scholarly journals Molecular Characterization of Influenza Virus in Intestines and its Effect on Intestinal Microbiota

2020 ◽  
Author(s):  
Heba Al Khatib ◽  
Muna Al Maslamani ◽  
Peter Coyle ◽  
Sameer Pathan ◽  
Asmaa Al Thani ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Molecular Characterization ◽  
Intestinal Microbiota ◽  
Influenza Infection ◽  
Influenza Viruses ◽  
Viral Rna ◽  
Intestinal Infection ◽  
Virus Growth ◽  
Fecal Samples

Background: Influenza predominantly causes respiratory diseases; however, gastrointestinal symptoms are not uncommonly reported, particularly among high-risk groups. Influenza virus RNA has been also detected in stools of patients infected with pandemic and seasonal influenza, however, the role and the clinical significance of intestinal infection has not been clearly demonstrated. Methods: Here, we used NGS technology to investigate molecular characterization of viral RNA shedding in feces of adults with active influenza infection. Paired nasal and fecal samples were collected from 295 patients showing to emergency department at Hamad Medical Corporation with flu-like symptoms during January 2018 and April 2019. Results: Among these, 90 nasal samples were positive for influenza, of which, 26 fecal samples were positive for influenza in real-time PCR and only five showed virus growth in both monolayer and 3D cell culture. Full genome sequencing of isolated viruses revealed some unique mutations that we are currently in the process of studying their effect on virus kinetics. Then, we investigated the potential impact of respiratory influenza infection on intestinal microbiota diversity and composition. Microbiome analysis results suggest that changes in gut microbiota composition in influenza-infected patients are significantly associated with (1) influenza virus type, and (2) the presence of viral RNA in intestines of infected patients. We also identified bacterial taxa for which relative abundance was significantly higher in the patients with severe respiratory symptoms. Conclusion: Altogether, our findings suggest that influenza viruses can affect intestinal environment either by direct intestinal infection or indirectly by modulating intestinal microbiota.

scholarly journals Functional Analysis of PA Binding by Influenza A Virus PB1: Effects on Polymerase Activity and Viral Infectivity

2001 ◽  
Vol 75 (17) ◽  
pp. 8127-8136 ◽  
Author(s):  
Daniel R. Perez ◽  
Ruben O. Donis
Keyword(s):  
Amino Acids ◽  
Influenza Virus ◽  
Amino Acid ◽  
Viral Replication ◽  
Influenza A Virus ◽  
Influenza A ◽  
Amino Acid Sequences ◽  
Influenza Viruses ◽  
Virus Growth ◽  
Transcription And Replication

ABSTRACT Influenza A virus expresses three viral polymerase (P) subunits—PB1, PB2, and PA—all of which are essential for RNA and viral replication. The functions of P proteins in transcription and replication have been partially elucidated, yet some of these functions seem to be dependent on the formation of a heterotrimer for optimal viral RNA transcription and replication. Although it is conceivable that heterotrimer subunit interactions may allow a more efficient catalysis, direct evidence of their essentiality for viral replication is lacking. Biochemical studies addressing the molecular anatomy of the P complexes have revealed direct interactions between PB1 and PB2 as well as between PB1 and PA. Previous studies have shown that the N-terminal 48 amino acids of PB1, termed domain α, contain the residues required for binding PA. We report here the refined mapping of the amino acid sequences within this small region of PB1 that are indispensable for binding PA by deletion mutagenesis of PB1 in a two-hybrid assay. Subsequently, we used site-directed mutagenesis to identify the critical amino acid residues of PB1 for interaction with PA in vivo. The first 12 amino acids of PB1 were found to constitute the core of the interaction interface, thus narrowing the previous boundaries of domain α. The role of the minimal PB1 domain α in influenza virus gene expression and genome replication was subsequently analyzed by evaluating the activity of a set of PB1 mutants in a model reporter minigenome system. A strong correlation was observed between a functional PA binding site on PB1 and P activity. Influenza viruses bearing mutant PB1 genes were recovered using a plasmid-based influenza virus reverse genetics system. Interestingly, mutations that rendered PB1 unable to bind PA were either nonviable or severely growth impaired. These data are consistent with an essential role for the N terminus of PB1 in binding PA, P activity, and virus growth.

scholarly journals Phylogenetic and molecular characterization of equine H3N8 influenza viruses from Greece (2003 and 2007): Evidence for reassortment between evolutionary lineages

