The Use of Saliva as a Biosample in the Light of COVID-19

Saliva is easy to collect and a biofluid that is readily available without the need for special equipment for its collection. The collection process, which is non-invasive and inexpensive, leads to obtaining a biomaterial that can serve as a source of information for molecular diagnostics of diseases in general medicine, genetics and dentistry. Unfortunately, many of the salivary methodologies are lacking important parameters to provide for not only the safety of the operator, but also the quality and reproducibility of the research. Since the COVID-19 pandemic, salivary diagnostics demonstrate a great potential for research of SARS-CoV 2. In this review, good practice for unstimulated saliva collection and patient preparation was provided, based on the latest literature and available guidelines. Schemes for saliva collection procedures were presented following an extended literature search. Descriptions of salivary probes/cups, techniques of saliva collection, and the use of specific buffering solutions for the stability of collected samples for SARS-CoV-2 detection were also evaluated.

A novel RT-LAMP workflow for rapid salivary diagnostics of COVID-19 and effects of age, gender and time from symptom onset

Objectives: Rapid diagnostics is pivotal to curb SARS-CoV-2 transmission, and saliva has emerged as a practical alternative to naso/oropharyngeal (NOP) specimens. We aimed to develop a direct RT-LAMP workflow for viral detection in saliva, and to provide more information regarding its potential in COVID-19 diagnostics. Methods: Clinical and contrived specimens were used to screen/optimize formulations and sample processing protocols. Salivary viral load was determined in symptomatic patients to evaluate clinical performance (n = 90) and to characterize saliva based on age, gender and time from onset of symptoms (n = 49). Results: The devised workflow achieved 93.2% sensitivity, 97% specificity, and 0.895 Kappa for salivas containing >102 copies/μL. Further analyses in saliva showed peak viral load in the first days of symptoms and lower viral loads in females, particularly among young individuals (<38 years). NOP RT-PCR data did not yield relevant associations. Conclusions: This novel saliva RT-LAMP workflow can be applied to point-of-care testing. This work reinforces that saliva better correlates with transmission dynamics than NOP specimens, and reveals gender differences that may reflect higher transmission by males. To maximize detection, testing should be done immediately after symptom onset, especially in females.

SALIVA AND SALIVAOMICS IN THE DIAGNOSIS OF ORAL AND SYSTEMIC DISEASES: A REVIEW

The quest for novel strategies in early disease detection and response to therapy is an essential ongoing process in health care setups.Along with other body fluids such as blood,mucus,urine,semen and vaginal fluids;saliva can also be considered for the detection of the disease.The Salivary diagnostics is a dynamic field that is being incorporated as part of disease diagnosis, clinical monitoring and for making important clinical decisions for patient care. This review presents the translational value of saliva as a credible clinical diagnostic biofluid in detection, early detection of the various diseases and response to treatment.

Exploring salivary diagnostics in COVID-19: a scoping review and research suggestions

Introduction Molecular diagnostics for SARS-CoV-2 infection characteristically involves the sampling of the throat or nasopharyngeal swab (NPS). However, these procedures are invasive, require necessary skills for sample collection, cause patient discomfort, and are non-conducive for extensive scale testing. Saliva is increasingly being suggested as an alternate diagnostic sample in SARS‐CoV‐2 infection. Objectives This scoping review was done with the objective of exploring the evidence on the role of saliva as an alternate diagnostic sample in SARS‐CoV‐2 condition. Methods Thorough search of the literature in major databases was undertaken in June 2020 using free text and MESH terms, followed by PRISMA to identify 17 studies for data extraction. Results and conclusions Evidence was summarised for study characteristics, salivary sampling characteristics, viral load, and longevity of virus in saliva. The literature supports that saliva offers a simple sample collection method compared to technique-sensitive NPS and has the advantage of point-of-care testing for initial screening in community or hospital-based set-up. The additional highlights of this review are heterogeneity in the current literature and the gaps in methodology. Therefore, a robust study design to generate higher levels of evidence has been proposed.

Salivary diagnosis of oral cancers by salivary samples: a systematic literature review

The aim of this article is to carry out a systematic analysis of the literature concerning the diagnosis of oral cancers by salivary samples. Different biomarkers, produced by the tumor itself or by its environment, show significant variations in their concentration at the salivary level, correlated or not at the blood or tissue level. After studying 239 articles, we included 36 in this analysis. This allowed us to extract 46 potential molecules for salivary diagnostics. Only 26 demonstrated a good level of evidence. 8 clusters have also been proposed for better specificity and sensitivity. To date, the protocols of the studies carried out do not allow to affirm that one or more biomarkers are effective for a salivary diagnosis of oral cancers. Part of the results contradict or sometimes lack precision. In addition, the studies included here do not have a good methodological quality and do not always take into account other factors influencing the concentrations (systemic diseases, age, sex, tobacco, alcohol, etc.). Additional studies are still necessary, notably with larger groups of patients, representative of the general population and standardization of the protocols for the study and quantification of biomarkers.

Salivary Metabolic Profiling of Systemic Disorders and Oral Neoplastic and Preneoplastic Conditions- A Narrative Review

Salivary metabolic profiling has emerged as an important mode of analysing the metabolic markers that aids in early disease detection in various systemic diseases. The metabolomics study states that, the transitional and the end products of interactions that take place between genes, proteins, and the environment are found to be involved in various disease processes. Salivary metabolomics stands as a highly specific and sensitive method in diagnosis of various conditions making it a better alternative to the conventional serum and tissue-based methods well. These metabolomics studies incorporate various analytical technologies for identifying each component that could be used as a biomarker. Hence, we reviewed the current state of salivary metabolomics, diagnostic efficiency and its associated technologies and its future role in identification and monitoring the disease prognosis. The study selection was done by locating those research papers that provided information on salivary diagnostics using metabolic markers for early diagnosis in systemic disorders, neoplastic and preneoplastic conditions with help of search engines like Pubmed, Google Scholar, Web of Science and Cochrane library. The results of each study were critically evaluated to accentuate the principal role played by these biomarkers in the field of salivary diagnostics.