Saliva Protein Profiling for Subject Identification

Subject identification, crucial to criminal investigations in Forensic Sciences, is in constant development due to technological advances. Generally, the identification of a perpetrator relies on trace amounts of DNA. However, sometimes the significantly low yield of DNA obtained from crime scenes and, in some cases, its degradation, prevents the generation of a reliable DNA profile suitable for subject identification. Proteins are deposited at crime scenes along with DNA and often at much higher concentrations than nucleic acids. As such, this pilot study tested the hypothesis whether salivary protein profiles could be used as fingermarks for subject identification in addition to or in lieu of DNA. Saliva samples were obtained from eleven volunteers, proteins were extracted and analyzed using tandem liquid-chromatography mass spectroscopy (LS-MS/MS). The protein functions were identified by using different publicly available and curated databases (e.g., STRING, DAVID, and Proteomicsdb). Protein profiles built with the most discriminating proteins allowed a clear separation of subjects, indicating that this approach has the potential to be used for lead generation and subject identification