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The Rac1 inhibitor NSC23766 exerts anti-influenza virus properties by affecting the viral polymerase complex activity.

Dierkes R, Warnking K, Liedmann S, Seyer R, Ludwig S, Ehrhardt C - PLoS ONE (2014)

Bottom Line: The frequent emergence of new influenza viruses in the human population underlines the urgent need for antiviral therapeutics in addition to the preventative vaccination against the seasonal flu.Inhibition of Rac1 by NSC23766 resulted in impaired replication of a wide variety of influenza viruses, including a human virus strain of the pandemic from 2009 as well as highly pathogenic avian virus strains.Furthermore, we identified a crucial role of Rac1 for the activity of the viral polymerase complex.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Virology (IMV), Centre of Molecular Virology (ZMBE), Westfälische Wilhelms-University, Münster, Germany.

ABSTRACT
The frequent emergence of new influenza viruses in the human population underlines the urgent need for antiviral therapeutics in addition to the preventative vaccination against the seasonal flu. To circumvent the development of resistance, recent antiviral approaches target cellular proteins needed by the virus for efficient replication. We investigated the contribution of the small GTPase Rac1 to the replication of influenza viruses. Inhibition of Rac1 by NSC23766 resulted in impaired replication of a wide variety of influenza viruses, including a human virus strain of the pandemic from 2009 as well as highly pathogenic avian virus strains. Furthermore, we identified a crucial role of Rac1 for the activity of the viral polymerase complex. The antiviral potential of NSC23766 was confirmed in mouse experiments, identifying Rac1 as a new cellular target for therapeutic treatment of influenza virus infections.

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The siRNA mediated knockdown of Rac1 or Tiam1 leads to impaired viral replication.A549 cells were transfected with non-silencing control siRNA or siRNA against Rac1 (A) or Tiam1 (B) for 72 or 48 h, respectively. Thereafter, cells were infected with A/Puerto-Rico/8/34 rec. (moi = 0.01) for 24 h. Progeny virus yields were determined by plaque assays. Data represent means ± SD of three independent experiments including two biological samples. Statistical significance was evaluated by Student's t-test (* p<0.05; ** p<0.01). Efficient knockdown of Rac1 or Tiam1 was determined in Western blot analysis using specific antibodies against Rac1 or Tiam1, respectively. Detection of ERK2 served as a loading control.
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pone-0088520-g003: The siRNA mediated knockdown of Rac1 or Tiam1 leads to impaired viral replication.A549 cells were transfected with non-silencing control siRNA or siRNA against Rac1 (A) or Tiam1 (B) for 72 or 48 h, respectively. Thereafter, cells were infected with A/Puerto-Rico/8/34 rec. (moi = 0.01) for 24 h. Progeny virus yields were determined by plaque assays. Data represent means ± SD of three independent experiments including two biological samples. Statistical significance was evaluated by Student's t-test (* p<0.05; ** p<0.01). Efficient knockdown of Rac1 or Tiam1 was determined in Western blot analysis using specific antibodies against Rac1 or Tiam1, respectively. Detection of ERK2 served as a loading control.

Mentions: As stated above, NSC23766 exerts inhibitory effects on Rac1 by preventing its interaction with the GEFs Tiam1 and Trio. To verify the role of Rac1 during IV replication, siRNAs against Rac1 or Tiam1 were used (Fig. 3). The knockdown of Rac1 was most efficient 72 h after transfection (∼80%), while efficient downregulation of Tiam1 was already achieved 48 h post transfection (∼86%). Silencing the expression of Rac1 led to significantly reduced replication of A/Puerto-Rico/8/34 24 h p.i. (Fig. 3A). Likewise, knockdown of the upstream factor Tiam1 led to reduced viral titers (Fig. 3B). Taken together, these data confirm a supportive role of Rac1 for IV replication and underline the specificity of the antiviral activity of NSC23766.


