Homogeneity and Heterogeneity of Toxins Produced by Clostridium botulinum Type C and D Strains

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Abstract
Five C. botulinum strains were used in the present work, 2 of type C, C-Stockholm (C-ST) and C-CB19, and 3 of type D, D-South African (D-SA), D-1873 and D-CB16. The toxins, except for those of C-CB19 and D-CB16, were purified and antisera were prepared in rabbits. To clarify the antigenicity of the toxins, neutralization and agar gel double-diffusion tests were performed. Anti-C-ST toxin serum neutralized 2 kinds of type C1 toxin to a similar extent. Antisera against D-SA and D-1873 toxins showed different neutralizing activity toward 3 type D toxins. Precipitin lines formed between D-SA and D-1873 toxins, their antisera spurred to each other. From anti-D-SA toxin serum, 2 neutralizing fractions, 1 which neutralized D-SA, D-1873 and D-CB16 and 1 which neutralized only D-SA, were obtained. The antigenicities of D-SA and D-1873 toxins are evidently not identical. Anti-C-ST toxin serum produced cross-neutralization on type D toxins, although the neutralization titer differed depending on the kind of toxin used. A precipitin line was formed with D-SA toxin, but not with D-1873; the developed line spurred to the C-ST toxin precipitin line. Two anti-D toxin sera also caused cross-neutralization on type C1 toxins. The neutralizing activity of each serum to the same type C1 toxin was different; only anti-D-SA toxin serum developed a precipitin line with C-ST toxin which spurred to the D-SA toxin precipitin line. From anti-D-SA toxin serum, 2 different fractions capable of neutralizing C1 and D toxins were obtained; 1 neutralized C-ST, C-CB19 and D-SA toxins, but not D-1873 and D-CB16; the other neutralized all 5 toxins. There may be at least 2 common parts among C-ST, C-CB16 and D-SA toxin molecules.