title: Cross-protection between distantly related spotted fever group rickettsiae.
abstract: Two excellent C3H/HeN mouse models of spotted fever rickettsioses caused by the distantly related organisms, Rickettsia conorii and Rickettsia australis, were utilized to evaluate the possibility of the stimulation of broad cross-protective immunity. Sublethal infection stimulated complete immunity, that is absence of disease, after challenge with a dose of the heterologous Rickettsia that uniformly killed naïve mice. In contrast, heterologous immune sera did not protect mice against a lethal dose (two LD50) of rickettsiae in the mouse toxicity neutralization assay, the standard method for evaluation of rickettsial vaccine potency. These observations suggest that development of a broadly protective vaccine against spotted fever group (SFG) rickettsiae is feasible, and the results indicate that mouse toxicity neutralization is an inappropriate method for evaluation of candidate vaccines.
authors.affiliation: Department of Pathology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0609, USA.
authors.forename: Hui-min
authors.initials: HM
authors.lastname: Feng
authors.forename: David H
authors.initials: DH
authors.lastname: Walker
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis / Q000096:biosynthesis; D000918:Antibody Specificity; D003429:Cross Reactions; D003974:Diatrizoate Meglumine; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D009500:Neutralization Tests; D020114:Rickettsia conorii / Q000276:immunology*; D012284:Rickettsia rickettsii / Q000276:immunology* / Q000302:isolation & purification; D012373:Rocky Mountain Spotted Fever / Q000517:prevention & control*
chemical_list: D000907:Antibodies, Bacterial; D003974:Diatrizoate Meglumine