scholarly journals vRNA-vRNA interactions in influenza A virus HA vRNA packaging

2020 ◽  
Author(s):  
Sho Miyamoto ◽  
Yukiko Muramoto ◽  
Keiko Shindo ◽  
Yoko Fujita ◽  
Takeshi Morikawa ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Influenza Viruses ◽  
Packaging Signal ◽  
Genome Packaging ◽  
Coding Regions ◽  
Signal Region ◽  
Rna Interaction ◽  
Negative Sense

AbstractThe genome of the influenza A virus is composed of eight single-stranded negative-sense RNA segments (vRNAs). The eight different vRNAs are selectively packaged into progeny virions. This process likely involves specific interactions among vRNAs via segment-specific packaging signals located in the 3’ and 5’ terminal coding regions of vRNAs. To identify vRNA(s) that interact with hemagglutinin (HA) vRNA during genome packaging, we generated a mutant virus, HA 5m2, which possessed five silent mutations in the 5’ packaging signal region of HA vRNA. The HA 5m2 virus had a specific defect in HA vRNA incorporation, which reduced the viral replication efficiency. After serial passaging in cells, the virus acquired additional mutations in the 5’ terminal packaging signal regions of both HA and PB2 vRNAs. These mutations contributed to recovery of viral growth and packaging efficiency of HA vRNA. A direct RNA-RNA interaction between the 5’ ends of HA and PB2 vRNAs was confirmed in vitro. Our results indicate that direct interactions of HA vRNA with PB2 vRNA via their packaging signal regions are important for selective genome packaging and enhance our knowledge on the emergence of pandemic influenza viruses through genetic reassortment.

scholarly journals Packaging signal of influenza A virus

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Xiuli Li ◽  
Min Gu ◽  
Qinmei Zheng ◽  
Ruyi Gao ◽  
Xiufan Liu
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Packaging Signal ◽  
Genome Packaging ◽  
Genetic Reassortment ◽  
A Genome ◽  
Virus Genotypes ◽  
Virus Packaging ◽  
Negative Sense ◽  
Packaging Signals

AbstractInfluenza A virus (IAV) contains a genome with eight single-stranded, negative-sense RNA segments that encode 17 proteins. During its assembly, all eight separate viral RNA (vRNA) segments are incorporated into virions in a selective manner. Evidence suggested that the highly selective genome packaging mechanism relies on RNA-RNA or protein-RNA interactions. The specific structures of each vRNA that contribute to mediating the packaging of the vRNA into virions have been described and identified as packaging signals. Abundant research indicated that sequences required for genome incorporation are not series and are varied among virus genotypes. The packaging signals play important roles in determining the virus replication, genome incorporation and genetic reassortment of influenza A virus. In this review, we discuss recent studies on influenza A virus packaging signals to provide an overview of their characteristics and functions.

scholarly journals Importance of both the Coding and the Segment-Specific Noncoding Regions of the Influenza A Virus NS Segment for Its Efficient Incorporation into Virions

2005 ◽  
Vol 79 (6) ◽  
pp. 3766-3774 ◽  
Author(s):  
Ken Fujii ◽  
Yutaka Fujii ◽  
Takeshi Noda ◽  
Yukiko Muramoto ◽  
Tokiko Watanabe ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Virus Genome ◽  
Noncoding Region ◽  
Coding Region ◽  
Genome Packaging ◽  
Noncoding Regions ◽  
Coding Regions ◽  
Negative Sense ◽  
Incorporation Efficiency

ABSTRACT The genome of influenza A virus consists of eight single-strand negative-sense RNA segments, each comprised of a coding region and a noncoding region. The noncoding region of the NS segment is thought to provide the signal for packaging; however, we recently showed that the coding regions located at both ends of the hemagglutinin and neuraminidase segments were important for their incorporation into virions. In an effort to improve our understanding of the mechanism of influenza virus genome packaging, we sought to identify the regions of NS viral RNA (vRNA) that are required for its efficient incorporation into virions. Deletion analysis showed that the first 30 nucleotides of the 3′ coding region are critical for efficient NS vRNA incorporation and that deletion of the 3′ segment-specific noncoding region drastically reduces NS vRNA incorporation into virions. Furthermore, silent mutations in the first 30 nucleotides of the 3′ NS coding region reduced the incorporation efficiency of the NS segment and affected virus replication. These results suggested that segment-specific noncoding regions together with adjacent coding regions (especially at the 3′ end) form a structure that is required for efficient influenza A virus vRNA packaging.

