Recent Advances in the Development of an Improved, Human Anthrax Vaccine

Human anthrax vaccines currently licensed in the United States and Western Europe consist of alum-precipitated or aluminum hydroxide-absorbed supernatant material from fermentor cultures of toxigenic, nonencapsulated strains of Bacillus anthracis. These vaccines have several drawbacks, including the need for frequent boosters, the apparent inability ot protect adequately against certain strains of B. anthracis, and occasional local reactogenicity. Studies are being undertaken to develop an improved human anthrax vaccine which is safe and efficacious, and which provides long-lasting immunity. Aspects being studied include the identification of antigens and epitopes responsible for eliciting protective immunity, the mechanisms of resistance to anthrax infection, the role of specific antibody in resistance, the differences in immunity elicited by living and chemical vaccines, the potential of new adjuvants to augment immunity, and the feasibility of developing safe vaccine strains having mutationally altered toxin genes. Both living and non-living chemical prototype vaccines are being developed and tested.