scholarly journals Adaptation of an H7N7 equine influenza A virus in mice

2007 ◽  
Vol 88 (2) ◽  
pp. 547-553 ◽  
Author(s):  
Kyoko Shinya ◽  
Shinji Watanabe ◽  
Toshihiro Ito ◽  
Noriyuki Kasai ◽  
Yoshihiro Kawaoka
Keyword(s):  
Protein Expression ◽  
Influenza A Virus ◽  
Virus Replication ◽  
Viral Protein ◽  
Influenza A ◽  
Animal Species ◽  
Influenza A Viruses ◽  
Equine Influenza ◽  
Viral Protein Expression ◽  
Wild Waterfowl

Wild waterfowl are a reservoir for influenza A viruses, which can be transmitted from these birds to other animal species. Occasionally, influenza A viruses are transmitted to other animal species from animals other than wild waterfowl, e.g. an equine influenza virus has been transmitted to dogs and caused outbreaks. To understand the molecular mechanism by which influenza A viruses adapt to a new animal species, the molecular changes involved in the adaptation of an H7N7 equine influenza A virus were studied in mice. Mutations in the mouse-adapted virus mapped to one amino acid change in the PA protein, one in PB2 and two in PB1. Of these mutations, the Glu-to-Lys substitution at position 627 of PB2 (PB2-E627K) increased virulence appreciably. To understand the mechanism of this increased virulence, a recombinant virus expressing a reporter green fluorescent protein was constructed, thus enabling the effect of this mutation on viral protein expression to be tested in the context of virus replication in situ. It was found that the PB2-E627K substitution in this equine virus contributed to increased viral protein expression and virus replication in mouse cells and enhanced brain invasiveness in mice. These results demonstrate that the importance of the PB2-E627K substitution for mouse adaptation, which was identified previously in human H5N1 isolates, extends to equine influenza A virus.

scholarly journals Recombinant Influenza A Viruses with Enhanced Levels of PB1 and PA Viral Protein Expression

2012 ◽  
Vol 86 (10) ◽  
pp. 5926-5930 ◽  
Author(s):  
A. Belicha-Villanueva ◽  
J. R. Rodriguez-Madoz ◽  
J. Maamary ◽  
A. Baum ◽  
D. Bernal-Rubio ◽  
...  
Keyword(s):  
Protein Expression ◽  
Viral Protein ◽  
Influenza A ◽  
Influenza A Viruses ◽  
Viral Protein Expression

scholarly journals Human Sorting Nexin 2 Protein Interacts With Influenza A Virus PA Protein and Has a Negative Regulatory Effect on the Virus Replication

2021 ◽  
Author(s):  
Tugba Kocmar ◽  
Elif Caglayan ◽  
Erkan Rayaman ◽  
Kyosuke Nagata ◽  
Kadir Turan
Keyword(s):  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Yeast Cells ◽  
Influenza A Viruses ◽  
Rdrp Activity ◽  
Sorting Nexin ◽  
Amino Terminal ◽  
Viral Rdrp ◽  
Negative Effect

Abstract Replication of the influenza A viruses occurs in the cells through the viral RdRP consisting of PB1, PB2, and PA. Several cellular proteins are involved in these processes. To identify potential host interacting proteins to the viral PA, we have carried out a yeast two-hybrid screen using a HEK293 cell cDNA library. We focused our study on human SNX2 protein, which interacts with the PA protein in yeast cells. By using the co-immunoprecipitation assays, we have demonstrated that the amino-terminal part of the PA was important for binding to the SNX2 protein. Subcellular localization of the PA and human SNX2 proteins in HeLa cells supported this interaction. Knockdown of SNX2 with siRNA transfection in the cells resulted in a significant increase in both viral transcripts and proteins, suggesting that SNX2 could be a negative factor. However, the increase of SNX2 proteins in transfected cells didn’t cause a significant change in the viral RdRP activity in mini-replicon assay. This may suggest that the negative effect of SNX2 on the influenza A virus replication could be saturated with its authentic intra-cellular amount. Therefore, the regulatory mechanism for the amount of SNX2 is important to be studied in terms of influenza A virus replication.

scholarly journals The host factor ANP32A is required for influenza A virus vRNA and cRNA synthesis

