title: Comparative virulence of intra- and interstrain lipopolysaccharide variants of Coxiella burnetii in the guinea pig model.
abstract: We compared the relative infectivity and virulence of lipopolysaccharide (LPS) variants of the Nine Mile strain of Coxiella burnetii with those of the Priscilla strain, a representative of endocarditis-type strains. In agreement with results of previous studies, Nine Mile phase I (9mi/I) organisms were highly infectious, eliciting seroconversion and fever with inocula containing as few as four organisms. Viable 9mi/I was recovered from the spleens of infected animals 30 days postinfection. Nine Mile phase II (9mi/II) organisms did not elicit fever or seroconversion except with very large inocula, and viable organisms could not be recovered at 30 days postinfection. The Nine Mile/Crazy variant, bearing the intermediate-type LPS, was also highly infectious, as determined by fever response and seroconversion, although, as with 9mi/II, viable organisms could not be recovered 30 days postinfection. The Priscilla strain in phase I (Pris/I) was as infectious as 9mi/I, as determined by seroconversion and its presence in the spleen 30 days postinfection; but in contrast to 9mi/I, more than 10(5) Pris/I isolates were required to induce fever. The temporal appearances of anti-phase I and II antibodies were similar for the two strains. A variety of serological techniques measuring antibody response against whole-cell and purified LPS antigens in agglutination, immunofluorescence, enzyme-linked immunosorbent, and immunoblot assays did not demonstrate sufficient specificity to distinguish between 9mi/I and Pris/I infections. Results of vaccine cross-challenge experiments showed a significant degree of protection between homologous and heterologous challenge strains. protection between homologous
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D001428:Bacterial Vaccines / Q000302:isolation & purification / Q000494:pharmacology; D003381:Coxiella / Q000276:immunology*; D004195:Disease Models, Animal; D005260:Female; D006168:Guinea Pigs; D008070:Lipopolysaccharides / Q000276:immunology / Q000302:isolation & purification / Q000633:toxicity*; D011749:Pyrogens; D011778:Q Fever / Q000209:etiology* / Q000517:prevention & control; D013045:Species Specificity
chemical_list: D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D008070:Lipopolysaccharides; D011749:Pyrogens