scholarly journals Antiviral Activity of Benzoic Acid Derivative NC-5 Against Influenza A Virus and Its Neuraminidase Inhibition

2019 ◽  
Vol 20 (24) ◽  
pp. 6261
Author(s):  
Min Guo ◽  
Jiawei Ni ◽  
Jie Yu ◽  
Jing Jin ◽  
Lingman Ma ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Benzoic Acid ◽  
Influenza A Virus ◽  
Influenza A ◽  
Matrix Protein ◽  
Influenza Viruses ◽  
Drug Candidate ◽  
Dependent Manner ◽  
Drug Resistant

The currently available drugs against influenza A virus primarily target neuraminidase (NA) or the matrix protein 2 (M2) ion channel. The emergence of drug-resistant viruses requires the development of new antiviral chemicals. Our study applied a cell-based approach to evaluate the antiviral activity of a series of newly synthesized benzoic acid derivatives, and 4-(2,2-Bis(hydroxymethyl)-5-oxopyrrolidin-l-yl)-3-(5-cyclohexyl-4H-1,2,4-triazol-3-yl)amino). benzoic acid, termed NC-5, was found to possess antiviral activity. NC-5 inhibited influenza A viruses A/FM/1/47 (H1N1), A/Beijing/32/92 (H3N2) and oseltamivir-resistant mutant A/FM/1/47-H275Y (H1N1-H275Y) in a dose-dependent manner. The 50% effective concentrations (EC50) for H1N1 and H1N1-H275Y were 33.6 μM and 32.8 μM, respectively, which showed that NC-5 had a great advantage over oseltamivir in drug-resistant virus infections. The 50% cytotoxic concentration (CC50) of NC-5 was greater than 640 μM. Orally administered NC-5 protected mice infected with H1N1 and H1N1-H275Y, conferring 80% and 60% survival at 100 mg/kg/d, reducing body weight loss, and alleviating virus-induced lung injury. NC-5 could suppress NP and M1 protein expression levels during the late stages of viral biosynthesis and inhibit NA activity, which may influence virus release. Our study proved that NC-5 has potent anti-influenza activity in vivo and in vitro, meaning that it could be regarded as a promising drug candidate to treat infection with influenza viruses, including oseltamivir-resistant viruses.

scholarly journals Influenza A Virus Inhibits RSV Infection via a Two-Wave Expression of IFIT Proteins

Viruses ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1171
Author(s):  
Yaron Drori ◽  
Jasmine Jacob-Hirsch ◽  
Rakefet Pando ◽  
Aharona Glatman-Freedman ◽  
Nehemya Friedman ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Influenza Viruses ◽  
Mass Spectrometry Analysis ◽  
Influenza A Viruses ◽  
Rsv Infection ◽  
Syncytial Virus ◽  
Mouse Lungs

Influenza viruses and respiratory syncytial virus (RSV) are respiratory viruses that primarily circulate worldwide during the autumn and winter seasons. Seasonal surveillance has shown that RSV infection generally precedes influenza. However, in the last four winter seasons (2016–2020) an overlap of the morbidity peaks of both viruses was observed in Israel, and was paralleled by significantly lower RSV infection rates. To investigate whether the influenza A virus inhibits RSV, human cervical carcinoma (HEp2) cells or mice were co-infected with influenza A and RSV. Influenza A inhibited RSV growth, both in vitro and in vivo. Mass spectrometry analysis of mouse lungs infected with influenza A identified a two-wave pattern of protein expression upregulation, which included members of the interferon-induced protein with the tetratricopeptide (IFITs) family. Interestingly, in the second wave, influenza A viruses were no longer detectable in mouse lungs. In addition, knockdown and overexpression of IFITs in HEp2 cells affected RSV multiplicity. In conclusion, influenza A infection inhibits RSV infectivity via upregulation of IFIT proteins in a two-wave modality. Understanding the immune system involvement in the interaction between influenza A and RSV viruses will contribute to the development of future treatment strategies against these viruses.

