[Some properties of the alpha-hemolysin produced by a hemolytic strain of E. coli]. / Nekotorye svoistva al'fa-gemolizina, produtsiruemogo gemoliticheskim shtammom E. coli

It was found that alpha-hemolysin of E. coli P 678 HIy+ was maximally active against human erythrocytes at pH 6.5. The hemolytic activity is characterized in time by a distinct lag-phase and a phase of the greatest velocity of the reaction immediately following it. The duration of the lag-phase and also the rate of hemolysis depends on alpha-hemolysin concentration, whose increase is accompanied by a decrease of the lag-phase and acceleration of hemolysis. There is a definite limit below which the duration of the lag-phase remains unchanged with further increase of hemolysin concentration. There was noted a linear relationship between the amount of erythrocytes taken for the test and the rate of hemoglobin release and also a temperature activation of the hemolytic reaction.

[Preliminary electron microscopic and x-ray study of the crystalline protein of diphtheria toxin]. / Predvaritel'noe élektronno-mikroskopicheskoe i rentgenovskoe izuchenie kristallicheskogo belka difteriinogo toksina

The authors present the results of the electron microscopic and roentgenological study of the crystalline protein of diphtheria toxin. On the basis of direct measurements of the crystal image and diffraction pictures it was possible to calculate the interplane distances of the placement of molecules in the crystal. Examination in polarization microscope showed that the crystals were optically uniaxial with a direct extinction and a positive character of elongation. Molecular aggregates revealed in the protein molecules resembled the caudal part of the bacteriophage by structure.

[Immunochemical study of the meningococcal cell wall]. / Immunokhimicheskoe izuchenie kletochnoi stenki meningokokkov

Meningococcus strains--standard and those isolated from the cerebrospinal fluid of patients suffering from the cerebrospinal meningitis were grown on fluid and solid protein-free nutrient media. Electron microscopic study showed that in the strains isolated from patients the wall was much thicker than in the standard strains. The cell wall preparations were obtained by its solution at pH 9.0 and separation from the microbial residue. In the cultures grown on the solid medium the cell was dissolved already in its washing at pH 7.2. It was revealed in gel filtration that the cell wall preparations consisted of three fractions. The fraction with the mol wt of from 2 to 3 million possessed a complex protein-polysaccharide nature, contained all the antigens of the group and intergroup specificity, was nontoxic for mice and antigenic for rabbits. Two other fractions whose mol wt was below 67000 contained no antigens.

[Changes in the surface structures of bacteria as a cause of weak immunogenicity of vaccines from several strains of Citrobacter]. / Izmenenie poverkhnostnykh struktur bakterii kak prichina slaboi immunogennosti vaktsin iz nekotorykh shtammov Citrobacter

The authors present the results of studying the weakly immunogenic Citrobacter strains; some O-antigens of Citrobacter (11, 14, 19, 21a, 21b, 26) caused in immunization of rabbits a weak immune response (antibody titre--1:400-1:800). An electron microscopic study of the vaccines (obtained from these strains) and their fragments showed that a partial desquamation and denaturing of the antigenic material occurred in the process of preparation of heated vaccines. Formalin-treated vaccine subjected to preliminary deflaggelation for 2 min at 3000 cps was used for obtaining the O-sera against the mentioned antigens.