Protective Effect of Flavonoids from Ohwia caudata against Influenza a Virus Infection

To identify new potential anti-influenza compounds, we isolated six flavonoids, 2′-hydroxyl yokovanol (1), 2′-hydroxyl neophellamuretin (2), yokovanol (3), swertisin (4), spinosin (5), and 7-methyl-apigenin-6-C-β-glucopyranosyl 2″-O-β-d-xylopyranoside (6) from MeOH extractions of Ohwia caudata. We screened these compounds for antiviral activity using green fluorescent protein (GFP)-expressing H1N1 (A/PR/8/34) influenza A-infected RAW 264.7 cells. Compounds 1 and 3 exhibited significant inhibitory effects against influenza A viral infection in co-treatment conditions. In addition, compounds 1 and 3 reduced viral protein levels, including M1, M2, HA, and neuraminidase (NA), and suppressed neuraminidase (NA) activity in RAW 264.7 cells. These findings demonstrated that 2′-hydroxyl yokovanol and yokovanol, isolated from O. caudate, inhibit influenza A virus by suppressing NA activity. The moderate inhibitory activities of these flavonoids against influenza A virus suggest that they may be developed as novel anti-influenza drugs in the future.

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Dicer is involved in protection against influenza A virus infection

Journal of General Virology ◽

10.1099/vir.0.83103-0 ◽

2007 ◽

Vol 88 (10) ◽

pp. 2627-2635 ◽

Cited By ~ 80

Author(s):

Alexey A. Matskevich ◽

Karin Moelling

Keyword(s):

Virus Infection ◽

Influenza A Virus ◽

Mammalian Cells ◽

Influenza A ◽

Virus Production ◽

Vero Cells ◽

Antiviral Response ◽

Protein Levels ◽

Infected Cells ◽

Influenza A Virus Infection

In mammals the interferon (IFN) system is a central innate antiviral defence mechanism, while the involvement of RNA interference (RNAi) in antiviral response against RNA viruses is uncertain. Here, we tested whether RNAi is involved in the antiviral response in mammalian cells. To investigate the role of RNAi in influenza A virus-infected cells in the absence of IFN, we used Vero cells that lack IFN-α and IFN-β genes. Our results demonstrate that knockdown of a key RNAi component, Dicer, led to a modest increase of virus production and accelerated apoptosis of influenza A virus-infected cells. These effects were much weaker in the presence of IFN. The results also show that in both Vero cells and the IFN-producing alveolar epithelial A549 cell line influenza A virus targets Dicer at mRNA and protein levels. Thus, RNAi is involved in antiviral response, and Dicer is important for protection against influenza A virus infection.

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Several protein regions contribute to determine the nuclear and cytoplasmic localization of the influenza A virus nucleoprotein

Microbiology ◽

10.1099/0022-1317-81-1-135 ◽

2000 ◽

Vol 81 (1) ◽

pp. 135-142 ◽

Cited By ~ 46

Author(s):

Rosario Bullido ◽

Paulino Gómez-Puertas ◽

Carmen Albo ◽

Agustín Portela

Keyword(s):

Influenza A Virus ◽

Influenza A ◽

Fluorescent Protein ◽

Intracellular Localization ◽

Phosphorylation Site ◽

Nuclear Accumulation ◽

Systematic Analysis ◽

Ribonucleoprotein Complexes ◽

Cytoplasmic Transport ◽

Green Fluorescent

A systematic analysis was carried out to identify the amino acid signals that regulate the nucleo-cytoplasmic transport of the influenza A virus nucleoprotein (NP). The analysis involved determining the intracellular localization of eight deleted recombinant NP proteins and 14 chimeric proteins containing the green fluorescent protein fused to different NP fragments. In addition, the subcellular distribution of NP derivatives that contained specific substitutions at serine-3, which is the major phosphorylation site of the A/Victoria/3/75 NP, were analysed. From the results obtained, it is concluded that the NP contains three signals involved in nuclear accumulation and two regions that cause cytoplasmic accumulation of the fusion proteins. One of the karyophilic signals was located at the N terminus of the protein, and the data obtained suggest that the functionality of this signal can be modified by phosphorylation at serine-3. These findings are discussed in the context of the transport of influenza virus ribonucleoprotein complexes into and out of the nucleus.

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Characterization of a Neuraminidase-Deficient Influenza A Virus as a Potential Gene Delivery Vector and a Live Vaccine

Journal of Virology ◽

10.1128/jvi.78.6.3083-3088.2004 ◽

2004 ◽

Vol 78 (6) ◽

pp. 3083-3088 ◽

Cited By ~ 50

Author(s):

Kyoko Shinya ◽

Yutaka Fujii ◽

Hiroshi Ito ◽

Toshihiro Ito ◽

Yoshihiro Kawaoka

Keyword(s):

Influenza Virus ◽

Influenza A Virus ◽

Influenza A ◽

Fluorescent Protein ◽

Cultured Cells ◽

Mutant Cell ◽

Wild Type Virus ◽

Reading Frame ◽

Foreign Genes ◽

Green Fluorescent

ABSTRACT We recently identified a packaging signal in the neuraminidase (NA) viral RNA (vRNA) segment of an influenza A virus, allowing us to produce a mutant virus [GFP(NA)-Flu] that lacks most of the NA open reading frame but contains instead the gene encoding green fluorescent protein (GFP). To exploit the expanding knowledge of vRNA packaging signals to establish influenza virus vectors for the expression of foreign genes, we studied the replicative properties of this virus in cell culture and mice. Compared to wild-type virus, GFP(NA)-Flu was highly attenuated in normal cultured cells but was able to grow to a titer of >106 PFU/ml in a mutant cell line expressing reduced levels of sialic acid on the cell surface. GFP expression from this virus was stable even after five passages in the latter cells. In intranasally infected mice, GFP was detected in the epithelial cells of nasal mucosa, bronchioles, and alveoli for up to 4 days postinfection. We attribute the attenuated growth of GFP(NA)-Flu to virion aggregation at the surface of bronchiolar epithelia. In studies to test the potential of this mutant as a live attenuated influenza vaccine, all mice vaccinated with ≥105 PFU of GFP(NA)-Flu survived when challenged with lethal doses of the parent virus. These results suggest that influenza virus could be a useful vector for expressing foreign genes and that a sialidase-deficient virus may offer an alternative to the live influenza vaccines recently approved for human use.

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