How bacteria utilize sialic acid during interactions with the host: snip, snatch, dispatch, match and attach

Area of Science:

• Microbiology
• Glycobiology
• Immunology

Background:

• Sialic acids, including N-glycolylneuraminic acid (Neu5Gc) and N-acetylneuraminic acid (Neu5Ac), are prevalent glycans in mammals.
• Humans uniquely express Neu5Ac due to a genetic mutation affecting Neu5Gc synthesis.
• Bacteria metabolize sialic acids as a nutrient source and employ sialidases to release them from host glycans.

Purpose of the Study:

• To review recent advances (5-10 years) in understanding sialic acid's role in bacteria-host interactions.
• To contextualize current findings with historical discoveries in the field.
• To focus on molecular mimicry, bacterial surface sialic acid incorporation, and sialic acid as a receptor for bacterial factors.

Main Methods:

• Literature review of recent scientific publications (last 5-10 years).
• Analysis of historical discoveries related to sialic acids and bacterial pathogenesis.
• Synthesis of information on bacterial sialidase activity, sialic acid metabolism, and molecular mimicry.

Main Results:

• Human-adapted pathogens preferentially utilize Neu5Ac, a 'human-specific' glycan.
• Bacteria employ sialidases for nutrient acquisition and immune system evasion.
• Pathogens engage in molecular mimicry by incorporating sialic acids into their surface structures (LOS, LPS, capsules) and using sialic acid-containing glycans as receptors for adhesins and toxins.

Conclusions:

• Sialic acid metabolism and mimicry are critical strategies for bacterial virulence and host adaptation.
• Understanding these mechanisms provides insights into host-pathogen dynamics and potential therapeutic targets.
• Recent research highlights the sophisticated ways bacteria exploit host glycans for colonization and pathogenesis.