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The Robust Restriction of Zika Virus by Type-I Interferon in A549 Cells Varies by Viral Lineage and Is Not Determined by IFITM3.

ABSTRACT: Type-I interferon (IFN-I) is a major antiviral host response but its impact on Zika virus (ZIKV) replication is not well defined, particularly as it relates to different circulating strains. Interferon stimulated genes (ISGs) that inhibit ZIKV, such as IFITM3, have been identified largely using overexpression studies. Here, we tested whether diverse ZIKV strains differed in their susceptibility to IFN-I-mediated restriction and the contribution of IFITM3 to this restriction. We identified a robust IFN-I-mediated antiviral effect on ZIKV replication (>100-fold reduction) in A549 cells, a commonly used cell line to study ZIKV replication. The extent of inhibition depended on the IFN-I type and the virus strain tested. Viruses from the American pathogenic outbreak were more sensitive to IFN? (p = 0.049) and IFN? (p = 0.09) than African-lineage strains, which have not been linked to severe pathogenesis. Knocking out IFITM3 expression did not dampen the IFN-I antiviral effect and only high overexpression of IFITM3 led to ZIKV inhibition. Moreover, IFITM3 expression levels in different cells were not associated with IFN-mediated ZIKV inhibition. Taken together, our findings indicate that there is a robust IFN-I-mediated antiviral effect on ZIKV infection, particularly for American viruses, that is not due to IFITM3. A549 cells, which are a commonly used cell line to study ZIKV replication, present an opportunity for the discovery of novel antiviral ISGs against ZIKV.

SUBMITTER: Gobillot TA

PROVIDER: S-EPMC7290589 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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The Robust Restriction of Zika Virus by Type-I Interferon in A549 Cells Varies by Viral Lineage and Is Not Determined by IFITM3.

Gobillot Theodore A TA Humes Daryl D Sharma Amit A Kikawa Caroline C Overbaugh Julie J

Viruses 20200502 5

Type-I interferon (IFN-I) is a major antiviral host response but its impact on Zika virus (ZIKV) replication is not well defined, particularly as it relates to different circulating strains. Interferon stimulated genes (ISGs) that inhibit ZIKV, such as IFITM3, have been identified largely using overexpression studies. Here, we tested whether diverse ZIKV strains differed in their susceptibility to IFN-I-mediated restriction and the contribution of IFITM3 to this restriction. We identified a robu ...[more]

PMID: 32370187

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Project description:UnlabelledThe interferon-induced transmembrane protein (IFITM) family of proteins inhibit infection of several different enveloped viruses in cell culture by virtue of their ability to restrict entry and fusion from late endosomes. As few studies have evaluated the importance of Ifitm3 in vivo in restricting viral pathogenesis, we investigated its significance as an antiviral gene against West Nile virus (WNV), an encephalitic flavivirus, in cells and mice. Ifitm3(-/-) mice were more vulnerable to lethal WNV infection, and this was associated with greater virus accumulation in peripheral organs and central nervous system tissues. As no difference in viral burden in the brain or spinal cord was observed after direct intracranial inoculation, Ifitm3 likely functions as an antiviral protein in nonneuronal cells. Consistent with this, Ifitm3(-/-) fibroblasts but not dendritic cells resulted in higher yields of WNV in multistep growth analyses. Moreover, transcomplementation experiments showed that Ifitm3 inhibited WNV infection independently of Ifitm1, Ifitm2, Ifitm5, and Ifitm6. Beyond a direct effect on viral infection in cells, analysis of the immune response in WNV-infected Ifitm3(-/-) mice showed decreases in the total number of B cells, CD4(+) T cells, and antigen-specific CD8(+) T cells. Finally, bone marrow chimera experiments demonstrated that Ifitm3 functioned in both radioresistant and radiosensitive cells, as higher levels of WNV were observed in the brain only when Ifitm3 was absent from both compartments. Our analyses suggest that Ifitm3 restricts WNV pathogenesis likely through multiple mechanisms, including the direct control of infection in subsets of cells.ImportanceAs part of the mammalian host response to viral infections, hundreds of interferon-stimulated genes (ISGs) are induced. The inhibitory activity of individual ISGs varies depending on the specific cell type and viral pathogen. Among ISGs, the genes encoding interferon-induced transmembrane protein (IFITM) have been reported to inhibit multiple families of viruses in cell culture. However, few reports have evaluated the impact of IFITM genes on viral pathogenesis in vivo In this study, we characterized the antiviral activity of Ifitm3 against West Nile virus (WNV), an encephalitic flavivirus, using mice with a targeted gene deletion of Ifitm3 Based on extensive virological and immunological analyses, we determined that Ifitm3 protects mice from WNV-induced mortality by restricting virus accumulation in peripheral organs and, subsequently, in central nervous system tissues. Our data suggest that Ifitm3 restricts WNV pathogenesis by multiple mechanisms and functions in part by controlling infection in different cell types.

Project description:Interferon-induced transmembrane protein 3 (IFITM3) is a cellular factor that reduces HIV-1 infectivity by an incompletely understood mechanism. We show here that viruses differing only in the envelope glycoprotein (Env) expressed on their surface have different sensitivities to IFITM3. Measurements of the sensitivity of viruses to neutralizing antibodies showed that IFITM3 increased the sensitivity of IFITM3-sensitive viruses to PG16, which targets the V1V2 loop, suggesting that IFITM3 promotes exposure of the PG16 epitope of IFITM3-sensitive viruses. Exchanges of V1V2 loops between the Env proteins of sensitive and resistant viruses revealed that V1V2 and V3 act together to modulate viral sensitivity to IFITM3. Co-immunoprecipitation experiments showed that IFITM3 interacted with both the precursor (gp160) and cleaved (gp120) forms of Env from IFITM3-sensitive viruses, but only with the precursor (gp160) form of Env from IFITM3-resistant viruses. This finding suggests that the interaction between the Env of resistant viruses and IFITM3 was inhibited once Env had been processed in the Golgi apparatus. This hypothesis was supported by immunofluorescence experiments, which showed a strong colocalization of IFITM3 with the Env of sensitive viruses, but only weak colocalization with the Env of resistant viruses on the plasma membrane of virus-producing cells. Together, these results indicate that IFITM3 interacts with Env, inducing conformational changes that may decrease viral infectivity. This antiviral action is, nevertheless, modulated by the nature of the Env, in particular its V1V2 and V3 loops, which after maturation may be able to escape this interaction.IMPORTANCE Interferon-induced transmembrane protein 3 (IFITM3) is a cellular factor that reduces HIV-1 infectivity by an incompletely understood mechanism. This study aimed to elucidate the role of the HIV-1 envelope glycoprotein (Env) in determining viral susceptibility to IFITM3. We found that viruses differing only in Env expressed on their surface had different sensitivities to IFITM3. By comparing the Env proteins of viruses that were highly sensitive or resistant to IFITM3, we obtained new insight in the mechanisms by which HIV-1 escapes this protein. We showed that IFITM3 interacts with the Env protein of sensitive viruses in virion-producing cells, inducing conformational changes that may decrease viral infectivity. However, this antiviral action is modulated by the nature of Env, particularly the V1V2 and V3 loops, which may be able to escape this interaction after processing in the Golgi.

Dataset Information

The Robust Restriction of Zika Virus by Type-I Interferon in A549 Cells Varies by Viral Lineage and Is Not Determined by IFITM3.

Publications

The Robust Restriction of Zika Virus by Type-I Interferon in A549 Cells Varies by Viral Lineage and Is Not Determined by IFITM3.

Similar Datasets

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