# AG1478 Elicits a Novel Anti-Influenza Function via an EGFR-Independent, GBF1-Dependent Pathway
## 1 Introduction  
Influenza infection is among the 10 leading causes of death in the United States and its occasional pandemics kill millions of people around the world. The major preventive measure against influenza infection is through vaccination [1]. However, due to the lengthy manufacturing process, seasonal flu vaccines have to be prepared months before the start of a flu season. Thus, a significant amount of guesswork will be required to estimate potential flu strains that may hit the United States. Furthermore, vaccination is not suitable for everyone. Children younger than 6 months old cannot get a flu vaccine as they are not able to develop a sufficient immune response. Other people that are not suitable for vaccination include those who are allergic to components of the flu vaccine and past and present patients of Guillain-Barre Syndrome (a severe paralyzing illness) [2]. Beside vaccines, antiviral drugs are available to combat flu, and these include M2 channel blockers (e.g., adamantanes including amantadine and rimantadine), neuraminidase inhibitors (e.g., oseltamivir, peramivir, zanamivir), influenza cap dependent endonuclease inhibitor (e.g., baloxavir), and antibodies that neutralize neuraminidase (NA) or haemagglutinin (HA) [3]. However, potential risks of emerging drug resistance prevent their routine use. In fact, amantadines and rimantadines are not recommended for empiric treatment of seasonal influenza as almost all circulating strains demonstrate resistance tothese drugs [2]. Although neuraminidase inhibitors are not as prone to viral resistance as adamantanes, viruses containing the oseltamivir resistant mutation (H275Y) rapidly became the predominant seasonal H1N1 strain in 2007-2008 [4]. Thus, new treatments for influenza viral infection are urgently needed. The influenza virus belongs to the family of _Orthomyzoviridae_. They can be genetically divided into three groups: influenza A (IAV), B (IBV), and C (ICV) viruses [5]. Among all three groups, IAVs are the most virulent human pathogens and have the potential for severe endemics or pandemics [6]. IAV can be further classified into subtypes based on their two major surface antigens--HA and NA (e.g., H1N1) [5]. A typical influenza viral particle consists of a viral ribonucleoprotein (vRNP) core and a lipid envelope. The vRNP core contains 8 viral RNA segments, and each segment is associated with trimeric RNA polymerase (PB1 PB2 and PA) coated with multiple nucleoproteins (NPs) [5]. The lipid envelope contains two types of glycoproteins (HA and NA) and an M2 ion channel in the form of spikes [7]. Influenza virus enters the host cell by the binding of HAs to sialic acids, the sugars that are attached to a number of cellular membrane proteins [8; 9]. C-type lectin can also act as a secondary or co-receptor for influenza infection in macrophages [10]. After viral internalization by the receptor-mediated endocytosis, low endosomal pH activates the M2 proton channel, and the increased proton influx facilitates dissociation of vRNPs from M1 proteins and their subsequent release into the cytoplasm. The unique part of the influenza life cycle is its nucleocytoplasmic trafficking. In the absence of M1 binding, vRNPs are transported into the nucleus to initiate genome replication and mRNA transcription. Viral mRNAs are transported back into the cytoplasm along with cellular mRNAs for viral protein translation, while the newly assembled vRNPs are exported to the cytosol with the assistance of M1 and NEP proteins [5]. Eventually, these vRNPs and other viral proteins are concentrated underneath the cell membrane domains that are already enriched with viral surface proteins such as HA, NA, and M2, and then bud out of the cell surface and cleaved off by NA [5]. Airway epithelium is the first line of defense against respiratory influenza infection.