2021 ◽  
Author(s):  
Benjamin E. Nilsson-Payant ◽  
Benjamin R. tenOever ◽  
Aartjan J.W. te Velthuis
Keyword(s):  
Avian Influenza ◽  
Rna Polymerase ◽  
Viral Replication ◽  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Host Factor ◽  
Rna Polymerases ◽  
Viral Rna ◽  
Influenza A Viruses

Influenza A viruses are negative-sense RNA viruses that rely on their own viral replication machinery to replicate and transcribe their segmented single-stranded RNA genome. The viral ribonucleoprotein complexes in which viral RNA is replicated consist of a nucleoprotein scaffold around which the RNA genome is bound, and a heterotrimeric RNA-dependent RNA polymerase that catalyzes viral replication. The RNA polymerase copies the viral RNA (vRNA) via a replicative intermediate, called the complementary RNA (cRNA), and subsequently uses this cRNA to make more vRNA copies. To ensure that new cRNA and vRNA molecules are associated with ribonucleoproteins in which they can be amplified, the active RNA polymerase recruits a second polymerase to encapsidate the cRNA or vRNA. Host factor ANP32A has been shown to be essential for viral replication and to facilitate the formation of a dimer between viral RNA polymerases. Differences between mammalian and avian ANP32A proteins are sufficient to restrict viral replication. It has been proposed that ANP32A is only required for the synthesis of vRNA molecules from a cRNA, but not vice versa. However, this view does not match recent molecular evidence. Here we use minigenome assays, virus infections, and viral promoter mutations to demonstrate that ANP32A is essential for both vRNA and cRNA synthesis. Moreover, we show that ANP32 is not only needed for the actively replicating polymerase, but also for the polymerase that is encapsidating nascent viral RNA products. Overall, these results provide new insights into influenza A virus replication and host adaptation. IMPORTANCE Zoonotic avian influenza A viruses pose a constant threat to global health, and they have the potential to cause pandemics. Species variations in host factor ANP32A play a key role in supporting the activity of avian influenza A virus RNA polymerases in mammalian hosts. Here we show that ANP32A acts at two stages in the influenza A virus replication cycle, supporting recent structural experiments, in line with its essential role. Understanding how ANP32A supports viral RNA polymerase activity and how it supports avian polymerase function in mammalian hosts is important for understanding influenza A virus replication and the development of antiviral strategies against influenza A viruses.

scholarly journals The CPSF30 Binding Site on the NS1A Protein of Influenza A Virus Is a Potential Antiviral Target

2006 ◽  
Vol 80 (8) ◽  
pp. 3957-3965 ◽  
Author(s):  
Karen Y. Twu ◽  
Diana L. Noah ◽  
Ping Rao ◽  
Rei-Lin Kuo ◽  
Robert M. Krug
Keyword(s):  
Amino Acid ◽  
Binding Site ◽  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Influenza B Virus ◽  
Influenza B ◽  
Influenza A Viruses ◽  
B Virus ◽  
Ns1a Protein

ABSTRACT The emergence of influenza A viruses resistant to the two existing classes of antiviral drugs highlights the need for additional antiviral drugs, particularly considering the potential threat of a pandemic of H5N1 influenza A viruses. Here, we determine whether influenza A virus replication can be selectively inhibited by blocking the ability of its NS1A protein to inhibit the 3′-end processing of cellular pre-mRNAs, including beta interferon (IFN-β) pre-mRNA. Pre-mRNA processing is inhibited via the binding of the NS1A protein to the cellular CPSF30 protein, and mutational inactivation of this NS1A binding site causes severe attenuation of the virus. We demonstrate that binding of CPSF30 is mediated by two of its zinc fingers, F2F3, and that the CPSF30/F2F3 binding site on the NS1A protein extends from amino acid 144 to amino acid 186. We generated MDCK cells that constitutively express epitope-tagged F2F3 in the nucleus, although at only approximately one-eighth the level of the NS1A protein produced during virus infection. Influenza A virus replication was inhibited in this cell line, whereas no inhibition was observed with influenza B virus, whose NS1B protein lacks a binding site for CPSF30. Influenza A virus, but not influenza B virus, induced increased production of IFN-β mRNA in the F2F3-expressing cells. These results, which indicate that F2F3 inhibits influenza A virus replication by blocking the binding of endogenous CPSF30 to the NS1A protein, point to this NS1A binding site as a potential target for the development of antivirals directed against influenza A virus.

