Both vaccines are given to the US military.

Perera's team tweaked Wyeth's smallpox vaccine by adding an immune system compound called interleukin-15 or IL-15, and genetically altered the virus used to make it. They added one protein from the anthrax bacteria to make the dual vaccine.

Better protection

Tests in rabbits and mice suggested the combined vaccine would protect better than either of the older vaccines, they said.

"Our dual vaccine Wyeth/IL-15/PA remedies the inadequacies associated with the licensed vaccines," they wrote.

Antibiotics can protect people from anthrax but only if they are taken quickly. And the spores can live in the body for weeks and months before becoming active.

"We believe our dual vaccine, Wyeth/IL-15/PA, which is effective against two of the most deadly pathogens, will help consolidate and simplify our national bioterror counterefforts by streamlining the manufacture, stockpiling, and swift deployment of such vaccines should the need arise," the researchers concluded.

The vaccine would have to be approved by federal officials before it could be developed for use in people. The researchers were not immediately available to comment on when they would apply for approval. - (Maggie Fox/Reuters Health, October 2010)

SOURCE: Proceedings of the National Academy of Sciences, online October 4, 2010.


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