Scientific Publications by FDA Staff

Hum Vaccin Immunother 2013 Sep 1;9(9):1841-8

Protective-antigen (PA) based anthrax vaccines confer protection against inhalation anthrax by precluding the establishment of a systemic infection.

Merkel TJ, Perera PY, Lee GM, Verma A, Hiroi T, Yokote H, Waldmann TA, Perera LP

An intense effort has been launched to develop a more optimal anthrax vaccine that can be rapidly deployed because of the inadequacies associated with the currently licensed vaccine. Protective antigen (PA)-based vaccines are most favored as immune responses directed against PA are singularly protective, although the actual protective mechanism remains to be unraveled. Herein we show that contrary to the prevailing view, an efficacious PA-based vaccine confers protection against inhalation anthrax by preventing the establishment of a toxin-releasing systemic infection. Equally importantly, antibodies measured by the in vitro lethal toxin neutralization activity assay (TNA) that is considered as a reliable correlate of protection, especially for PA protein-based vaccines adjuvanted with aluminum salts appear to be not absolutely essential for this protective immune response.