Proteins of typhus and spotted fever group rickettsiae

Abstract

Purified radioactive rickettsiae were obtained from irradiated and cycloheximide-inhibited L cells, and their proteins were analyzed by polyacrylamide gel electrophoresis. Rickettsial species could be distinguished by comparing the relative mobilities of constituent proteins after migration of two differentially labeled preparations in a single gel. Distinct differences were observed in gel patterns of rickettsiae from the typhus and spotted fever groups, as well as with different species within a group. Rickettsial organisms causing murine and epidemic typhus were clearly distinguished, as were the causative agents of boutonneuse fever and rickettsialpox. The use of both internal and external molecular weight standards allowed molecular weight estimates for 19 proteins from both Rickettsia prowazekii and Rickettsia conorii. A flexible system for designating rickettsial proteins is proposed that lends itself to modification as more detailed analysis progresses.

Biochemical Characteristics of Typhus Group Rickettsiae with Special Attention to the Rickettsia prowazekii Strains Isolated from Flying Squirrels

“…1 are similar to those reported previously for R. canada, the Breinl strain of R. prowazekii, and the Wilmington strain of R. typhi (9,19) despite differences in growth con-ditions and/or purification procedure. In the previous studies, the rickettsiae were grown in L-929 cells and purified by sucrose gradient centrifugation (9) or grown in yolk sacs, pretreated with Formalin and Celite, and purified by glycerol-tartrate viscosity equilibrium gradient centrifugation (19). We demonstrated consistent dif- , .,l-M. Isw ferences among the protein patterns of R. canada, R. prowazekii, and R. typhi.…”

“…These principally include specific zymogram techniques for enzymes that have been separated by electrophoresis on starch or polyacrylamide gels (3,21), the comparison of the protein patterns of whole cells or various envelope fractions obtained by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) (1,7), or isoelectric focusing (20), and the comparison of relative activities of specific enzymes (12). Although several distinct differences have been demonstrated in the profiles of the proteins of highly purified R. typhi, R. prowazekii, and R. canada on neutral SDS-gels (9,19), too few strains oftyphus rickettsiae have been compared to determine the extent of such differences within each species.…”

“…These differences are labeled 1 through 9 in Fig. 1, but no attempt was made to identify each separable protein or to use the numbering system of previous authors (9,19). In sharp contrast, the protein patterns of the same species were identical.…”

Current Knowledge on Phylogeny and Taxonomy of Rickettsia spp.

“…10 Various methods were used to study Rickettsia species but failed to provide easily reproducible identification tools, including complement fixation, toxinic neutralisation, SDS-PAGE, mouse serotyping, Western blot, development of monoclonal antibodies, and DNA-DNA hybridization. [11][12][13][14][15][16][17] As a consequence, although initially discovered in the early XX th century, Rickettsia sp. remained badly known until the 1990s and the introduction of molecular tools, and still are a matter of debate, in particular, in regarding their taxonomy.…”

Production and characterization of cloned T-cell hybridomas that are responsive to Rickettsia conorii antigens

“…Cross-reactivity, particularly between R. rickettsii and R. conorii, is not surprising because there is greater than 90% DNA homology between the two species (3, 40). In addition, polypeptides common among SFG members have been demonstrated by electrophoresis (8). Shared SFG antigens capable of stimulating T-cell responses were investigated further in a recent study by Jerrells et al (17), in which spleen cells from R. conorii Malish-immunized mice proliferated in vitro when these cells were stimulated with the antigens of all tested strains of R. conorii (Malish, * Corresponding author.…”