Development of a rapid immunochromatographic assay for detection of surface array protein (Sap), a potent biomarker of Bacillus anthracis

Bacillus anthracis, the causative agent of anthrax poses serious threat to human health. Genetically, B. anthracis is very close to the other species of this group. Hence, it is important to develop a rapid screening test for B. anthracis . Surface array protein (Sap), a surface layer protein produced by B. anthracis is considered an important biomarker for its detection as it is excreted in the growth media. In the present study, we have developed an Immunochromatography test (ICT) strip for detection of Sap, for rapid screening of B. anthracis strains. The recombinant Sap was produced and used for production of mouse monoclonal antibodies. The antibodies were conjugated with colloidal gold for preparation of ICT. For determination of sensitivity and specificity, different Bacillus species were grown in culture broth, heat inactivated to kill the live bacteria and tested on ICT. The B. anthracis Sterne could be detected after 3 h of growth. Sample testing by ICT takes only 2 min in comparison to 4–5 h in sandwich plate ELISA. The results corroborated that the ICT can be used for rapid screening of B. anthracis isolates. The proposed method is rapid, safe and user friendly for detection of B. anthracis culture.