Safer smallpox vaccine under development

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.