scholarly journals Antiviral Activity of Aspalathus linearis against Human Influenza Virus

2017 ◽  
Vol 12 (4) ◽  
pp. 1934578X1701200 ◽  
Author(s):  
Ratika Rahmasari ◽  
Takahiro Haruyama ◽  
Siriwan Charyasriwong ◽  
Tomoki Nishida ◽  
Nobuyuki Kobayashi
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Influenza A ◽  
Time Course ◽  
Influenza Viruses ◽  
Replication Process ◽  
Human Influenza Virus ◽  
Alkaline Extract ◽  
Aspalathus Linearis

Influenza A viruses are responsible for annual epidemics and occasional pandemics, which cause significant morbidity and mortality. The limited protection offered by influenza vaccination, and the emergence of drug-resistant influenza strains, highlight the urgent need for the development of novel anti-influenza drugs. However, the search for antiviral substances from the library of low molecular weight chemical compounds is limited. Thus, because of their natural diversity and accessibility, plants or plant-derived materials are rapidly becoming valuable sources for the discovery and development of new antiviral drugs. In this study, crude extracts of Aspalathus linearis, a plant reported to have anti-HIV activity, were evaluated in vitro for their activity against the influenza A virus. Of the extracts tested, an alkaline extract of Aspalathus linearis demonstrated the strongest inhibition against influenza A virus and could also inhibit different types of influenza viruses, including Oseltamivir-resistant influenza viruses A and B. Our time course of addition studies indicated that the alkaline extract of Aspalathus linearis exerts its antiviral effect predominantly during the late stages of the influenza virus replication process.

scholarly journals Cross-Protection of Influenza A Virus Infection by a DNA Aptamer Targeting the PA Endonuclease Domain

2015 ◽  
Vol 59 (7) ◽  
pp. 4082-4093 ◽  
Author(s):  
Shuofeng Yuan ◽  
Naru Zhang ◽  
Kailash Singh ◽  
Huiping Shuai ◽  
Hin Chu ◽  
...  
Keyword(s):  
Virus Infection ◽  
Influenza A Virus ◽  
Influenza A ◽  
H5n1 Virus ◽  
Influenza Viruses ◽  
Cross Protection ◽  
Dna Aptamer ◽  
Endonuclease Activity ◽  
Endonuclease Domain

ABSTRACTAmino acid residues in the N-terminal of the PA subunit (PAN) of the influenza A virus polymerase play critical roles in endonuclease activity, protein stability, and viral RNA (vRNA) promoter binding. In addition, PANis highly conserved among different subtypes of influenza virus, which suggests PANto be a desired target in the development of anti-influenza agents. We selected DNA aptamers targeting the intact PA protein or the PANdomain of an H5N1 virus strain using systematic evolution of ligands by exponential enrichment (SELEX). The binding affinities of selected aptamers were measured, followed by an evaluation ofin vitroendonuclease inhibitory activity. Next, the antiviral effects of enriched aptamers against influenza A virus infections were examined. A total of three aptamers targeting PA and six aptamers targeting PANwere selected. Our data demonstrated that all three PA-selected aptamers neither inhibited endonuclease activity nor exhibited antiviral efficacy, whereas four of the six PAN-selected aptamers inhibited both endonuclease activity and H5N1 virus infection. Among the four effective aptamers, one exhibited cross-protection against infections of H1N1, H5N1, H7N7, and H7N9 influenza viruses, with a 50% inhibitory concentration (IC50) of around 10 nM. Notably, this aptamer was identified at the 5th round but disappeared after the 10th round of selection, suggesting that the identification and evaluation of aptamers at early rounds of selection may be highly helpful for screening effective aptamers. Overall, our study provides novel insights for screening and developing effective aptamers for use as anti-influenza drugs.

scholarly journals Identification and targeting of a pan-genotypic influenza A virus RNA structure that mediates packaging and disease.

