Host Lipid Rafts Play a Major Role in Binding and Endocytosis of Influenza A Virus

Abstract

Influenza still remains one of the most challenging diseases, posing a significant threat to public health. Host lipid rafts play a critical role in influenza A virus (IAV) assembly and budding, however, their role in polyvalent IAV host binding and endocytosis had remained elusive until now. In the present study, we observed co-localization of IAV with a lipid raft marker ganglioside, GM1, on the host surface. Further, we isolated the lipid raft micro-domains from IAV infected cells and detected IAV protein in the raft fraction. Finally, raft disruption using Methyl-β-Cyclodextrin revealed significant reduction in IAV host binding, suggesting utilization of host rafts for polyvalent binding on the host cell surface. In addition to this, cyclodextrin mediated inhibition of raft-dependent endocytosis showed significantly reduced IAV internalization. Interestingly, exposure of cells to cyclodextrin two hours post-IAV binding showed no such reduction in IAV entry, indicating use of raft-dependent endocytosis for host entry. In summary, this study demonstrates that host lipid rafts are selected by IAV as a host attachment factors for multivalent binding, and IAV utilizes these micro-domains to exploit raft-dependent endocytosis for host internalization, a virus entry route previously unknown for IAV.

Structural and molecular modelling studies reveal a new mechanism of action of chloroquine and hydroxychloroquine against SARS-CoV-2 infection

“…Sialic acids linked to glycoproteins and gangliosides are used by a broad range of viruses as receptors and/or attachment factors for cell entry [10] . These viruses include major human pathogens affecting the respiratory tract, such as influenza [21] and coronaviruses [22 , 23] . The attachment to sialic-acid-containing cell surface structures is mediated by receptor-binding proteins that belong to the viral spike.…”

Depletion of Host and Viral Sphingomyelin Impairs Influenza Virus Infection

“…Therefore, the membrane properties and integrity are important determinants of efficient infection. IAV has been shown to selectively bind to host membrane lipid rafts (Eierhoff et al, 2010;Verma et al, 2018). These specialized membrane microdomains are formed from the preferential association of cholesterol with sphingolipids (Zhang et al, 2009).…”

“…It is predominantly found in the outer leaflet of the plasma membrane, endomembranes, as well as in the intracellular organelles (Slotte, 2013). Depletion of host membrane cholesterol using Methyl-β-Cyclodextrin (MβCD) reduced IAV binding and internalization (Eierhoff et al, 2010;Verma et al, 2018). However, MβCD also depletes SM, whose effect on IAV binding and internalization has been overlooked.…”

Cyclodextrins: Emerging Medicines of the New Millennium

“…Particles of the influenza A virus, when treated with RAMEB for cholesterol depletion (Figure 2), exhibit disruption of lipid rafts, with consequent structural deformations of the viral membrane; microscopy examination allows observation of holes in the viral envelope [38]. Furthermore, cholesterol depletion by RAMEB significantly reduces the infectivity of viral particles of influenza A (H1N1 strain) in vitro [39,40]. Although RAMEB is not yet regulated for human use, these preliminary results have opened the way for the application of other cyclodextrins in the control of influenza infection in humans.…”