# Microbial Recognition of Sialic Acid Diversity in the Oral Cavity

> **NIH NIH R01** · STATE UNIVERSITY OF NEW YORK AT BUFFALO · 2020 · $504,825

## Abstract

PROJECT SUMMARY
Sialic acids (Sias), the outermost termini of glycan chains decorating glycoproteins and glycolipids,
comprise a diverse family of nine-carbon sugar acids, where structural variants are defined by
substitutions at different carbon positions. Sias are involved in cell-cell recognition processes and
modulate a wide variety of physiological and pathological processes, including recognition by viruses
and other pathogenic microorganisms. On salivary glycoproteins, terminal Sias constitute important
cognate glycan motifs recognized by Sia-binding adhesins of oral commensal streptococci. This
recognition enables initial adhesion and colonization of saliva-coated oral surfaces by streptococci.
However, if these normally harmless commensal Sia-binding streptococci happen to transgress the
tissue barrier at the gingival margin and evade neutrophil defense, they can become dispersed within
the bloodstream and act as agents of systemic diseases, including infectious endocarditis. Because
Sias play a role in all of these events, the finer specificities of streptococcal binding to the various
subtypes of Sias become an important question to explore. Our group has recently performed a
comprehensive screening of clinical isolates of dental plaque streptococcal strains for their ability to
bind to different Sia subtypes. Through analyzing their finer Sia-subtype binding specificities using a
novel sialoglycan array, we found streptococci in the oral cavity of human individuals that bind to a
non-human sialic acid, N-glycolylneuraminic acid (Neu5Gc). This is significant because humans,
unlike most other mammals, are genetically unable to synthesize Neu5Gc. In this project, we aim to
determine the structural basis for differential recognition of Neu5Gc and Neu5Ac by these Sia-binding
streptococci, and to identify their natural receptors in the human oral cavity. We will investigate the
molecular basis of Sia-mediated streptococcal binding to salivary sialoglycoproteins. We will identify
other bacterial species in oral biofilms that express Sias on their surface and are targets for
interbacterial adhesion by Neu5Gc-binding streptococci. Lastly, we will determine the molecular basis
of Sia-mediated binding of streptococci to phagocytes and investigate the functional consequences of
streptococcal binding to different Sia-subtypes on bacterial uptake and phagocyte activation. Overall,
these studies are expected to break new ground by demonstrating how expression of Sia-subtypes
influences bacteria-host interactions in the human oral cavity. The knowledge gained will likely have
a positive impact on early diagnosis and prevention of dental, oral, and systemic diseases caused by
oral microbes.

## Key facts

- **NIH application ID:** 9964766
- **Project number:** 5R01DE019807-08
- **Recipient organization:** STATE UNIVERSITY OF NEW YORK AT BUFFALO
- **Principal Investigator:** Stefan Hans-Klaus Ruhl
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $504,825
- **Award type:** 5
- **Project period:** 2010-07-01 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9964766

## Citation

> US National Institutes of Health, RePORTER application 9964766, Microbial Recognition of Sialic Acid Diversity in the Oral Cavity (5R01DE019807-08). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9964766. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*