scholarly journals The Short Form of the Zinc Finger Antiviral Protein Inhibits Influenza A Virus Protein Expression and Is Antagonized by the Virus-Encoded NS1

2016 ◽  
Vol 91 (2) ◽  
Author(s):  
Qiannan Tang ◽  
Xinlu Wang ◽  
Guangxia Gao
Keyword(s):  
Antiviral Activity ◽  
Protein Expression ◽  
Influenza A Virus ◽  
Zinc Finger ◽  
Viral Protein ◽  
Influenza A ◽  
Short Form ◽  
Virus Protein ◽  
Mrna Levels ◽  
Antiviral Protein

ABSTRACT Zinc finger antiviral protein (ZAP) is a host factor that specifically inhibits the replication of certain viruses. There are two ZAP isoforms arising from alternative splicing, which differ only at the C termini. It was recently reported that the long isoform (ZAPL) promotes proteasomal degradation of influenza A virus (IAV) proteins PA and PB2 through the C-terminal poly(ADP-ribose) polymerase (PARP) domain, which is missing in the short form (ZAPS), and that this antiviral activity is antagonized by the viral protein PB1. Here, we report that ZAP inhibits IAV protein expression in a PARP domain-independent manner. Overexpression of ZAPS inhibited the expression of PA, PB2, and neuraminidase (NA), and downregulation of the endogenous ZAPS enhanced their expression. We show that ZAPS inhibited PB2 protein expression by reducing the encoding viral mRNA levels and repressing its translation. However, downregulation of ZAPS only modestly enhanced the early stage of viral replication. We provide evidence showing that the antiviral activity of ZAPS is antagonized by the viral protein NS1. A recombinant IAV carrying an NS1 mutant that lost the ZAPS-antagonizing activity replicated better in ZAPS-deficient cells. We further provide evidence suggesting that NS1 antagonizes ZAPS by inhibiting its binding to target mRNA. These results uncover a distinct mechanism underlying the interactions between ZAP and IAV. IMPORTANCE ZAP is a host antiviral factor that has been extensively reported to inhibit the replication of certain viruses by repressing the translation and promoting the degradation of the viral mRNAs. There are two ZAP isoforms, ZAPL and ZAPS. ZAPL was recently reported to promote IAV protein degradation through the PARP domain. Whether ZAPS, which lacks the PARP domain, inhibits IAV and the underlying mechanisms remained to be determined. Here, we show that ZAPS posttranscriptionally inhibits IAV protein expression. This antiviral activity of ZAP is antagonized by the viral protein NS1. The fact that ZAP uses two distinct mechanisms to inhibit IAV infection and that the virus evolved different antagonists suggests an important role of ZAP in the host effort to control IAV infection and the importance of the threat of ZAP to the virus. The results reported here help us to comprehensively understand the interactions between ZAP and IAV.

scholarly journals Effects of Influenza A Virus NS1 Protein on Protein Expression: the NS1 Protein Enhances Translation and Is Not Required for Shutoff of Host Protein Synthesis

2002 ◽  
Vol 76 (3) ◽  
pp. 1206-1212 ◽  
Author(s):  
Mirella Salvatore ◽  
Christopher F. Basler ◽  
Jean-Patrick Parisien ◽  
Curt M. Horvath ◽  
Svetlana Bourmakina ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Expression ◽  
Influenza A Virus ◽  
Viral Protein ◽  
Influenza A ◽  
Vero Cells ◽  
Cellular Protein ◽  
Host Protein ◽  
Ns1 Protein ◽  
Host Protein Synthesis

