Rapid and sensitive Lethal Factor immunoassay for early diagnosis of anthrax
Résumé
Bacillus anthracis is a gram-positive, spore forming bacterium responsible of anthrax in humans and animals. It is considered one of the most potent and dangerous biological weapon and in this regard has been classified as a category A potential biological warfare agent by the United states Centers for Disease Control and prevention (CDC). Very early after infection components of anthrax toxin: the protective antigen (PA), the lethal factor (LF) and the edema factor (EF), are secreted and circulate in blood before bacteria are detectable and before emergence of any clinical signs. Early and rapid diagnosis is essential to improve survival, particularly in cases of anthrax inhalation almost 100% fatal without treatment. In this context, we have produced monoclonal antibodies against LF and developed sensitive and rapid ELISA (result time ≤ 3 hours) and lateral flow immunoassay (LFIA, result time ≤ 30 min). A limit of detection (LoD) of 1 pg/ml of LF by ELISA and 31 pg/ml by LFIA were determined in buffer or two-fold diluted human serum. The analytical sensitivity of these tests appear suitable for early diagnosis of anthrax before the bacteria are detectable in blood and disseminate.