2021 ◽  
Author(s):  
Rachel J. Hagey ◽  
Menashe Elazar ◽  
Siqi Tian ◽  
Edward A. Pham ◽  
Wipapat Kladwang ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Rna Structure ◽  
Influenza A ◽  
Locked Nucleic Acid ◽  
Antiviral Resistance ◽  
Packaging Signal ◽  
Oseltamivir Carboxylate ◽  
Virus Rna ◽  
Different Strains

Currently approved anti-influenza drugs target viral proteins, are subtype limited, and are challenged by rising antiviral resistance. To overcome these limitations, we sought to identify a conserved essential RNA secondary structure within the genomic RNA predicted to have greater constraints on mutation in response to therapeutics targeting this structure. Here, we identified and genetically validated an RNA stemloop structure we termed PSL2, which serves as a packaging signal for genome segment PB2 and is highly conserved across influenza A virus (IAV) isolates. RNA structural modeling rationalized known packaging-defective mutations and allowed for predictive mutagenesis tests. Disrupting and compensating mutations of PSL2's structure give striking attenuation and restoration, respectively, of in vitro virus packaging and mortality in mice. Antisense Locked Nucleic Acid oligonucleotides (LNAs) designed against PSL2 dramatically inhibit IAV in vitro against viruses of different strains and subtypes, possess a high barrier to the development of antiviral resistance, and are equally effective against oseltamivir carboxylate-resistant virus. A single dose of LNA administered 3 days after, or 14 days before, a lethal IAV inoculum provides 100% survival. Moreover, such treatment led to the development of strong immunity to rechallenge with a ten-fold lethal inoculum. Together, these results have exciting implications for the development of a versatile novel class of antiviral therapeutics capable of prophylaxis, post-exposure treatment, and 'just-in-time' universal vaccination against all IAV strains, including drug-resistant pandemics.

scholarly journals Beneficial Effect of Indigo Naturalis on Acute Lung Injury Induced by Influenza a Virus

2020 ◽  
Author(s):  
Peng Tu ◽  
Rong Tian ◽  
Yan Lu ◽  
Yunyi Zhang ◽  
Haiyan Zhu ◽  
...  
Keyword(s):  
Acute Lung Injury ◽  
Lung Injury ◽  
Influenza A Virus ◽  
Lung Tissue ◽  
Influenza A ◽  
Influenza Viruses ◽  
Virus Growth ◽  
Indigo Naturalis ◽  
Anti Inflammatory

Abstract Background: Infections induced by influenza viruses, as well as COVID-19 pandemic induced by SARS-CoV-2 led to Acute lung injury (ALI) and multiorgan failure, during which traditional Chinese medicine played an important role in treatment of the pandemic. The study aimed to investigate the effect of indigo naturalis on ALI induced by influenza A virus (IAV) in mice.Method: The anti-influenza and anti-inflammatory properties of aqueous extracts of indigo naturalis (INAE) were evaluated in vitro. BALB/c mice inoculated intranasally with IAV (H1N1) were treated intragastrically with INAE (40, 80 and 160 mg kg-1/d) 2 h later for 4 or 7 days. Animal mortality and lifespan were recorded. Expression of high mobility group box-1 protein (HMGB-1) and toll-like receptor-4 (TLR4) were evaluated through immunohistological staining. Inflammatory cytokines were also monitored by ELISA.Result: INAE inhibited virus growth on Madin-Darby canine kidney (MDCK) cells and decreased nitric oxide (NO) production from lipopolysaccharide (LPS)-stimulated peritoneal macrophage in vitro. The results showed that oral administration of 160 mg/kg of INAE significantly improved the lifespan (P < 0.01) and survival rate of IAV infected mice, improved lung injury and lowered viral replication in lung tissue (P < 0.01). Treatment with INAE (40, 80 and 160 mg/kg) also significantly increased liver weight and liver index (P < 0.05), as well as spleen and thymus weight and organ index at 160 mg/kg (P < 0.05). The expression of HMGB-1 and TLR4 in lung tissue were also suppressed. Treatment with INAE reduced the high levels of interferon α (IFN-α), interferon β (IFN-β), interferon γ (IFN-γ), monocyte chemoattractant protein-1 (MCP-1), regulated upon activation normal T cell expressed and secreted factor (RANTES), interferon induced protein-10 (IP-10), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) (P < 0.05), with increased production of interleukin-10 (IL-10) (P < 0.05). The increased myeloperoxidase (MPO) activity and methylene dioxyamphetamine (MDA) level in lung tissues were inhibited by INAE treatment (P < 0.05).Conclusion: The results showed that INae alleviated IAV induced ALI in mice. The effect of INAE might be related with its anti-virus, anti-inflammatory and anti-oxidation properties, which give a hint that indigo naturalis might be effective on respiratory viruses infected acute lung injury or SAR-CoV-2 caused COVID-19.