ABSTRACT The influenza A virus NS1 protein, a virus-encoded alpha/beta interferon (IFN-α/β) antagonist, appears to be a key regulator of protein expression in infected cells. We now show that NS1 protein expression results in enhancement of reporter gene activity from transfected plasmids. This effect appears to be mediated at the translational level, and it is reminiscent of the activity of the adenoviral virus-associated I (VAI) RNA, a known inhibitor of the antiviral, IFN-induced, PKR protein. To study the effects of the NS1 protein on viral and cellular protein synthesis during influenza A virus infection, we used recombinant influenza viruses lacking the NS1 gene (delNS1) or expressing truncated NS1 proteins. Our results demonstrate that the NS1 protein is required for efficient viral protein synthesis in COS-7 cells. This activity maps to the amino-terminal domain of the NS1 protein, since cells infected with wild-type virus or with a mutant virus expressing a truncated NS1 protein—lacking approximately half of its carboxy-terminal end—showed similar kinetics of viral and cellular protein expression. Interestingly, no major differences in host cell protein synthesis shutoff or in viral protein expression were found among NS1 mutant viruses in Vero cells. Thus, another viral component(s) different from the NS1 protein is responsible for the inhibition of host protein synthesis during viral infection. In contrast to the earlier proposal suggesting that the NS1 protein regulates the levels of spliced M2 mRNA, no effects on M2 protein accumulation were seen in Vero cells infected with delNS1 virus.

scholarly journals PRESENCE OF RESPIRATORY VIRUSES IN EQUINES IN BRAZIL

2014 ◽  
Vol 56 (3) ◽  
pp. 191-195
Author(s):  
Dalva Assunção Portari Mancini ◽  
Aparecida Santo Pietro Pereira ◽  
Rita Maria Zucatelli Mendonça ◽  
Adelia Hiroko Nagamori Kawamoto ◽  
Rosely Cabette Barbosa Alves ◽  
...  
Keyword(s):  
Influenza A ◽  
Respiratory Viruses ◽  
Influenza Viruses ◽  
Influenza A Viruses ◽  
Equine Influenza ◽  
Hemagglutination Inhibition Test ◽  
Parainfluenza Viruses ◽  
Significant Difference ◽  
Antibody Titers ◽  
The Difference

Equines are susceptible to respiratory viruses such as influenza and parainfluenza. Respiratory diseases have adversely impacted economies all over the world. This study was intended to determine the presence of influenza and parainfluenza viruses in unvaccinated horses from some regions of the state of São Paulo, Brazil. Blood serum collected from 72 equines of different towns in this state was tested by hemagglutination inhibition test to detect antibodies for both viruses using the corresponding antigens. About 98.6% (71) and 97.2% (70) of the equines responded with antibody protective titers (≥ 80 HIU/25µL) H7N7 and H3N8 subtypes of influenza A viruses, respectively. All horses (72) also responded with protective titers (≥ 80) HIU/25µL against the parainfluenza virus. The difference between mean antibody titers to H7N7 and H3N8 subtypes of influenza A viruses was not statistically significant (p > 0.05). The mean titers for influenza and parainfluenza viruses, on the other hand, showed a statistically significant difference (p < 0.001). These results indicate a better antibody response from equines to parainfluenza 3 virus than to the equine influenza viruses. No statistically significant differences in the responses against H7N7 and H3N8 subtypes of influenza A and parainfluenza 3 viruses were observed according to the gender (female, male) or the age (≤ 2 to 20 years-old) groups. This study provides evidence of the concomitant presence of two subtypes of the equine influenza A (H7N7 and H3N8) viruses and the parainfluenza 3 virus in equines in Brazil. Thus, it is advisable to vaccinate equines against these respiratory viruses.

scholarly journals Investigating Influenza A Virus Infection: Tools To Track Infection and Limit Tropism: TABLE 1

2015 ◽  
Vol 89 (12) ◽  
pp. 6167-6170 ◽  
Author(s):  
Jessica K. Fiege ◽  
Ryan A. Langlois
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Therapeutic Interventions ◽  
Microrna Target ◽  
Influenza A Viruses ◽  
Host Interactions ◽  
Target Sites ◽  
Recent Developments ◽  
Cellular Tropism ◽  
The Relationship

Influenza A viruses display a broad cellular tropism within the respiratory tracts of mammalian hosts. Uncovering the relationship between tropism and virus immunity, pathogenesis, and transmission will be critical for the development of therapeutic interventions. Here we discuss recent developments of several recombinant strains of influenza A virus. These viruses have inserted reporters to track tropism, microRNA target sites to restrict tropism, or barcodes to assess transmission dynamics, expanding our understanding of pathogen-host interactions.

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