Processing of HA glycans in the distal Golgi complex shields HA from StRAb binding.

<p>(A and B) IAV PR8-infected MDCK cells were pulse-labeled with [³⁵S]-Met and chased at 37°C. At the end of each chase time point cells were detergent-lysed and then subjected to IP with the anti-HA head mAbs H17-L2 and H28-E23 (A) or the StRAbs C179 and 1F02 (B) at 4°C. Immunocollected HA species were analyzed by non-reducing SDS-PAGE and fluorography. pHA: processed, glycosylated HA. (C) Detergent extracts from [³⁵S]-Met-labeled and chased MDCK cells infected with IAV PR8 were treated with an irrelevant mAb (10G-4 to the VSV N protein; no depletion) or HA-depleted with the mAbs H28-E23 (control), C179, and 1F02 at 4°C as described in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004204#ppat-1004204-g001" target="_blank">Fig. 1A</a> before being incubated with H17-L2 also at 4°C in a second round of IP. Precipitated HA species were visualized by SDS-PAGE under non-reducing conditions and fluorography.