Public health applications of quantitative protein biomarkers

Protein biomarkers are playing an increasingly important role in public and environmental health, due in part to recent advances in genomics, bioinformatics and mass spectrometric instrumentation. Newly available enabling technologies allow for the system-wide examination of entire proteomes of microorganisms and human specimens for an in-depth determination of environmental stress responses and specific biomarkers of toxic exposure. This doctoral thesis concentrated on the application of contemporary mass spectrometric techniques for the qualitative and quantitative detection of proteomic biomarkers in complex samples, specifically bacterial monocultures, viral extracts from human stool, and human cord blood serum. Serving as the foundation of this study were standard approaches in mass spectrometry used in conjunction with three major quantitative proteomic techniques: (i) difference in-gel electrophoresis (DIGE), (ii) internal standards for absolute quantification of peptides (AQUA), and (iii) isobaric tags for relative and absolute quantification (iTRAQ). The work produced a novel rapid method allowing for the detection and phenotypic characterization of the dioxin-degrading bacterium Sphingomonas wittichii sp. RW1, and also provided an initial assessment of this bioremediation agent's proteomic response to selective culturing conditions, as revealed by two-dimensional (2D) DIGE and downstream mass spectrometry. A rapid method for the mass spectrometric detection of norovirus was also developed, an important pathogen implicated in diarrheal outbreaks worldwide. Subsequent work incorporated the AQUA approach to provide the methodological basis for quantitative surveillance of norovirus in human stool. Building upon experiences gained in the work with microbial proteomes, concluding efforts focused on the examination of human cord blood serum proteomes and the discovery of biomarkers modulated in the developing fetus in response to maternal cigarette smoking. This work furnished the first global assessment of the human umbilical cord serum proteome and the identification of seventeen candidate biomarkers in this readily accessible (i.e., easily and painlessly collected) diagnostic biofluid. Overall, this thesis served to illustrate potential strategies and benefits of applying qualitative and quantitative mass spectrometric techniques for the determination of protein biomarkers of public health importance.