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Rescooped by Mel Melendrez-Vallard from Virology and Bioinformatics from Virology.ca
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Influenza Viruses and mRNA Splicing: Doing More with Less

During their nuclear replication stage, influenza viruses hijack the host splicing machinery to process some of their RNA segments, the M and NS segments. In this review, we provide an overview of the current knowledge gathered on this interplay between influenza viruses and the cellular spliceosome, with a particular focus on influenza A viruses (IAV). These viruses have developed accurate regulation mechanisms to reassign the host spliceosome to alter host cellular expression and enable an optimal expression of specific spliced viral products throughout infection. Moreover, IAV segments undergoing splicing display high levels of similarity with human consensus splice sites and their viral transcripts show noteworthy secondary structures. Sequence alignments and consensus analyses, along with recently published studies, suggest both conservation and evolution of viral splice site sequences and structure for improved adaptation to the host. Altogether, these results emphasize the ability of IAV to be well adapted to the host’s splicing machinery, and further investigations may contribute to a better understanding of splicing regulation with regard to viral replication, host range, and pathogenesis


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burkesquires's curator insight, June 12, 7:44 AM

Nice review of RNA splicing in influenza virus.

Influenza
Flu in all Forms, Be Informed...Not Panicked.
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Viral evolution: Past, present and future of influenza viruses : Nature Reviews Microbiology : Nature Publishing Group

Viral evolution: Past, present and future of influenza viruses : Nature Reviews Microbiology : Nature Publishing Group | Influenza | Scoop.it
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Avian Flu Diary: UK: Defra Assessment Of Recent H5N8 Outbreaks In Germany & Italy

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Avian Flu Diary: Germany Adopts New Stringent Bird Flu Protection Regulations

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Highly Pathogenic H5 Avian Influenza Confirmed in Wild Birds in Washington State H5N2 Found in Northern Pintail Ducks & H5N8 Found in Captive Gyrfalcons | USDA Newsroom

WASHINGTON, Dec. 17, 2014 — The United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed the presence of highly pathogenic (HPAI) H5 avian influenza in wild birds in Whatcom County, Washington.
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Influenza: Get the (Antigenic) Drift - YouTube

Have you ever wondered why you need a flu vaccination each year? The National Institute of Allergy and Infectious Diseases explains the ever-changing nature ...
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Avian Flu Diary: OIE/APHIS: HPAI H5N8 & H5N2 Detected In Washington State Wild Birds

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Influenza A virus Acquires Enhanced Pathogenicity and Transmissibility After Serial Passages in Swine

Genetic and phylogenetic analyses suggest that the pandemic H1N1/2009 virus was derived from well-established swine influenza lineages; however, there is no convincing evidence that the pandemic virus was generated from a direct precursor in pigs. Furthermore, the evolutionary dynamics of influenza virus in pigs have not been well documented. Here, we subjected a recombinant virus (rH1N1) with the same constellation makeup as the pandemic H1N1/2009 virus to nine serial passages in pigs. Severity of infection sequentially increased with each passage. Deep sequencing of viral quasi-species from the ninth passage found five consensus amino acid mutations: PB1 A469T, PA 1129T, NA N329D, NS1 N205K and NEP T48N. Mutations in the HA protein, however, differed greatly between the upper and lower respiratory tracts. Three representative viral clones with the five consensus mutations were selected for functional evaluation. Relative to the parental virus, the three viral clones showed enhanced replication and polymerase activity in vitro, and enhanced replication, pathogenicity and transmissibility in pigs, guinea pigs and ferrets in vivo. Specifically, two mutants of rH1N1 (PB1 A469T, and combined NS1 N205K and NEP T48N) were identified as determinants of transmissibility in guinea pigs. Crucially, one mutant viral clone with the five consensus mutations, which also carried D187E, K211E and S289N mutations in its hemagglutinin (HA), was additionally able to infect ferrets by airborne transmission as effectively the pandemic virus. Our findings demonstrate that influenza virus can acquire viral characteristics that are similar to those of the pandemic virus after limited serial passages in pigs.


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Avian Flu Diary: EID Journal: A Proposed Strategy For Wild Bird Avian Influenza Surveillance

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Avian Flu Diary: ECDC Rapid Risk Assessment On Recent Spike In Egyptian H5N1 Cases

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Pandemic H1N1 virus transmission and shedding dynamics in index case households of a prospective Vietnamese cohort

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Canada: CFIA Statement On Genetic Sequencing Of H5N2

Credit CFIA   # 9459 The Canadian Food Inspection Agency (CFIA), has posted the follow statement characterizing the HPAI H5N2 virus that was first detected on a Fraser Valley poultry farm 18 days ago.   It is confirmed to be a reassortant...
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Rescooped by Mel Melendrez-Vallard from Pharma Biotech Industry Review (Krishan Maggon)
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Structural insight into cap-snatching and RNA synthesis by influenza polymerase

Influenza virus polymerase uses a capped primer, derived by ‘cap-snatching’ from host pre-messenger RNA, to transcribe its RNA genome into mRNA and a stuttering mechanism to generate the poly(A) tail. By contrast, genome replication is unprimed and generates exact full-length copies of the template. Here we use crystal structures of bat influenza A and human influenza B polymerases (FluA and FluB), bound to the viral RNA promoter, to give mechanistic insight into these distinct processes. In the FluA structure, a loop analogous to the priming loop of flavivirus polymerases suggests that influenza could initiate unprimed template replication by a similar mechanism. Comparing the FluA and FluB structures suggests that cap-snatching involvesin situ rotation of the PB2 cap-binding domain to direct the capped primer first towards the endonuclease and then into the polymerase active site. The polymerase probably undergoes considerable conformational changes to convert the observed pre-initiation state into the active initiation and elongation states.


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Krishan Maggon 's curator insight, December 18, 3:47 AM

Structural insight into cap-snatching and RNA synthesis by influenza polymeraseStefan Reich,Delphine Guilligay,Alexander Pflug,Hélène Malet,Imre Berger,Thibaut Crépin,Darren Hart,Thomas Lunardi,Max Nanao,Rob W. H. Ruigrok& Stephen CusackAffiliationsContributionsCorresponding authorNature 516, 361–366 (18 December 2014) doi:10.1038/nature14009Received 18 August 2014 Accepted 29 October 2014 Published online 19 November 2014

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IL-28B is a Key Regulator of B- and T-Cell Vaccine Responses against Influenza

From molecules to physiology
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Phylogeography of Avian influenza A H9N2 in China

Background:
During the past two decades, avian influenza A H9N2 viruses have spread geographically and ecologically in China.
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Rescooped by Mel Melendrez-Vallard from Virology and Bioinformatics from Virology.ca
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Pyrosequencing reveals an oseltamivir-resistant marker in the quasispecies of avian influenza A (H7N9) virus - Journal of Microbiology, Immunology and Infection

Prompt diagnosis of an oseltamivir-resistant marker is important for patient management, in particular to prevent the spread of resistant strains in the recent human H7N9 outbreak. We tailored a pyrosequencing assay to reveal neuraminidase R292K, a resistant marker found in one isolate from China, and demonstrated its performance in both sensitivity and specificity. In addition, a semi-nested polymerase chain reaction was applied, which enhanced the detection rate by at least 10-fold. We validated this assay by examining the marker in Taiwan's first imported human case and found R and K in quasispecies.


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Rescooped by Mel Melendrez-Vallard from Virology and Bioinformatics from Virology.ca
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Influenza Virus-Host Interactome Screen as a Platform for Antiviral Drug Development


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