[Meningococcal plasmids]. / Plazmidy meningokokka.

In Neisseria meningitidis strains isolated from patients with meningococcal infection and from carriers, the presence of plasmids has been detected by the modified method of H. C. Bernboim and J. Doly. The strains have been studied with respect to their pathogenicity and sensitivity to antibacterial substances. No correlation between the presence of plasmids and pathogenicity factors, such as antilysozyme activity, the presence of hyaluronidase and the positive reaction to Congo red, resistance to penicillin, serogroup and the sources of isolation, has been established.

[Adhesion in meningococcus]. / Adgeziia u meningokokka.

The adhesive activity of 113 meningococcal strains with different invasive properties and 10 Neisseria nonpathogenic strains have been studied. Adhesive properties have been revealed in 80-82% of these strains. Meningococcal strains isolated from the nasopharynx of carriers possess high hemagglutinating activity. The percentage of cells with pili in these strain was also higher than that in meningococcal strains isolated from the liquor of patients. This shows the presence of direct correlation between the number of pili in the cells (according to the data of electron microscopy) and their activity in the hemagglutination test, which makes it possible to use this test for the determination of the adhesive capacity of meningococci, associated with the presence of pili.

[Interaction of Neisseria meningitidis with eukaryotic cells in a mixed infection in vitro]. / Vzaimodeistvie Neisseria menigitidis s éukarioticheskimi kletkami v usloviiakh smeshannoi infektsii in vitro.

To study the adhesion of meningococci under the conditions of a monoinfection and mixed infection (in association with influenza virus), the experimental model of mixed influenzal and meningococcal infection has been created in the culture of epithelial cells HEp-2. On this model in increase in the intensity of the adhesion of meningococci to eukaryotic cells, as well as in the intensity of the meningococcal colonization of such cells, after their preliminary infection with influenza virus has been observed. The study has revealed that in mixed infection the adsorption of extracellular virions onto the surface of bacteria occurs. During this adsorption viral processes directly interact with the microcapsule of the meningococcus.

[Preventive and therapeutic action of sera to the Re mutant of Salmonella minnesota in experimental generalized meningococcal infection]. / Preventivnoe i lechenoe deistvie syvorotok k Re-mutantu Salmonella minnesota pri éksperimental'noi generalizovannoi meningokokkovoi infektsii.

The preparations of the blood plasma of humans and the sera of animals immunized with enterobacterial vaccine proved to have elevated titers of antibodies to deep determinants of the core of the gram-negative bacterial endotoxin molecule (to glycolipid of chemotype Re) and protected animals from infection with live cultures or serogroup A, B, or C meningococcal endotoxins. Sera from nonimmunized animals and normal donor blood plasma showed no protective activity. In experiments carried out on different models immune plasma possessed both a pronounced protective activity and a curative effect. The efficacy of protection depended not on the serogroup of the infective agent, but on the virulence of the strain used in the experiment, being statistically significant in all cases.

[A common meningococcaL intergroup antigen: immunological and immunochemical study]. / Obshchii mezhgruppovoi antigen meningokokka: immunologicheskoe i immunokhimicheskoe izuchenie.

Protein-containing preparations forming 1 precipitation line in highly sensitive immunoelectrophoretic tests have been obtained from the culture fluid of meningococci, groups A, C and X. The preparations have been found to render a very high degree of protection to mice challenged with meningococci of the homologous serogroup and a sufficiently high degree of protection to those challenged with meningococci of the heterologous serogroups. After the repeated injection of the preparations the appearance of the booster effect has been registered. Immunochemical study has shown that the preparation is a stable complex consisting of protein, group-specific polysaccharide and a heat-resistant component common for serogroups A, C, X and Y.

[Epidemiological significance of carriers of hyaluronidase-active meningococci]. / Epidemiologicheskoe znachenie nositelei gialuronidazoaktivnykh meningokokkov.

To find out the epidemiological role of the carriers of hyaluronidase-positive meningococcal strains, their spread in the foci of meningococcal infection, as well as outside these foci, was studied. For this purpose, altogether 5059 persons from 40 family foci of infection and 40 organized groups were examined. The number of carriers of hyaluronidase-active meningococci, detected among those of them who had contacts with sick persons, was 13 times greater than among the persons having no such contacts. In preschool institutions with unfavorable morbidity situation this number was 16 times greater than in those with favorable situation. In the family foci carriers of hyaluronidase-active meningococci constituted 80-88 %. The percentage of the carriers of hyaluronidase-active meningococci causing cases of the generalized form of meningococcal infection varied in different groups. According to the results obtained in this study, the threshold percentage of such carriers constituted 30 in preschool institutions, 36 in boarding schools and 50 in common school and in hostels for adults.

[Natural reproduction of all stages of a generalized meningococcal infection in mice]. / Vosproizvedenie estestvennym putem vsekh étapov generalizovannoi meningokokkovoi infektsii na myshakh.

The present work is based on the direct relationship, revealed in our investigations, between the hyaluronidase activity of meningococcal strains and their capacity to penetrate into the blood and the liquor. The use of the intranasal route (i.e. the natural route) for infecting previously untreated mice with meningococci in the presence of hyaluronidase made it possible to follow the generalized form of meningococcal infection in all its stages from the period of incubation and microbial invasion to bacteriemia, accompanied by the penetration of the infective agent into the meninges, and toxinemia. This route of infection ensured the penetration of the infective agent, but the natural specific resistance of mice to meningococci prevented their multiplication with the subsequent liberation of a sufficient amount of endotoxin killing the animals. To overcome natural immunity and increase toxicity, actinomycin D was injected intraperitoneally in a volume of 0.5 ml (5 gamma) simultaneously with the administration of the microbial culture and hyaluronidase, thus ensuring 40-60% mortality among the animals. Our model of the generalized form of meningococcal infection can be used in the study of pathogenesis and for the development of the methods of treatment and microbiological diagnosis.

[Epidemiological evaluation of the serological grouping of meningococci]. / Epidemiologicheskaia otsenka serologicheskogo gruppirovaniia meningokokkov.

Use of the precipitation and hemagglutination inhibition tests to determine the serological group of 114 meningococcus strains which cannot be grouped by agglutination slide permitted to establish the serological group of 56% of the strains, this pointing to the greater diagnostic value of these tests. Nevertheless, 70% of 307 strains isolated from carriers could not be referred to any of the determinable groups (A, C, X, Y, and Z). Strains (417) isolated from the cerebrospinal fluid of patients with meningitis were grouped depending on the epidemic curve: only half of the cultures could be classified in sporadic cases, but from 80 to 100% of the strains were classified at the "peak" of the meningitis incidence rise. This rise was connected with increase of the incidence of cases caused by meningococcus, group A; at the decline these strains were eliminated, and cases due to the rarely encountered serological groups and nongrouping strains occurred. Marking meningococc by serological groups proved to be of no use for detection of epidemiological relations between the infected persons.

[Hyaluronidase in meningococcus]. / Gialuronidaza u meningokokka.

A total of 204 meningococcus strains were tested for the presence of hyaluronidase, and 45.5% of the strains were found to contain it. Strains penetrating into the cerebrospinal fluid were the ones which largely produced the enzyme (in 83% of the cases). The enzyme was revealed only in 25.5% of the strains habituating on the nasopharyngeal mucosa. Hyaluronidase was mostly found in the meningococcus strains referred to the serological group A; strains of other serological groups and ungrouped strains produced the enzyme in 23.7% of the case only. There was no correlation between the capacity to form hyaluronidase and the virulence determinable in intraperitoneal infection of mice.