Comparative electrophoresis of spotted fever group rickettsial proteins.

Electrophoretic analyses were performed to establish the polypeptide profiles of the following tick-borne typhus rickettsiae of the spotted fever group: $\text{Rickettsia rickettsii}$ (Sheila Smith, Bitter Root, Iowa and R strains), $\text{R. sibirica}$, $\text{R. conorii}$, $\text{R. parkeri}$, $\text{R. australis}$ and $\text{R. akari}$. Organisms were propagated in chick embryo fibroblast cells in roller bottles and purified by density centrifugation. After polyacrylamide gel electrophoresis, comparative electrophoretic profiles were examined by densitometric scanning. Of the more than 20 separate polypeptides detected, six of the most prominent were found in all rickettsiae examined except $\text{R. akari}$. No carbohydrate-containing moieties were detected in electrophoretic gels.