[The need for a review of the procedure for the preventive vaccination of researchers working with Rickettsia prowazekii]. / Neobkhodimost' peresmotra taktiki profilakticheskoi vaktsinatsii sotrudnikov, rabotaiushchikh s Rickettsia prowazekii.

The analysis of the results of prolonged observations on the prophylactic immunization of employees working with R. prowazekii is presented. The necessity of the differentiated approach to the determination of the immunization schedule and the choice of vaccine is shown. The presence of specific antibodies (Ab) and the level of their titers have been found to be related to the degree of anti-infectious protection. The following characteristics indicate the presence of profound immunological transformation in vaccinees: complement-fixing Ab in titers 1:10 and more and/or immunofluorescent Ab in titers not below 1:180, Ab to protein in the hemagglutination test in titers not below 1:1000. These specific Ab and the level of their titers can be registered after the second injection of live combined typhus vaccine E and the third injection of chemical typhus vaccine. Cases of laboratory infection and their relationship to the character of immunization and the intensity of contacts with R. prowazekii virulent strains are discussed. Attention is drawn to the strict observance of professional safety rules.

Electron microscopic analysis of in vitro interaction of Rickettsia prowazekii with guinea pig macrophages. II. Macrophages from immune animals.

Alike to macrophages from intact animals, reproduction, destruction and formation of spheroplast-like forms were observed in macrophages from immune guinea pigs 2 months post-infection (p.i.) with the virulent Breinl strain of Rickettsia prowazekii. Unlike to the former, immune macrophages revealed phagolysosomes which were larger in size and contained more rickettsiae showing morphologic signs of destruction. Spheroplast-like forms occurred more often and were more numerous than in intact animals. Structures morphologically similar to L-forms of gram-negative bacteria and that of chlamydiae were also detected. After adding immune serum, more intact rickettsiae and spheroplasts were found in phagosomes as well as more phagolysosomes contained rickettsiae and spheroplasts with morphologic signs of destruction. It is suggested that clearance of immune macrophages from rickettsiae is mediated by at least two processes: on one hand by destruction of rod-shaped rickettsiae within phagolysosomes and, on the other hand, by formation and subsequent destruction of spheroplast-like forms within vacuoles, which probably also function as phagolysosomes.

Electron microscopic analysis of in vitro interaction of Rickettsia prowazekii with guinea pig macrophages. I. Macrophages from nonimmune animals.

Monolayer cultures of peritoneal macrophages of intact guinea pigs were infected with Rickettsia prowazekii (strain Breinl) and examined by electron microscopy after 30 min, 4 and 24 hr post-infection (p.i.). Three parallel processes developed in infected macrophages: reproduction of rickettsiae in macrophage cytoplasm, destruction in phagolysosomes and production of spheroplast-like forms. Reproduction of rickettsiae yielded 2 cell types: those with dense and with light cytoplasm; they were located side by side in the microcolony and seemed to have a common capsule-like coat. Relatively small spheroplast-like forms of about 1 micron in size were regularly detected. Addition of immune serum to macrophages increased the number of rickettsiae, both of rod-shaped as well as of spheroplast-like ones located within phagosomes, but elicited no increase in the number of digested pathogen cells.

[Electron microscopic characteristics of the action of penicillin and vancomycin on Rickettsia conorii and Rickettsia akari in vitro]. / Elektronno-mikroskopicheskaia kharakteristika deistviia penitsillina i vankomitsina na Rickettsia conorii i Rickettsia akari in vitro.

The possibility of L-transformation for two species of Rickettsia of the tick group (R. conorii and R. akari) was studied with light and electron microscopy. The experiments were performed on the cultures of L-cells (murine fibroblasts). Penicillin and vancomycin were used as the transforming agents. Electron microscopy revealed clear changes in the morphological structure of both species when the doses of penicillin and vancomycin were 50-100 and 250-1500 micrograms/ml, respectively. The antibiotics had a morphologically analogous effect on both species of Rickettsia. The resulting morphological structures were large oval spheroplast-like cells with significant expansion of the periplasmic space up to 1 X 1.75 micron under the effect of penicillin and 0.5 X 0.7 micron under the effect of vancomycin. R. akari was somewhat more sensitive to the antibiotics. Electron microscopy of the morphological changes in the Rickettsia induced by penicillin and vancomycin showed that they were similar to the changes observed in gram-negative bacteria on their L-transformation and to the penicillin forms of chlamydia (galprovia) and R. prowazekii. They may be considered as a phase of unbalanced growth and represent the initial stage of L-transformation.