Expression of 9-O- and 7,9-O-Acetyl Modified Sialic Acid in Cells and Their Effects on Influenza Viruses

Barnard, Karen N.; Wasik, Brian R.; LaClair, Justin R.; Buchholz, David W.; Weichert, Wendy S.; Alford-Lawrence, Brynn K.; Aguilar, Hector C.; Parrish, Colin R.

Here, we examine and more closely define the expression and distribution of 9-O-acetyl and 7,9-O-acetyl Sia on cells in culture, define the effects of SIAE and CasD1 on display of these Sia modifications, and perform an initial examination of the effects of these modified Sia on infection by IAV, IBV, ICV, and IDV. We used CRISPR-Cas9 for gene engineering of the enzymes that add or remove the 9-O-and 7,9-O-acetyl groups from Sia and combine these with the recently developed viral protein-derived probes that specifically recognize modified Sia. By merging these with high-pressure liquid chromatography (HPLC)-based quantification of the different Sia forms, we provide a more detailed understanding of the expression and localization of these modifications in cells and examine their effects on host-virus interactions as examples.