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Safer smallpox vaccine under development

Posted on: Tuesday, 24 January 2006, 10:24 CST

WASHINGTON (Reuters) - Chimpanzee blood may be used to provide a safer vaccine against smallpox, U.S. researchers reported on Monday.

A vaccine made by splicing chimp and human antibodies was both safer and more effective than the current vaccine, which uses a live virus and has a high rate of side effects, researchers reported.

"This is an important finding in the race to develop effective measures against a potential bioterror attack involving the deadly smallpox virus," said Dr. Elias Zerhouni, director of the National Institutes of Health.

"It is imperative that we have effective treatments available that everyone could use in the event of a bioterror attack," added Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, where the study was done.

"This study shows that there are potential alternatives to existing treatments and perhaps to existing vaccines that we can use to enhance our arsenal of medical countermeasures."

Smallpox was eradicated as a naturally occurring infection in 1980, but experts fear that some samples of the virus were made into biological weapons that groups or governments could use in an attack.

So the U.S. government has been vaccinating military personnel and some police, health and emergency workers against smallpox, using Wyeth's old DryVax vaccine. This vaccine is based on decades-old technology and uses the vaccinia virus, which is related to smallpox.

It can cause severe side effects and, rarely, death.

The NIAID's Dr. Robert Purcell and colleagues made a synthetic antibody -- an immune system protein that recognizes and helps neutralize invaders such as viruses.

They genetically engineered parts of an antibody from chimpanzees, which are immune to smallpox, and a human antibody.

Tests in mice showed it prevented infection with vaccinia. In the lab, it neutralized samples of the actual smallpox virus.

The vaccine might help avoid complications from the smallpox vaccine and might even directly protect people from smallpox, the researchers report in this week's issue of the Proceedings of the National Academy of Sciences.

Two companies are working on a more advanced smallpox vaccine for the U.S. government -- Danish vaccine maker Bavarian Nordic and British vaccine maker Acambis Plc.

Source: REUTERS

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