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.

Both 9-O-Ac and 7,9-O-Ac Sia are widely expressed within tissues and on mucosal surfaces of many animals, but with significant variation in the amounts present in different cells, tissues, and animals (10, 11). These modified Sia are present in secreted mucus on mucosal surfaces, including gastrointestinal and respiratory tissues, where they can potentially control many interactions with both normal flora and pathogens. However, there is still little known about the details of their display levels, cell association, and the ways in which their synthesis is regulated either in cells or on mucosal surfaces. While there have been suggestions that 9-O-and 7,9-O-Ac might influence IAV and IBV infection by interfering with HA binding or NA activities, direct evidence for their effects is sparse. In contrast, ICV and IDV are known to use 9-O-Ac as their primary receptor for cell binding and infection. Here, we use a number of new tools to define the cell-specific expression of 9-O-and 7,9-O-Ac and provide a preliminary test of their effects on IAV, IBV, ICV, and IDV infection.