Comparing SARS-CoV-2 Viral Load in Human Saliva to Oropharyngeal Swabs, Nasopharyngeal Swabs, and Sputum: A Systematic Review and Meta-Analysis

A systematic review and meta-analysis were conducted to investigate the SARS-CoV-2 viral load in human saliva and compared it with the loads in oropharyngeal swabs, nasopharyngeal swabs, and sputum. In addition, the salivary viral loads of symptomatic and asymptomatic COVID-19 patients were compared. Searches were conducted using four electronic databases: PubMed, Embase, Scopus, and Web of Science, for studies published on SARS-CoV-2 loads expressed by CT values or copies/mL RNA. Three reviewers evaluated the included studies to confirm eligibility and assessed the risk of bias. A total of 37 studies were included. Mean CT values in saliva ranged from 21.5 to 39.6 and mean copies/mL RNA ranged from 1.91 × 101 to 6.98 × 1011. Meta-analysis revealed no significant differences in SARS-CoV-2 load in saliva compared to oropharyngeal swabs, nasopharyngeal swabs, and sputum. In addition, no significant differences were observed in the salivary viral load of symptomatic and asymptomatic COVID-19 patients. We conclude that saliva specimen can be used as an alternative for SARS-CoV-2 detection in oropharyngeal swabs, nasopharyngeal swabs, and sputum

A review on the role of salivary MUC5B in oral health

Background: The salivary glycoprotein MUC5B plays a versatile role in maintaining oral health. It contributes to lubrication, pellicle formation, antimicrobial defense, and water retention, and its glycans are an important nutrient for oral bacteria. This review aimed to describe the role of MUC5B in oral health and examine changes in its levels and composition in cases of hyposalivation and xerostomia. Highlight: In cases of hyposalivation, the reduction of total salivary MUC5B levels and MUC5B glycosylation patterns due to Sjögren's syndrome (SS) and medication intake appeared insignificantly limited. In patients with SS, xerostomia was related to reduced MUC5B levels at the anterior tongue. In cases of xerostomia, MUC5B glycosylation might be reduced, yet other factors such as total protein concentration, MUC7 levels and glycosylation, and salivary spinnbarkeit are involved. In contrast to SS- and medication-induced hyposalivation, radiotherapy in the head and neck region leads to a bona fide reduction in salivary MUC5B levels. Conclusion: Our findings suggest that MUC5B levels are clearly impaired in hyposalivation and xerostomia related to radiotherapy in the head and neck region versus those related to SS and medication intake. A reduction in glycosylation in the case of dry mouth appears associated with MUC5B and MUC7 as well as other factors

Identification and Characterization of MUC5B Binding Peptides by Phage Display

Objectives: MUC5B plays a multifactorial role in oral health. As a consequence, decreased MUC5B output leads to impaired salivary functions and xerostomia. Synthetic combinatorial technologies have been used to develop functional peptide libraries by phage display e.g. for therapeutic purposes. In this light, our primary aim was to identify peptide sequences with specific selectivity for salivary MUC5B in vitro using phage display. Our secondary aims were to analyze their effect on salivary spinnbarkeit in situ and their effect on acid-induced demineralization in vitro. Methods: MUC5B binding phages were selected by phage display. Peptide affinity to MUC5B was evaluated using MUC5B coated hydroxyapatite (HA) granules. The MUC5B binding peptides (MBPs) were then examined for their effects on salivary spinnbarkeit and protective effect on acid-induced demineralization in vitro. A competitive ELISA was performed to identify the binding epitope on MUC5B using F2, a MUC5B specific antibody. Results: MBP-12 and MBP-14 displayed the highest affinity to MUC5B. MBP-12 mildly stabilized the spinnbarkeit of serous saliva after overnight incubation and of mucous saliva at all timepoints tested. The addition of MBP-12 to a pellicle of unstimulated saliva on HA discs showed no additive protective effect against acid-induced demineralization. Epitope characterization suggested sulfo-Lewisa SO3–3Gal_1–3GlcNAc (galactose residue) as MBP-12 binding site on MUC5B. Conclusions: The use of phage display in generating MBPs was successful. Characterization of the MBPs revealed a mild effect on spinnbarkeit in case of mucous saliva. Possibly, combinatorial peptide libraries might contribute to the development of novel formulations to treat xerostomia