beta-Lactamase from Bacillus licheniformis 749/c was used as a marker for ELISA. Conjugates of the beta-lactamase with the capsule antigen of the plague causative agent and with the monoclonal antibodies to it were prepared by glutaric aldehyde "linking". The conjugates preserved high immunospecific and beta-lactamase activity. High sensitivity of the modification of ELISA allowed detecting up to 8 ng/ml of the capsule antigen of the plague causative agent. The enzymatic activity of the beta-lactamase was determined microiodometrically which provided visual recording of the results of ELISA.
Antibodies, Monoclonal Antigens, Bacterial