A simple chemical procedure has been outlined for the isolation of a fraction from H. pertussis which has the following properties:
It is antigenic; when injected into rabbits intravenously, it gives rise to agglutinins against H. pertussis in phase I.
It absorbs quantitatively agglutinins from H. pertussis antiserum.
It is non-toxic, as demonstrated by tests on rabbits and human beings.
It has been used successfully as a material for skin-tests for susceptibility to whooping-cough.
The agglutinogen may well serve as a means of reinforcing waning active immunity to pertussis.
This work was aided by a grant from the United States Public Health Service.