AbstractsMedical & Health Science

For infectious diseases and cancers, currently there is no ideal diagnostic method. I present here an iMALDI assay that holds the promise as the future platform of clinical diagnostics. It uses immobilized anti-peptide antibodies and MALDI-MS to detect and quantify protein expression and modification levels. By determining peptide MW with MS and sequence with MS/MS, the iMALDI assay is highly sensitive and nearly absolutely specific. Furthermore, this technology is safe and capable of absolute quantitation, multipexing and high-throughput analysis. The iMALDI-based diagnostics has been developed for Francisella tularensis (F. tularensis), an infectious bacterium, and the epidermal growth factor receptor (EGFR), a marker for several cancers. F. tularensis has been designated as one of the ten organisms most likely to be engineered for bioterrorism. Methods for early and specific diagnosis are of critical importance. The F. tularensis iMALDI assay provides unambiguous detection of F. tularensis peptides at attomole levels from peptide solutions, and at low CFU levels from bacteria. It allows absolute quantitation of the F. tularensis target peptide and therefore the parent protein. It is able to provide absolute specificity, avoiding false positives from the non-specific binding. The assay is also applied to samples that are more useful for screening large populations, such as nasal swabs and urine. It is also safe. EGFR is highly expressed in a variety of tumors, and is therefore an important biomarker for cancer diagnosis and a target for cancer therapy. The EGFR iMALDI assay can detect EGFR in the low attomole range in buffer and in one mammalian breast cancer cells. It is highly specific. It also allows absolute quantitation of the target peptide and therefore the parent protein. This technique is capable of detecting EGFR in tumors. The iMALDI assay can be easily adapted to other target peptides and therefore has broad applications in clinical diagnosis and therapy selection of other pathogens and diseases.