Neisseria meningitidis express numerous virulence factors that enable it to interact with diverse microenvironments within the host, during both asymptomatic nasopharyngeal colonization and invasive disease. On the host side, the receptors involved in these stages of infection are not fully elucidated, but are known to involve several carbohydrate structures (glycans).
In order to characterise the meningococcal glycointeractome, glycan arrays with 364 glycans representative of structures found on human cells, were used as a screening tool to investigate host glycans bound by N. meningitidis. The meningococcal wild-type strain MC58 bound to 223 glycans, including blood group antigens, mucins, gangliosides and glycosaminoglycans. Mutant strains lacking surface components, including capsule, lipooligosaccharide (LOS), Opc and pili, were investigated to identify the factors responsible for glycan binding. Surface plasmon resonance and isothermal calorimetry were used to confirm binding and determine affinities between surface components and host glycans. Different meningococcal LOS variants (whole cells and purified LOS) bound distinct glycans; the L3 LOS immunotype bound 26 structures, while L8 only bound 5 structures. We further demonstrated a direct glycan-glycan interaction between purified L3 LOS and Thomsen–Friedenreich (TF) antigen, with a KD of 13 nM. This is the highest affinity glycan-glycan interaction reported to date.
These findings highlight the diverse glycointeractions that may occur during different stages of meningococcal disease, which could be exploited for development of novel preventative and therapeutic strategies.