Public healthA new dual vaccine protects against both smallpox and anthrax

Scientists have developed and tested a new protective vaccine against smallpox and anthrax, two agents of bioterrorism, in animal models. Liyanage P. Perera, Ph.D., NCI, and colleagues made the enhanced dual vaccine by inserting the genes for protective parts of anthrax and the immune-boosting chemical, interleukin-15, into the backbone of the licensed smallpox vaccine, ACAM2000.

They found their new vaccine more quickly elicited immunity and was more effective than the licensed anthrax vaccine, BioThrax, in protecting mice and rabbits against anthrax — it was also safer in immune deficient mice and more effective than the licensed smallpox vaccine in protecting mice and monkeys. The study appeared online in PNAS on 4 October 2010.

Current licensed vaccines for smallpox and anthrax have certain negative side effects, require multiple doses, or have certain storage and delivery problems. For example, ACAM2000 may cause encephalitis, cardiac inflammation, and is also contraindicated for people with weakened immune systems or those with eczema; BioThrax has a short shelf-life and requires multiple boosters to confer adequate protection. Added to the benefit of having one vaccine that effectively protects against two deadly pathogens this new vaccine can be freeze-dried, stockpiled, and rapidly delivered in the event of a bioterror attack involving smallpox or anthrax. Plans are underway for further safety and efficacy testing of this new vaccine in non-human primates with the view of advancing this vaccine for testing in humans.

—Read more in Tod J. Merkel et al., “Development of a highly efficacious vaccinia-based dual vaccine against smallpox and anthrax, two important bioterror entities,” Proceedings of the National Academy of Sciences, 4 October 2010 (doi:10.1073/pnas.1013083107) (sub. req.)