Covid-19 Pandemic, Glycobiology, Glycan Shields, Vaccine Strategies, Heparin Sulfate: A Mini Review

Abstract

The area of sugar biology (glycobiology) is an under-reported component of the Covid-19 pandemic. This minireview will provide non-experts with a brief overview of some aspects of glycobiology with emphasis on metabolic pathways and enzymes that are involved in the main topic of this review, the virus glycan shields of HIV and SARS-Cov-2 that help protect the viruses from immunological recognition. The HIV glycan shield is more dense than the SARS-Cov-2 shield and is one reason that a successful HIV vaccine has not yet been developed. The glycan shields of both HIV and SARS-Cov-2 consist of mannose chains and other sugars that resemble host molecules, explaining why they are not strongly recognized by the host's immune system as foreign. But because of the less dense SARS-Cov-2 glycan shield there is more optimism that an effective SARS-Cov-2 vaccine could be developed. This, in addition, to unusual vaccine approaches using, for example, virus messenger RNA instead of whole cells or viral proteins, and potential use of heparin sulfate to block virus attachment to cells are concepts that will be also discussed. This mini-review therefore begins with an overview of glycobiology to introduce the topic of viral glycan shields of HIV compared with SARS-COV-2. This is followed by discussion of novel vaccine approaches for SARS-COV-2 and the interesting issue of the glycan heparin sulfate that binds to the SARS-COV-2 surface and might be engineered to produce an anti-viral drug.