Self-Interactions of a Virus Glycan Shield

Abstract

Viruses are able to infect cells because they possess a cell-surface component which enables them to bind on host cells, escape the surveillance of the immune system, and survive harsh environments. These physical properties on virus surface come from a coat or shield of carbohydrates present on it. These carbohydrates are attached to proteins embedded within the virus envelope or membrane. Current research in this field focuses on the chemical recognition of the sugars or proteins on the virus coat by receptors on host cells. Our goal is to interrogate the physical interactions of the virus coat in order to research broad-spectrum strategies that will disrupt the protection afforded by carbohydrate shield. The specific aim of the presented research is to test the propensity of sugar residues constituting the virus glycan shield to self-interact. The pseudovirus HIV pol- env- / VSV-G has a glycan shield that composed of mannose, galactose, sialic acid, and glucosamine. We synthesized gold nanoparticles coated with these sugars and tested the interaction with the pseudovirus. UV-VIS spectrophotometer results show that the plasmon resonance peak of the sugar-coated nanoparticles shifted in the presence of several of these sugars, but not in the presence of the control citrate-coated nanoparticles. The shift in colors is consistent with the coating on the nanoparticles being modified, possibly by binding to viruses. The UV studies were complemented by Dynamic Light Scattering studies which show a larger aggregate virus+nanoparticle species developing when there is a plasmon shift. AFM imaging was performed to deconstruct the structure of the aggregates. Preliminary results indicate that the sialic acid and mannobiose residues on the surface of a virus have a greater propensity for self-interactions, and may play a role in host-virus interaction since host cells are also abundant in these residues.