A comparison of influenza binding to erythrocytes from different animal species

Abstract

Introduction With the emergence of the H5N1 virus in humans that was of entirely avian origin, a better understanding of potential receptors of the influenza A virus is needed. It is widely accepted that terminally sialylated glycoconjugates on the surface of the red blood cells are receptors to which the influenza A virus binds to and causes the agglutination of red blood cells. By isolating glycans found on red blood cells, perhaps it is possible to find potential receptors that influenza A virus has preferential binding to.

There has been a general shift of using turkey red blood cells rather than chicken red blood cells for the haemagglutination of viruses over the past few decades. The influenza virus’s loss in ability to agglutinate chicken red blood cells but keep the ability to agglutinate turkey red blood cells a puzzling mystery. By comparing the differences, perhaps it is possible to elucidate structures influenza viruses prefer to bind to.

Methods Mass spectrometricanalysis of purified glycans will allow us to narrow down the structures of the most abundant glycans found on the erythrocyte surface. Lectin staining with flow cytometry is used to identify the receptor specificity of the influenza viruses. Haemagglutination assay in conjunction with glycan binding array data from the CFG will allow us to pinpoint the possible structures that give the viruses the ability to bind using treatments with sialidases.

Results The mass spectrometric data was good and the basic glycan structures were elucidated according to their mass to charge ratio. The proportion of the different glycans for each of the erythrocyte type was clearly shown. The lectin staining gave more accurate results have selecting a single cell population and it was clear that turkey red blood cells had more α2,3 and α2,6 linked glycans than the chicken red blood cells. The haemagglutination assay aided the identification of differentiating theα2,3 linked and α2,6 linked liking viruses. The glycan array binding data was obtained but some results were absent.

Conclusion It is certain that turkey red blood cells are better than chicken red blood cells for use in the haemagglutination assays as they present some glycans that are present in human bronchial epithelials. The most abundant sialylated glycan are the α2,6 linked sialylated glycans. The most abundant glycans on chicken red blood cells are either absent or in low abundance on the HBEs. Though the turkey red blood cells have some glycans that are present on HBEs, the glycan profile is very different. To agglutinate red blood cells, viruses are likely to bind to the bisecting glycans and shorter antennae glycans. In methodology: for lectin staining experiments, one must take caution in the lectin used as it may affect results. Sialidase S treated RBCs are a good method to distinguish α2,3 linked glycans liking viruses.