The Rac1 inhibitor NSC23766 exerts anti-influenza virus properties by affecting the viral polymerase complex activity.

Dierkes R, Warnking K, Liedmann S, Seyer R, Ludwig S, Ehrhardt C - PLoS ONE (2014)

The siRNA mediated knockdown of Rac1 or Tiam1 leads to impaired viral replication.A549 cells were transfected with non-silencing control siRNA or siRNA against Rac1 (A) or Tiam1 (B) for 72 or 48 h, respectively. Thereafter, cells were infected with A/Puerto-Rico/8/34 rec. (moi = 0.01) for 24 h. Progeny virus yields were determined by plaque assays. Data represent means ± SD of three independent experiments including two biological samples. Statistical significance was evaluated by Student's t-test (* p<0.05; ** p<0.01). Efficient knockdown of Rac1 or Tiam1 was determined in Western blot analysis using specific antibodies against Rac1 or Tiam1, respectively. Detection of ERK2 served as a loading control.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921225&req=5

pone-0088520-g003: The siRNA mediated knockdown of Rac1 or Tiam1 leads to impaired viral replication.A549 cells were transfected with non-silencing control siRNA or siRNA against Rac1 (A) or Tiam1 (B) for 72 or 48 h, respectively. Thereafter, cells were infected with A/Puerto-Rico/8/34 rec. (moi = 0.01) for 24 h. Progeny virus yields were determined by plaque assays. Data represent means ± SD of three independent experiments including two biological samples. Statistical significance was evaluated by Student's t-test (* p<0.05; ** p<0.01). Efficient knockdown of Rac1 or Tiam1 was determined in Western blot analysis using specific antibodies against Rac1 or Tiam1, respectively. Detection of ERK2 served as a loading control.
Mentions: As stated above, NSC23766 exerts inhibitory effects on Rac1 by preventing its interaction with the GEFs Tiam1 and Trio. To verify the role of Rac1 during IV replication, siRNAs against Rac1 or Tiam1 were used (Fig. 3). The knockdown of Rac1 was most efficient 72 h after transfection (∼80%), while efficient downregulation of Tiam1 was already achieved 48 h post transfection (∼86%). Silencing the expression of Rac1 led to significantly reduced replication of A/Puerto-Rico/8/34 24 h p.i. (Fig. 3A). Likewise, knockdown of the upstream factor Tiam1 led to reduced viral titers (Fig. 3B). Taken together, these data confirm a supportive role of Rac1 for IV replication and underline the specificity of the antiviral activity of NSC23766.

Bottom Line: The frequent emergence of new influenza viruses in the human population underlines the urgent need for antiviral therapeutics in addition to the preventative vaccination against the seasonal flu.Inhibition of Rac1 by NSC23766 resulted in impaired replication of a wide variety of influenza viruses, including a human virus strain of the pandemic from 2009 as well as highly pathogenic avian virus strains.Furthermore, we identified a crucial role of Rac1 for the activity of the viral polymerase complex.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Virology (IMV), Centre of Molecular Virology (ZMBE), Westfälische Wilhelms-University, Münster, Germany.

ABSTRACT
The frequent emergence of new influenza viruses in the human population underlines the urgent need for antiviral therapeutics in addition to the preventative vaccination against the seasonal flu. To circumvent the development of resistance, recent antiviral approaches target cellular proteins needed by the virus for efficient replication. We investigated the contribution of the small GTPase Rac1 to the replication of influenza viruses. Inhibition of Rac1 by NSC23766 resulted in impaired replication of a wide variety of influenza viruses, including a human virus strain of the pandemic from 2009 as well as highly pathogenic avian virus strains. Furthermore, we identified a crucial role of Rac1 for the activity of the viral polymerase complex. The antiviral potential of NSC23766 was confirmed in mouse experiments, identifying Rac1 as a new cellular target for therapeutic treatment of influenza virus infections.

Show MeSH
Related in: MedlinePlus