Protein‐Glycan Interactions: Binding of Different Norovirus VLPs to a Panel of Histo‐Blood Group Antigens

Abstract

Human noroviruses, highly contagious viruses are the major cause of most epidemic outbreaks of gastroenteritis.1 Our long-term goals are to develop point-of-care diagnostics for noroviruses; these are unavailable at the present time. PCR tests require trained personnel, equipment and are expensive. Antibody ELISAs tests are not very sensitive and are cross-reactive. There is a need to develop inexpensive, user-friendly rapid diagnostics for noroviruses. Noroviruses consist of five genogroups; genogroup GI, GII and GIV infect humans. The virion is composed of 90 dimers of a capsid protein VP1, which binds to human Histo-Blood Group Antigens (HBGAs).1 Therefore, we can detect noroviruses using HBGAs as capture molecules. However, the molecular level binding of noroviruses with HBGAs is not very well understood. As a first step towards our long-term goals of developing point-of-care diagnostics, we studied the interactions of VLPs (virus-like particles) with synthetic HBGAs. We used VLPs because noroviruses are difficult to grow in cell culture.2 Therefore, the protein was expressed in baculovirus, which spontaneously forms VLPs. 3 HBGAs are glycans that contain multiple carbohydrate moieties.4 In the ABH antigen system, there are four major types I–IV. We synthesized a panel of biotinylated synthetic ABH type I–IV glycans using chemical methods. The biotinylated glycans were attached to streptavidin coated sensor chips. These chips were used to study the binding affinities of VLPs from different genogroups using surface plasmon resonance (SPR). We used SPR because this is a highly sensitive label free system. Therefore, we do not have to label the VLPs; labeling VLPs may perturb the binding event. We found that VLPs from different genogroups bound with varying binding affinities to the synthetic glycans, suggesting that a library of glycans could be used in microarray format to yield a “fingerprint pattern of recognition” for each strain. The binding studies and the analysis of the biophysical studies will be the focus of this presentation. Support or Funding Information NIH (R01-AI089450) A panel of biotinylated bivalent HBGAs that have been reported as binding ligands for human noroviruses were synthesized using chemical methods. SPR studies show that VLPs from different genogroups bound with varying binding affinities to the synthetic glycans. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.