tetano
Editor, Senior Moderator
Viral Immunol. 2019 Mar 1. doi: 10.1089/vim.2018.0118. [Epub ahead of print]
[h=1]A Novel Role for PDZ-Binding Motif of Influenza A Virus Nonstructural Protein 1 in Regulation of Host Susceptibility to Postinfluenza Bacterial Superinfections.[/h] Shepardson K[SUP]1[/SUP], Larson K[SUP]1[/SUP], Cho H[SUP]1[/SUP], Johns LL[SUP]1[/SUP], Malkoc Z[SUP]1[/SUP], Stanek K[SUP]1[/SUP], Wellhman J[SUP]1[/SUP], Zaiser S[SUP]2[/SUP], Daggs-Olson J[SUP]2[/SUP], Moodie T[SUP]2[/SUP], Klonoski JM[SUP]2[/SUP], Huber VC[SUP]2[/SUP], Rynda-Apple A[SUP]1[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] Influenza A viruses (IAVs) have multiple mechanisms for altering the host immune response to aid in virus survival and propagation. While both type I and II interferons (IFNs) have been associated with increased bacterial superinfection (BSI) susceptibility, we found that in some cases type I IFNs can be beneficial for BSI outcome. Specifically, we have shown that antagonism of the type I IFN response during infection by some IAVs can lead to the development of deadly BSI. The nonstructural protein 1 (NS1) from IAV is well known for manipulating host type I IFN responses, but the viral proteins mediating BSI severity remain unknown. In this study, we demonstrate that the PDZ-binding motif (PDZ-bm) of the NS1 C-terminal region from mouse-adapted A/Puerto Rico/8/34-H1N1 (PR8) IAV dictates BSI susceptibility through regulation of IFN-α/β production. Deletion of the NS1 PDZ-bm from PR8 IAV (PR8-TRUNC) resulted in 100% survival and decreased bacterial burden in superinfected mice compared with 0% survival in mice superinfected after PR8 infection. This reduction in BSI susceptibility after infection with PR8-TRUNC was due to the presence of IFN-β, as protection from BSI was lost in Ifn-β[SUP]-/-[/SUP] mice, resembling BSI during PR8 infection. PDZ-bm in PR8-infected mice inhibited the production of IFN-β posttranscriptionally, and both delayed and reduced expression of the tunable interferon-stimulated genes. Finally, a similar lack of BSI susceptibility, due to the presence of IFN-β on day 7 post-IAV infection, was also observed after infection of mice with A/TX98-H3N2 virus that naturally lacks a PDZ-bm in NS1, indicating that this mechanism of BSI regulation by NS1 PDZ-bm may not be restricted to PR8 IAV. These results demonstrate that the NS1 C-terminal PDZ-bm, like the one present in PR8 IAV, is involved in controlling susceptibility to BSI through the regulation of IFN-β, providing new mechanisms for NS1-mediated manipulation of host immunity and BSI severity.
[h=4]KEYWORDS:[/h] NS1; antiviral immunity; bacterial superinfection; influenza; interferons
PMID: 30822217 DOI: 10.1089/vim.2018.0118
[h=1]A Novel Role for PDZ-Binding Motif of Influenza A Virus Nonstructural Protein 1 in Regulation of Host Susceptibility to Postinfluenza Bacterial Superinfections.[/h] Shepardson K[SUP]1[/SUP], Larson K[SUP]1[/SUP], Cho H[SUP]1[/SUP], Johns LL[SUP]1[/SUP], Malkoc Z[SUP]1[/SUP], Stanek K[SUP]1[/SUP], Wellhman J[SUP]1[/SUP], Zaiser S[SUP]2[/SUP], Daggs-Olson J[SUP]2[/SUP], Moodie T[SUP]2[/SUP], Klonoski JM[SUP]2[/SUP], Huber VC[SUP]2[/SUP], Rynda-Apple A[SUP]1[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] Influenza A viruses (IAVs) have multiple mechanisms for altering the host immune response to aid in virus survival and propagation. While both type I and II interferons (IFNs) have been associated with increased bacterial superinfection (BSI) susceptibility, we found that in some cases type I IFNs can be beneficial for BSI outcome. Specifically, we have shown that antagonism of the type I IFN response during infection by some IAVs can lead to the development of deadly BSI. The nonstructural protein 1 (NS1) from IAV is well known for manipulating host type I IFN responses, but the viral proteins mediating BSI severity remain unknown. In this study, we demonstrate that the PDZ-binding motif (PDZ-bm) of the NS1 C-terminal region from mouse-adapted A/Puerto Rico/8/34-H1N1 (PR8) IAV dictates BSI susceptibility through regulation of IFN-α/β production. Deletion of the NS1 PDZ-bm from PR8 IAV (PR8-TRUNC) resulted in 100% survival and decreased bacterial burden in superinfected mice compared with 0% survival in mice superinfected after PR8 infection. This reduction in BSI susceptibility after infection with PR8-TRUNC was due to the presence of IFN-β, as protection from BSI was lost in Ifn-β[SUP]-/-[/SUP] mice, resembling BSI during PR8 infection. PDZ-bm in PR8-infected mice inhibited the production of IFN-β posttranscriptionally, and both delayed and reduced expression of the tunable interferon-stimulated genes. Finally, a similar lack of BSI susceptibility, due to the presence of IFN-β on day 7 post-IAV infection, was also observed after infection of mice with A/TX98-H3N2 virus that naturally lacks a PDZ-bm in NS1, indicating that this mechanism of BSI regulation by NS1 PDZ-bm may not be restricted to PR8 IAV. These results demonstrate that the NS1 C-terminal PDZ-bm, like the one present in PR8 IAV, is involved in controlling susceptibility to BSI through the regulation of IFN-β, providing new mechanisms for NS1-mediated manipulation of host immunity and BSI severity.
[h=4]KEYWORDS:[/h] NS1; antiviral immunity; bacterial superinfection; influenza; interferons
PMID: 30822217 DOI: 10.1089/vim.2018.0118