title: Fraction 1 capsular antigen (F1) purification from Yersinia pestis CO92 and from an Escherichia coli recombinant strain and efficacy against lethal plague challenge.
abstract: As a first step in formulating an improved plague vaccine, we developed a simple purification strategy that produced high yields of pure cell-associated and culture supernatant-derived fraction 1 capsular antigen (F1) from both avirulent Yersinia pestis C092 (Pgm- Lcr-) and an Escherichia coli F1-producing recombinant strain. Cell-associated F1 was partially purified by sequential ammonium sulfate precipitations of a sodium chloride extract of acetone-dried bacteria harvested from broth cultures. Cell-free F1 was precipitated directly from culture supernatants with a single application of 30% ammonium sulfate. By exploiting the aggregative property of F1, large quantities of purified high-molecular-weight F1 species from both cell extracts and supernatants were isolated in the void volume of a preparative gel filtration column. Highly purified, endotoxin-free F1, combined with two different adjuvants, induced very high F1 titers in mice and protected them against either subcutaneous (70 to 100% survival) or aerosol (65 to 84% survival) challenge with virulent organisms. This protection was independent of the source of the antigen and the adjuvant used. F1-induced protection against both subcutaneous and aerosol challenge was also significantly better than that conferred by immunization with the licensed killed whole-cell vaccine. Our results indicate that F1 antigen represents a major protective component of previously studied crude capsule preparations, and immunity to F1 antigen provides a primary means for the host to overcome plague infection by either the subcutaneous or respiratory route.
authors.affiliation: Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21702, USA.
authors.forename: G P
authors.initials: GP
authors.lastname: Andrews
authors.forename: D G
authors.initials: DG
authors.lastname: Heath
authors.forename: G W
authors.initials: GW
authors.lastname: Anderson
authors.forename: S L
authors.initials: SL
authors.lastname: Welkos
authors.forename: A M
authors.initials: AM
authors.lastname: Friedlander
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000276:immunology / Q000302:isolation & purification*; D002850:Chromatography, Gel; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D007114:Immunization; D051379:Mice; D010930:Plague / Q000517:prevention & control*; D011994:Recombinant Proteins / Q000302:isolation & purification; D015010:Yersinia pestis / Q000276:immunology*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D011994:Recombinant Proteins; C086725:caf1 protein, Yersinia pestis