Proteome and Antigen Profiling of Coxiella burnetii Developmental Forms

Abstract

A biphasic developmental cycle whereby highly resistant small-cell variants (SCVs) are generated from large-cell variants (LCVs) is considered fundamental to the virulence of Coxiella burnetii, the causative agent of human Q fever. In this study a proteome analysis of C. burnetii developmental forms was conducted to provide insight into their unique biological and immunological properties. Silver-stained gels of SCV and LCV lysates separated by two-dimensional (2-D) gel electrophoresis resolved over 675 proteins in both developmental forms. Forty-eight proteins were greater than twofold more abundant in LCVs than in SCVs, with six proteins greater than twofold more abundant in SCVs than in LCVs. Four and 15 upregulated proteins of SCVs and LCVs, respectively, were identified by mass spectrometry, and their predicted functional roles are consistent with a metabolically active LCV and a structurally resistant SCV. One-dimensional and 2-D immunoblots of cell form lysates probed with sera from infected/vaccinated guinea pigs and convalescent-phase serum from human patients who had recovered from acute Q fever, respectively, revealed both unique SCV/LCV antigens and common SCV/LCV antigens that were often differentially synthesized. Antigens recognized during human infection were identified by mass spectroscopy and included both previously described immunodominant proteins of C. burnetii and novel immunogenic proteins that may be important in the pathophysiology of clinical Q fever and/or the induction of protective immunity.

Isolation from Animal Tissue and Genetic Transformation of Coxiella burnetii Are Facilitated by an Improved Axenic Growth Medium

“…3A and B). Colonies in ACCM-2 agarose were primarily comprised of the small cell variant (SCV) form of C. burnetii as assessed by size and characteristic condensed chromatin (9) (Fig. 3C).…”

Immunoproteomics: From biomarker discovery to diagnostic applications

“…It is, therefore, not a surprise that antipathogen antibodies are good markers for the diagnosis of parasital, fungal, microbial and viral infection [79]. Moreover, profiling the intensity and specificity of the antipathogen responses provides a comprehensive view of the complexity and interindividual heterogeneity of the hostresponses, and variations in the antigenicity of pathogens [80].…”

A Genome-Wide Proteome Array Reveals a Limited Set of Immunogens in Natural Infections of Humans and White-Footed Mice withBorrelia burgdorferi

“…Detection of a specific antibody during the course of infection is indirect evidence of in vivo expression by the pathogen. But the use of this approach to study large numbers of proteins has been largely limited to one-dimensional and two-dimensional gel electrophoresis of whole cells having an in vitro origin, followed by identification of the more abundant antigens by partial amino acid sequencing of reactive bands or spots and then searches of the databases (22,23,38,44,52,60,66). …”