[The assessment of antitoxic anti-anthrax immunity]

In experiments on guinea pigs immunized with avirulent noncapsular strains STI, Sterne (34F2) and the avirulent mutant of Bacillus anthracis strain 228/8 the relationship between the titers of serum antibodies to the preparations of purified protective antigens (PA) and purified lethal factor (LF) of B. anthracis toxin and the level of the antitoxic activity (ATA) of blood sera, as well as acquired resistance, was analyzed. The ATA of sera was evaluated in the primary culture of peritoneal macrophages affected by the mixture of PA and LF. The level of relationship (r) between individual ATA values and the titers of antibodies to PA and LF was shown to vary over a wide range, depending on the group of the animals and did not exceed, on the average, 0.19-0.37. At the same time the mean values of these characteristics, followed in their dynamics depending on the immunogenic properties of vaccine strains or the time elapsed after vaccination, were highly correlated (r = 0.76-0.87). The possibility of using these characteristics for the evaluation of acquired resistance are discussed.