Megan Stanifer, University of Florida

Zehra Sena Bumin1, Yağmur Keser1, Steeve Boulant1, Megan Stanifer1 1 Department of Molecular Genetics and Microbiology, University of Florida, College of Medicine, Gainesville, FL

Virus Replication: Entry, Exit and Everything in Between

Clathrin-mediated endocytosis is the most common pathway used by viruses to enter host cells. Following uptake by the clathrin machinery, viruses are delivered to the early endosome. Depending on the virus, they can escape from either the early endosome or continue within the endosomal pathway and escape from the late endosome or lysosome. We have previously shown that mammalian reovirus (MRV) enters by clathrin endocytosis and requires cathepsin processing in the late endosome to allow for its release into the cytosol.Previous studies have reported that key regulators of intrinsic immunity, interferon-stimulated genes (ISGs), play important roles in inhibiting viral entry. Three of these ISGs, LY6E, CD74, and NCOA7, have been shown to modulate the receptor-mediated entry and endosomal trafficking and maturation of several enveloped viruses. However, whether these ISGs can also control non-enveloped virus entry has not been evaluated. To explore the effect of LY6E, CD74, and NCOA7 in the entry of MRV in vitro, we generated LY6E, CD74, and NCOA7 overexpressing cell lines. We could show that overexpression of all three of these ISGs lead to a decrease in MRV infection but does not impact binding and entry. Importantly we could show that they acted on MRV entry as the activated form of MRV, known as an ISVP which does not require endosomal maturation, was not impacted by these ISGs. This is the first report showing that LY6E, CD74, and NCOA7 play a critical role in non-enveloped virus entry and release.