Nucleozin

Nucleozin Description:EC50: Nucleozin inhibited infection of MDCK cells by the viruses influenza A/WSN/33, H3N2 (clinical isolate) and Vietnam/1194/04 (H5N1) with an EC50 of 0.069±0.003 μM, 0.16±0.01 μM and 0.33±0.04 μM in PRA, respectively [1].
Influenza nucleoprotein is the most abundantly expressed protein during the course of infection with multiple functionalities. In the presence of nucleozin, a potent antagonist of NP accumulation in the nucleus, NP failed to enter the nucleus leading to the virus death [1].
In vitro: Nucleozin was found to effectively inhibite viral growth even when added within 6 h after inoculation of the MDCK cells with the virus, indicating that the antiviral activities of nucleozin reside on post-entry and post-nuclear events, suggesting that multiple processes involving NP may be affected, although only the nuclear import process of NP can be readily observed [1]. However, another in-vitro study demonstrated that the primary target of nucleozin was the viral ribonucleoprotein, not NP, and this work also provided proof of the principle that IAV replication can be effectively inhibited by blocking cytoplasmic trafficking of the viral genome [2].
In vivo: With respect to in vivo antiviral efficacy, mice treated with nucleozin had a considerably higher survival rate after inoculation by influenza A virus H5N1 strain A/Vietnam/1194/04 than untreated controls. Without any treatment, all mice had died 7 d after inoculation. In the nucleozin-treated group, 50% of those receiving two doses of nucleozin (100 μl of 2.3 mg/ml nucleozin) per day for 7 d survived for more than 21 d. The animal study results show that nucleozin protected mice against hypervirulent influenza A H5N1 virus in vivo and thus has the potential to be developed into useful anti-influenza therapeutics [1].
Clinical trial: Up to now, nucleozin is still in the preclinical development stage.
Reference:
[1] Kao RY, Yang D, Lau LS, Tsui WH, Hu L, Dai J, Chan MP, Chan CM, Wang P, Zheng BJ, Sun J, Huang JD, Madar J, Chen G, Chen H, Guan Y, Yuen KY. Identification of influenza A nucleoprotein as an antiviral target. Nat Biotechnol. 2010;28(6):600-5.
[2] Amorim MJ, Kao RY, Digard P. Nucleozin targets cytoplasmic trafficking of viral ribonucleoprotein-Rab11 complexes in influenza A virus infection. J Virol. 2013;87(8):4694-703.

Nucleozin targets cytoplasmic trafficking of viral ribonucleoprotein-Rab11 complexes in influenza A virus infection.[Pubmed:23408618]

J Virol. 2013 Apr;87(8):4694-703.

Novel antivirals are needed to supplement existing control strategies for influenza A virus (IAV). A promising new class of drug, exemplified by the compound Nucleozin, has recently been identified that targets the viral nucleoprotein (NP). These inhibitors are thought to act as "molecular staples" that stabilize interactions between NP monomers, promoting the formation of nonfunctional aggregates. Here we detail the inhibitory mechanism of Nucleozin, finding that the drug has both early- and late-acting effects on the IAV life cycle. When present at the start of infection, it inhibited viral RNA and protein synthesis. However, when added at later time points, it still potently blocked the production of infectious progeny but without affecting viral macromolecular synthesis. Instead, Nucleozin blocked the cytoplasmic trafficking of ribonucleoproteins (RNPs) that had undergone nuclear export, promoting the formation of large perinuclear aggregates of RNPs along with cellular Rab11. This effect led to the production of much reduced amounts of often markedly smaller virus particles. We conclude that the primary target of Nucleozin is the viral RNP, not NP, and this work also provides proof of the principle that IAV replication can be effectively inhibited by blocking cytoplasmic trafficking of the viral genome.

Structural Characterization of H1N1 Nucleoprotein-Nucleozin Binding Sites.[Pubmed:27404920]

Sci Rep. 2016 Jul 11;6:29684.

Influenza viruses are among the most common pathogens that threaten the health of humans and animals worldwide. Various anti-viral therapeutic agents are currently used for treatment and prophylaxis of influenza virus, but the targets of these drugs are easily mutated and result in resistance. Therefore, medications that have broad spectrum coverage are urgently needed to combat with the disease. Since nucleoprotein is regarded as a druggable target due to its conserved sequence and important functions during influenza virus life cycle, numerous studies are focused on this protein in attempts to develop broad-spectrum anti-influenza therapeutics. Recently, a novel small molecule compound, Nucleozin, was found to induce large aggregates of nucleoprotein, which in turn caused cessation of virus replication. However, the aggregation-inducing mechanism of Nucleozin has not been unveiled. Here we report the crystal structure of nucleoprotein-Nucleozin complex at 3 A resolution, which shows the binding sites of Nucleozin at nucleoprotein for the first time. The complex structure reveals how nucleoprotein and Nucleozin interact with each other and hence result in nucleoprotein aggregates. The structural information is envisaged to help accelerate the development of anti-influenza therapeutic agents.