Detection of Saliva by Immunoaffinity and Mass Spectrometry

Study Overview
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Brief Summary
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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.

Detailed Description
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Each participant will be contacted by a phone call the day before the visit, to present for a presentation of the study.The day of the visit, two types of samples will be collected : Saliva samples: on healthy volunteers in the Department of Legal Medicine (2 samples of 1.5 - 2 mL are collected for each volunteer). Vaginal samples : on women consulting in the Department of Reproductive Medicine (2 dry swabs on each patient). 2 groups, One group with vaginal secretion fluid samples only, and one group with vaginal secretion fluid + sperm samples.

Official Title
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Detection of Specific Salivary Proteins by Immunoaffinity and Mass Spectrometry

Conditions
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Sexual Assault

Intervention / Treatment
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* Other: Saliva collection
* Other: Vaginal secretion collection
* Other: IP-LC-MS/MS : immunoprecipitation enrichment with liquid chromatography coupled to tandem mass spectrometry


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Saliva Samples Men and women aged 18 or more Vaginal samples : Women aged 18 or more No unprotected vaginal sexual intercourse during the 10 days prior to the visit (group 1) Unprotected vaginal sexual intercourse with ejaculation in the 24 hours prior to the visit (group 2) Exclusion Criteria: Saliva Samples : Active pathology of the saliva glands (infection, tumor) Unprotected oral-genital sexual intercourse in the 24 hours prior to the visit Failure to obtain written informed consent after a reflection period Pregnant or breast feeding women Adult protected by law or under guardianship or curatorship No affiliation to the French Social Security System or no benefit from such a system Vaginal Samples : Oral-genital sexual intercourse (cunnilingus) in the 24 hours prior to the visit Failure to obtain written informed consent after a reflection period Pregnant or Breastfeeding women Adult protected by law or under guardianship or curatorship No affiliation to the French Social Security System or no benefit from such a system

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Saliva<br>Collection of two saliva samples (approx. 1.5 to 2 mL each) by passive drooling in healthy volunteers These samples will be centrifuged and the supernatant collected. | Other: Saliva collection<br>* Collection of 2 samples of 1.5 to 2mL of saliva by passive salivation in healthy volunteers<br>Other: IP-LC-MS/MS : immunoprecipitation enrichment with liquid chromatography coupled to tandem mass spectrometry<br>* sample preparation and analysis : Impregnation of the tips (absorbent cotton) of sterile dry swabs and vaginal swabs with controlled quantities of saliva. Immunocapture of salivary proteins of interest (histatin type 1, cystatin D, PRPs) by protein A affinity purification LC-MS/MS analysis of eluted purified peptides (Multiple Reaction Monitoring mode) Dilutions will be made from 10 to 10 (1/10, 1/100, 1/1000...), then after reaching a detectability threshold, specified by a second more precise analysis (e.g. if no signal at 1/1000, analysis at 1/500 then 1/250 etc.). Analytical sensitivity will be tested on three samples of each type (salivary, vaginal, vaginal + semen) to ensure reproducibility of results. Operators, unaware of the presence of saliva in the samples, will then carry out saliva-specific protein detection analysis using the IP-LC-MS/MS method.<br>|
| Other: Vaginal secretions<br>In order to be as close as possible to real life, two vaginal swabs (introduced through the vaginal orifice over a length of 2 to 3 cm) will be taken with a sterile dry swab during the gynecological examination (prior to endovaginal ultrasound or any other endovaginal procedure) of patients included in the Reproductive Medicine Service. | Other: Vaginal secretion collection<br>* Collection of vaginal secretions with 2 dry swabs in women<br>Other: IP-LC-MS/MS : immunoprecipitation enrichment with liquid chromatography coupled to tandem mass spectrometry<br>* sample preparation and analysis : Impregnation of the tips (absorbent cotton) of sterile dry swabs and vaginal swabs with controlled quantities of saliva. Immunocapture of salivary proteins of interest (histatin type 1, cystatin D, PRPs) by protein A affinity purification LC-MS/MS analysis of eluted purified peptides (Multiple Reaction Monitoring mode) Dilutions will be made from 10 to 10 (1/10, 1/100, 1/1000...), then after reaching a detectability threshold, specified by a second more precise analysis (e.g. if no signal at 1/1000, analysis at 1/500 then 1/250 etc.). Analytical sensitivity will be tested on three samples of each type (salivary, vaginal, vaginal + semen) to ensure reproducibility of results. Operators, unaware of the presence of saliva in the samples, will then carry out saliva-specific protein detection analysis using the IP-LC-MS/MS method.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Reproducibility between saliva samples | Intra-assessor agreement on saliva samples, which involves testing the first sample and retesting the second sample The study's primary endpoint will be to measure the reliability of the protocol, consisting of reproducibility or intra-assessor agreement,for the detection of specific salivary proteins (histatin type 1, PRPs, cystatin D) using the IP-LC-MS/MS method on adult saliva samples. Intra-assessor agreement (test/retest) will be measured by their means +/- standard deviation. Several analyses (between 3 or 4) on the same sample will be carried out to determine whether the results are identical | 3 months | 
| Intermediate fidelity between technicians on saliva samples | Inter-assessor agreement(Cohen's kappa coefficient) on saliva samples, which involves testing several samples by at least 2 different technicians The study's primary endpoint will be to measure the reliability of the protocol, consisting of intermediate fidelity or inter-assessor agreement (Cohen's kappa coefficient) for the detection of specific salivary proteins (histatin type 1, PRPs, cystatin D) using the IP-LC-MS/MS method on adult saliva samples. The kappa coefficient gives a score ranging from 0 to 1. If the coders totally agree, κ = 1. If they totally disagree (or agree due solely to chance), κ ≤ 0. | 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Reproducibility between vaginal samples soaked with saliva | Intra-assessor agreement on vaginal samples soaked with saliva The secondary endpoints, will consist of repeating the primary endpoints (i.e. reproducibility and intermediate fidelity) on the vaginal samples impregnated with sperm or not. Again, the same sample will be tested several times (between 3 or 4) to see if the results come back similar. | 3 months | 
| Intermediate fidelity between technicians on vaginal samples soaked with saliva | : Inter-assessor agreement (Cohen's kappa coefficient) on vaginal samples soaked with saliva The secondary endpoints, will consist of repeating the primary endpoints (i.e. reproducibility and intermediate fidelity) on the vaginal samples impregnated with sperm or not. The kappa coefficient gives a score ranging from 0 to 1. If the coders totally agree, κ = 1. If they totally disagree (or agree due solely to chance), κ ≤ 0. | 3 months | 
| Analytical Sensibility | Lowest saliva concentration (µL) detected by the method on saliva samples and on vaginal samples soaked with saliva in controlled condition | 3 months | 
| Diagnostic sensibility | Analysis of saliva samples and vaginal samples soaked with saliva in controlled condition, to determine the rate of detection of true positives and false negatives | 3 months | 
| Diagnostic specificity | Analysis of vaginal samples and dry samples in controlled condition, to determine the rate of false positives and true negatives. | 3 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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saliva, proteins, biomarkers, mass spectrometry