Detection of Saliva by Immunoaffinity and Mass Spectrometry

The identification of saliva in genital area during a criminal investigation can be a critical component in the prosecution of a sexual assault in France, as non-consensual oral-genital intercourses have been considered as crimes since 2021.The development of highly specific methods for saliva detection is therefore crucial as the commonly employed screening methods lack specificity. Protein mass spectrometry has proven to be a sensitive and specific method but is particularly time consuming. A faster and more sensitive hybrid approach using automated immunoaffinity mass spectrometry (IP-LC-MS/MS) has been recently developed and has been found to be particularly performant for the detection of a seminal fluid protein (semenogelin), allowing a high-throughput seminal fluid identification in semen samples. Like semenogelin, specific salivary proteins such as histatin type 1, cystatin D or proline-rich proteins (PRPs) could be detected using this promising approach, which has never been tested on saliva samples. In collaboration with the Clinical Proteomics Platform and the Department of Reproductive Medicine of the University Hospital of Montpellier, we aim to develop a protocol for the detection of specific saliva proteins by IP-LC-MS/MS in sexual assault-type samples.