Doubling up against anthrax

Anthrax infections can rapidly progress from nonspecific initial symptoms to death. This is caused by a dual process of bacterial replication and toxin production, but the only human vaccine currently available is directed at only the toxins and does not target bacilli multiplication. In the September 2 PNAS, Gi-Eun Rhie and colleagues at Harvard Medical School describe a dually active anthrax vaccine (DAAV) that confers simultaneous protection against both bacilli and toxins (PNAS, DOI:cgi/doi/10.1073/pnas.1834478100, September 2, 2003).

Rhie et al. created a DAAV vaccine by conjugating the capsular poly-γ-D-glutamic acid (PGA) to protective antigen (PA). This converted the weakly immunogenic PGA to a potent immunogen and synergistically enhanced the humoral response to PA. The authors observed that PGA-specific antibodies bound to encapsulated bacilli and promoted the complement-mediated killing of bacilli. In addition, PA-specific antibodies neutralized toxin activity and protected against lethal challenges with anthrax toxin.

"We envision that our DAAVs ...