Rapid detection and accurate identification of toxic chemical exposure are of paramount importance to various industries and government sectors. The use of analytical techniques to identify chemical warfare agents (CWAs), G-series, HD and VX in a known exposed area is commonplace, but there are currently no efficient analytical techniques available to specifically identify human exposure. The recent use of CWAs against civilians in war-torn countries stresses the need to develop accurate methods of detection and identification of CWAs among civilians and military personnel. This study aimed to establish a proteomic map of human plasma exposed to different CWAs and to identify potential biomarkers that could be used for the detection of specific CWA exposure.
Whole plasma was exposed to individual CWAs and analysed via three distinct methods. Samples were subjected to liquid trypsin digestion and shotgun LC-MS/MS on two mass spectrometers, additionally utilising gas phase fractionation for enhanced proteome coverage. Exposed plasma was additionally analysed via 1D SDS-PAGE and two-dimensional difference gel electrophoresis (2D-DIGE) coupled with in-gel trypsin digestion and LC-MS/MS. Data analyses were performed using PEAKS Studio X bioinformatics software.
Analysis revealed several potential biomarkers that can differentiate exposed versus unexposed plasma for various CWAs. Analysis of human serum albumin revealed sites of O-isomethylphosphonylation, O-pinacolylmethylphosphonylation and various phosphonylations sites indicative of chemical agent activity. Phosphorylation sites were removed in CWAs exposed plasma samples. The highest number of observed post-translational modifications occurred in plasma exposed to mustard gas.
This work has revealed unique and novel modifications sites in human plasma exposed to CWAs. These sites are potential biomarkers that hold promise for enabling future rapid and accurate identification of human CWA exposure.