Study on toxicity of Bordetella pertussis cultures and antigens.

The toxicity of 201 Bordetella pertussis strains isolated in Belgrade has been studied. The strains were grown on a modification of Cohen and Wheeler's medium. LD50 of examined strains ranging between 1.06 and 1.95 billion bacteria in 35 (17.41%), between 2.04 and 4.83 billion bacteria in 92 (45.77%) and between 5.31 and 7.79 billion bacteria in 46 (22.88%) were found. Low toxic cultures of B. pertussis strains with LD50 ranging between 9.0 and 14.1 billion bacteria in 28 (13.43%) were obtained. The culture of the strains with low toxicity was 7 to 14 times more toxic than those prepared from the strains with low toxicity. In the cultures of 51 B. pertussis strains, toxicity for mice was not correlated with the number of viable cells. The toxic substances which influenced the loss of mouse weight were found in the culture filtrate of B. pertussis. A considerable detoxifying effect of heating at 56 degrees C for 30 min on liquid cultures prepared from highly toxic strains of B. pertussis was observed. The susceptibility of two different strains of mice for pertussis vaccine has been examined. The Albany strain of mice was less susceptible to toxicity control of the vaccine by mouse-weight-gain test than the Torlak strain.