Immunoreactive Coxiella burnetii Nine Mile proteins separated by 2D electrophoresis and identified by tandem mass spectrometry

Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164, USA.
Microbiology (Impact Factor: 2.56). 10/2010; 157(Pt 2):526-42. DOI: 10.1099/mic.0.043513-0
Source: PubMed


Coxiella burnetii is a Gram-negative obligate intracellular pathogen and the causative agent of Q fever in humans. Q fever causes acute flu-like symptoms and may develop into a chronic disease leading to endocarditis. Its potential as a bioweapon has led to its classification as a category B select agent. An effective inactivated whole-cell vaccine (WCV) currently exists but causes severe granulomatous/necrotizing reactions in individuals with prior exposure, and is not licensed for use in most countries. Current efforts to reduce or eliminate the deleterious reactions associated with WCVs have focused on identifying potential subunit vaccine candidates. Both humoral and T cell-mediated responses are required for protection in animal models. In this study, nine novel immunogenic C. burnetii proteins were identified in extracted whole-cell lysates using 2D electrophoresis, immunoblotting with immune guinea pig sera, and tandem MS. The immunogenic C. burnetii proteins elicited antigen-specific IgG in guinea pigs vaccinated with whole-cell killed Nine Mile phase I vaccine, suggesting a T cell-dependent response. Eleven additional proteins previously shown to react with immune human sera were also antigenic in guinea pigs, showing the relevance of the guinea pig immunization model for antigen discovery. The antigens described here warrant further investigation to validate their potential use as subunit vaccine candidates.

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    • "Some protein spots were assigned to more than one protein, possibly because the proteins co-migrated as a result of having the same pI and molecular weight. This pattern of co-migration is not uncommon in proteomic studies and was reported previously [23,24]. The 31 up- and 22 down-regulated X. a. pv. "
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    • "Unfortunately, we were unable to express CBU_1718 in our study. Our best diagnostic marker of acute Q fever was CBU_0092 (Appendix S1), which was previously reported as a good marker (Beare et al., 2008; Deringer et al., 2010; Vigil et al., 2010, 2011; Papadioti et al., 2011). Its diagnostic power was strong enough for the general diagnosis of Q fever and might the better specificity for acute Q fever (L = 22). "
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    • "In addition, several biomarkers were selected using immunoproteomic studies [31,57,68] and were reported to be promising proteins for Q fever serodiagnosis. In a large-scale comprehensive study, only about 1% of the whole proteome of C. burnetii expressed in vitro showed seroreactivity [69]. "
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