Evaluation of Bacillus anthracis extractable antigen for testing anthrax immunity

Area of Science:

• Immunology
• Microbiology
• Veterinary Medicine

Background:

• Bacillus anthracis causes anthrax, a significant zoonotic disease.
• Accurate diagnosis and assessment of immunity are crucial for disease control.
• Current diagnostic methods may have limitations in assessing cell-mediated immunity.

Purpose of the Study:

• To evaluate three Bacillus anthracis cell-wall-associated antigens as potential diagnostic tools.
• To assess their utility in skin testing and in-vitro diagnosis of anthrax immunity.
• To identify the most effective antigen for detecting immune responses.

Main Methods:

• Production of anthraxin and partially purified extractable antigen (EAP) from avirulent B. anthracis.
• Commercial acquisition of thermoextractable antigen for the Ascoli reaction.
• Immunization of guinea pigs with Sterne live veterinary anthrax vaccine.
• Skin testing with the three antigens post-vaccination.
• Determination of serum antibody levels via ELISA.
• Evaluation of in-vitro T-cell response using [3H]-thymidine incorporation.

Main Results:

• Extractable antigen (EAP) demonstrated the highest activity in both serological and cellular immune reactions.
• EAP successfully elicited a distinct positive skin reaction in immunized animals.
• ELISA and T-cell proliferation assays correlated with EAP's efficacy.

Conclusions:

• Extractable cell-wall antigens from vegetative B. anthracis are viable candidates for diagnostic applications.
• EAP shows significant potential for use in skin tests to assess anthrax immunity.
• These antigens may facilitate both in-vitro and in-vivo evaluation of humoral and cell-mediated immunity to anthrax.