Stress granule-inducing eukaryotic translation initiation factor 4A inhibitors block influenza A virus replication

Abstract

Eukaryotic translation initiation factor 4A (eIF4A) is a helicase that facilitates assembly of the translation preinitiation complex by unwinding structured mRNA 5’ untranslated regions. Pateamine A (PatA) and silvestrol are natural products that disrupt eIF4A function and arrest translation, thereby triggering the formation of cytoplasmic aggregates of stalled preinitiation complexes known as stress granules (SGs). Here we examined the effects of eIF4A inhibition by PatA and silvestrol on influenza A virus (IAV) protein synthesis and replication in cell culture. Treatment of infected cells with either PatA or silvestrol at early times post-infection results in SG formation, arrest of viral protein synthesis and failure to replicate the viral genome. PatA, which irreversibly binds to eIF4A, sustained long-term blockade of IAV replication following drug withdrawal, and inhibited IAV replication at concentrations that had minimal cytotoxicity. By contrast, the antiviral effects of silvestrol were fully reversible; drug withdrawal caused rapid SG dissolution and resumption of viral protein synthesis. IAV inhibition by silvestrol was invariably associated with cytotoxicity. PatA blocked replication of genetically divergent IAV strains, suggesting common dependence on host eIF4A activity. This study demonstrates the feasibility of targeting core host protein synthesis machinery to prevent viral replication.IMPORTANCEInfluenza A virus (IAV) relies on cellular protein synthesis to decode viral messenger RNAs. Pateamine A and silvestrol are natural products that inactivate an essential protein synthesis protein known as eIF4A. Here we show that IAV is sensitive to these eIF4A inhibitor drugs. Treatment of infected cells with pateamine A or silvestrol prevented synthesis of viral proteins, viral genome replication and release of infectious virions. The irreversible eIF4A inhibitor pateamine A sustained long-term blockade of viral replication, whereas viral protein synthesis quickly resumed after silvestrol was removed from infected cells. Prolonged incubation of either infected or uninfected cells with these drugs induced the programmed cell death cascade called apoptosis. Our findings suggest that core components of the host protein synthesis machinery are viable targets for antiviral drug discovery. The most promising drug candidates should selectively block protein synthesis in infected cells without perturbing bystander uninfected cells.

Innate Immune Evasion by Human Respiratory RNA Viruses

“…Influenza virus infection is also negatively influenced by the triggers that induce stress granule formation [102,103]. Indeed, this virus also inhibits the formation of stress granules, and influenza virus encoded NS1 seems to play a major role in this [104].…”

Stress Granule Formation is One of the Early Antiviral Mechanisms for Host Cells Against Coxsackievirus B Infection

“…was detected by western blotting. (Slaine et al 2017;Amorim et al 2017). Our results showed that CVB3 infection did not affect the formation of Ars-induced SGs, but that the levels of p-eIF2a in CVB3infected cells treated with Ars were significantly increased, possibly due to a mechanism associated with prolonged treatment of Ars which promotes eIF2a phosphorylation.…”

Repurposing host-based therapeutics to control coronavirus and influenza virus

“…CoV uses capindependent cis-acting RNA internal ribosome entry site (IRES) elements with eIF4A for viral translation that can also be inhibited by silvestrol [83]. Interestingly, silvestrol exhibits a potent and modest ability to inhibit IFV-A infection in A549 cells and MDCK cells, respectively, but fails to inhibit viral infection in Vero cells [84]. The antiviral effect of silvestrol on IFV infection is reversible, where drug withdrawal results in rapid dissolution of stalled preinitiation complexes (stress granules) and resumption of viral protein synthesis.…”

“…The antiviral effect of silvestrol on IFV infection is reversible, where drug withdrawal results in rapid dissolution of stalled preinitiation complexes (stress granules) and resumption of viral protein synthesis. Inhibition of IFV-A by silvestrol is associated with cytotoxicity [84]. By contrast, pateamine A irreversibly binds to eIF4A to result in an extended blockade of IFV-A replication after drug withdrawal, and it inhibits IFV-A replication in all A549, MDCK and Vero cells with minimal cytotoxicity [84].…”

“…Inhibition of IFV-A by silvestrol is associated with cytotoxicity [84]. By contrast, pateamine A irreversibly binds to eIF4A to result in an extended blockade of IFV-A replication after drug withdrawal, and it inhibits IFV-A replication in all A549, MDCK and Vero cells with minimal cytotoxicity [84]. These findings indicate the eIF4A is a promising target for therapeutic development to inhibit viral translation and replication by agents, such as silvestrol and pateamine A.…”