[Antigenic structure of endotoxins from Bacillus thuringiensis].

The proteins of parasporal crystals of 9 strains of entomopathogenic bacteria of the Bacillus thuringiensis group of different H-serotypes were studied by different methods. Electrophoresis showed that crystals from the bacteria of 1, 3, 4, 5, 8, and 10 serotypes contained 1-2 proteins with a molecular weight of 130-145 kD and an additional fraction with a molecular weight of 55-120 kD. Double-radial immunodiffusion revealed that the crystals of all the serotypes studied are immunologically related. The proteins contained at least 3 types of antigens that can be detected either separately or all together when being tested with different antisera. The ELISA technique showed that the crystal proteins homologous with respect of antigens gave, as a rule, similar titration results.