2011 ◽  
Vol 8 (1) ◽  
pp. 350 ◽  
Author(s):  
Maria Bountouri ◽  
Eirini Fragkiadaki ◽  
Vasileios Ntafis ◽  
Theo Kanellos ◽  
Eftychia Xylouri
Keyword(s):  
Molecular Characterization ◽  
Influenza Viruses ◽  
Evolutionary Lineages

scholarly journals RNA-Sequencing-Based Transcriptomic Analysis Reveals a Role for Annexin-A1 in Classical and Influenza A Virus-Induced Autophagy

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1399 ◽  
Author(s):  
Jianzhou Cui ◽  
Dhakshayini Morgan ◽  
Dao Han Cheng ◽  
Sok Lin Foo ◽  
Gracemary L. R. Yap ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Influenza A ◽  
Influenza Infection ◽  
Critical Role ◽  
Mtor Inhibitors ◽  
Influenza Viruses ◽  
Annexin A1 ◽  
Underlying Mechanisms

Influenza viruses have been shown to use autophagy for their survival. However, the proteins and mechanisms involved in the autophagic process triggered by the influenza virus are unclear. Annexin-A1 (ANXA1) is an immunomodulatory protein involved in the regulation of the immune response and Influenza A virus (IAV) replication. In this study, using clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 (CRISPR associated protein 9) deletion of ANXA1, combined with the next-generation sequencing, we systematically analyzed the critical role of ANXA1 in IAV infection as well as the detailed processes governing IAV infection, such as macroautophagy. A number of differentially expressed genes were uniquely expressed in influenza A virus-infected A549 parental cells and A549 ∆ANXA1 cells, which were enriched in the immune system and infection-related pathways. Gene ontology and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway revealed the role of ANXA1 in autophagy. To validate this, the effect of mechanistic target of rapamycin (mTOR) inhibitors, starvation and influenza infection on autophagy was determined, and our results demonstrate that ANXA1 enhances autophagy induced by conventional autophagy inducers and influenza virus. These results will help us to understand the underlying mechanisms of IAV infection and provide a potential therapeutic target for restricting influenza viral replication and infection.

Molecular characterization of a novel reassortant H1N2 influenza virus containing genes from the 2009 pandemic human H1N1 virus in swine from eastern China

Virus Genes ◽  
2016 ◽  
Vol 52 (3) ◽  
pp. 405-410 ◽  
Author(s):  
Xiuming Peng ◽  
Haibo Wu ◽  
Lihua Xu ◽  
Xiaorong Peng ◽  
Linfang Cheng ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Molecular Characterization ◽  
H1n1 Virus ◽  
Eastern China

scholarly journals Cleavage of Influenza A Virus Hemagglutinin in Human Respiratory Epithelium Is Cell Associated and Sensitive to Exogenous Antiproteases

2002 ◽  
Vol 76 (17) ◽  
pp. 8682-8689 ◽  
Author(s):  
Oleg P. Zhirnov ◽  
Mine R. Ikizler ◽  
Peter F. Wright
Keyword(s):  
Molecular Weight ◽  
Influenza Virus ◽  
Serine Proteases ◽  
Influenza A ◽  
Extracellular Fluid ◽  
Respiratory Epithelium ◽  
Influenza Viruses ◽  
Secretory Cells ◽  
Low Molecular Weight ◽  
Virus Growth

ABSTRACT Proteolytic cleavage of the hemagglutinin (HA) of human influenza viruses A/Aichi/2/68 (H3N2) and A/WSN/34 (H1N1) from HA0 to HA1/HA2 was studied in primary human adenoid epithelial cells (HAEC). HAEC contain a mixture of ciliated and nonciliated secretory cells and mimic the epithelium membrane of the human respiratory tract. Pulse-chase labeling with [35S]methionine and Western blot analysis with anti-HA antibodies of cellular and virion polypeptides showed that HAEC cleaved newly synthesized HA0 to HA1/HA2 (“cleavage from within”) and significant amounts of cleaved HA accumulated within cells. It was also shown that HAEC was able to cleave HA0 of incoming virions (“cleavage from without”), whereas the HA0 of nonabsorbed virions free in extracellular fluid were not cleaved, supporting the conclusion that HA0 cleavage in HAEC is cell associated. Low-molecular-weight inhibitors of serine proteases, aprotinin and leupeptin, when added to influenza virus-infected HAEC suppressed HA0 cleavage and reduced the amount of cleaved HA1/HA2 both in cells and in progeny virions and thus diminished the infectivity of the virus. In contrast, the addition of fetal bovine serum, containing a number of high-molecular-weight antiproteases that compete for proteases in the extracellular environment, did not inhibit influenza virus growth in HAEC. These data suggest that in human respiratory epithelium the cleavage of influenza virus HA containing a single arginine in the proteolytic site (i) is a cell-associated process accomplished by serine-type protease(s) and (ii) is sensitive to low-molecular-weight exogenous inhibitors of serine proteases.

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