scholarly journals Virtual Screening Identifies Chebulagic Acid as an Inhibitor of the M2(S31N) Viral Ion Channel and Influenza A Virus

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2903
Author(s):  
Maggie C. Duncan ◽  
Pascal Amoa Onguéné ◽  
Ibuki Kihara ◽  
Derrick N. Nebangwa ◽  
Maya E. Naidu ◽  
...  
Keyword(s):  
Ion Channel ◽  
Influenza A Virus ◽  
Influenza A ◽  
Influenza Viruses ◽  
Drug Resistant ◽  
M2 Protein ◽  
Virtual Screen ◽  
Chebulagic Acid ◽  
Virus Strains

The increasing prevalence of drug-resistant influenza viruses emphasizes the need for new antiviral countermeasures. The M2 protein of influenza A is a proton-gated, proton-selective ion channel, which is essential for influenza replication and an established antiviral target. However, all currently circulating influenza A virus strains are now resistant to licensed M2-targeting adamantane drugs, primarily due to the widespread prevalence of an M2 variant encoding a serine to asparagine 31 mutation (S31N). To identify new chemical leads that may target M2(S31N), we performed a virtual screen of molecules from two natural product libraries and identified chebulagic acid as a candidate M2(S31N) inhibitor and influenza antiviral. Chebulagic acid selectively restores growth of M2(S31N)-expressing yeast. Molecular modeling also suggests that chebulagic acid hydrolysis fragments preferentially interact with the highly-conserved histidine residue within the pore of M2(S31N) but not adamantane-sensitive M2(S31). In contrast, chebulagic acid inhibits in vitro influenza A replication regardless of M2 sequence, suggesting that it also acts on other influenza targets. Taken together, results implicate chebulagic acid and/or its hydrolysis fragments as new chemical leads for M2(S31N) and influenza-directed antiviral development.

scholarly journals Rescue of Influenza A Virus from Recombinant DNA

1999 ◽  
Vol 73 (11) ◽  
pp. 9679-9682 ◽  
Author(s):  
Ervin Fodor ◽  
Louise Devenish ◽  
Othmar G. Engelhardt ◽  
Peter Palese ◽  
George G. Brownlee ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Reverse Genetics ◽  
Recombinant Dna ◽  
Vero Cells ◽  
Influenza Viruses ◽  
Polymerase I ◽  
Negative Sense ◽  
Expression Plasmids ◽  
Delta Virus

ABSTRACT We have rescued influenza A virus by transfection of 12 plasmids into Vero cells. The eight individual negative-sense genomic viral RNAs were transcribed from plasmids containing human RNA polymerase I promoter and hepatitis delta virus ribozyme sequences. The three influenza virus polymerase proteins and the nucleoprotein were expressed from protein expression plasmids. This plasmid-based reverse genetics technique facilitates the generation of recombinant influenza viruses containing specific mutations in their genes.

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