STUDIES ON THE SOLUBLE PRECIPITABLE SUBSTANCES OF VACCINIA : III. THE PRECIPITIN RESPONSES OF RABBITS TO THE LS ANTIGEN OF VACCINIA.

Observations on antibody production in the rabbit in response to the injection of the LS antigen of vaccinia have shown that this antigen retains its ability to stimulate the production of L and S antibodies, not only when it is in a state of solution as found in lapine Seitz filtrates, but also after it has been partially purified. As reported in previous papers, both the L and S antibodies participate (a) in the true agglutination of washed elementary bodies, (b) in the precipitation of the soluble LS antigen found in fresh vaccine suspensions or dissociated in vitro from washed elementary bodies. The difference in the thermostability of the L and S components of the LS antigen as far as their reactivity in vitro is concerned, holds in respect of their capacity to stimulate antibody production. Heating at 70 degrees C. invariably abolishes the antigenicity of the L component while the S component remains antigenic after being heated to 90 degrees C.