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Updated: Jun 19, 2026
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An Electroporation Method to Transform Rickettsia spp. with a Fluorescent Protein-Expressing Shuttle Vector in Tick Cell Lines
Published on: October 11, 2022
THE ANTIGENIC RELATIONSHIP BETWEEN PROTEUS X-19 AND TYPHUS RICKETTSIA : II. A STUDY OF THE COMMON ANTIGENIC FACTOR
1Department of Bacteriology and Immunology, The Harvard Medical School, Boston.
The Journal of Experimental Medicine
|October 30, 2009
Summary
Researchers identified a common soluble specific factor between Mexican typhus Rickettsia and Proteus OX-19. This shared factor, likely a polysaccharide, is responsible for the Weil-Felix reaction in typhus diagnostics.
Area of Science:
- Microbiology
- Immunology
- Rickettsial Diseases
Background:
- The Weil-Felix reaction is a serological test used to diagnose typhus group rickettsioses.
- This reaction involves agglutination between patient serum and specific strains of Proteus bacteria.
- The underlying antigenic relationship between Rickettsia and Proteus strains has been a subject of investigation.
Purpose of the Study:
- To isolate and characterize the soluble specific substance from Mexican typhus Rickettsia.
- To compare this substance with polysaccharides from B. proteus OX-19.
- To elucidate the antigenic basis of the Weil-Felix reaction.
Main Methods:
- Isolation of a soluble specific substance from Mexican typhus Rickettsia.
- Precipitation reactions using Proteus X-19 antiserum and typhus human serum.
- Chemical tests including Molisch reaction and biuret test to determine the nature of the substance.
Main Results:
- A soluble specific substance was isolated from Mexican typhus Rickettsia.
- This substance exhibited identical precipitation reactions to polysaccharides from B. proteus OX-19.
- The substance showed characteristics of a polysaccharide (positive Molisch, heat stable, negative biuret) but contained 7% nitrogen.
- A common soluble specific factor was identified in both typhus Rickettsia and Proteus X-19.
Conclusions:
- A shared soluble specific factor exists between typhus Rickettsia and Proteus X-19.
- This common factor is likely responsible for the serological cross-reactivity observed in the Weil-Felix reaction.
- The substance is predominantly polysaccharide in nature, though further investigation into its exact composition is warranted.
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