Project description:Influenza virus neuraminidase (NA), a type II transmembrane glycoprotein, is transported to the virus assembly site at the plasma membrane and is a major viral envelope component that plays a critical role in the release of progeny virions and in determination of host range restriction. Although signals/sequences in NA for translocation, sorting and raft association have been identified, little is known about the host factors that are involved in regulating the intracellular and cell surface transport of NA. In this report, we have investigated the involvement of Rho family GTPases in NA transport to the cell surface. We found that expression of constitutively active or inactive mutants of RhoA or Rac1 did not significantly affect the amount of NA that reached the cell surface. Interestingly, expression of constitutively active Cdc42 or depletion of the Cdc42-specific GAP, ARHGAP21, promoted the transport of NA to the plasma membranes. By contrast, cells expressing shRNA targrting Cdc42 or overexpressing ARHGAP21 exhibited a significant decrease in the amount of cell surface-localized NA. Furthermore, silencing of Cdc42 or ARHGAP21 had significant effects on influenza A virus replication. Together, our results reveal that ARHGAP21 and Cdc42-based signaling regulates the NA transport and thereby impacts virus replication. This microarray experiment was carried out to find out whether Cdc42 and ARHGAP21 expression levels in A549 cell were changed after WSN infection. Total RNAs were extracted from three different groups of A549 cells that had been infected with or without WSN for 10 h, using TRIzol reagent (Invitrogen, Carlsbad, CA). Samples were amplified and labeled using a NimbleGen One-Color DNA Labeling Kit.
Project description:Influenza virus neuraminidase (NA), a type II transmembrane glycoprotein, is transported to the virus assembly site at the plasma membrane and is a major viral envelope component that plays a critical role in the release of progeny virions and in determination of host range restriction. Although signals/sequences in NA for translocation, sorting and raft association have been identified, little is known about the host factors that are involved in regulating the intracellular and cell surface transport of NA. In this report, we have investigated the involvement of Rho family GTPases in NA transport to the cell surface. We found that expression of constitutively active or inactive mutants of RhoA or Rac1 did not significantly affect the amount of NA that reached the cell surface. Interestingly, expression of constitutively active Cdc42 or depletion of the Cdc42-specific GAP, ARHGAP21, promoted the transport of NA to the plasma membranes. By contrast, cells expressing shRNA targrting Cdc42 or overexpressing ARHGAP21 exhibited a significant decrease in the amount of cell surface-localized NA. Furthermore, silencing of Cdc42 or ARHGAP21 had significant effects on influenza A virus replication. Together, our results reveal that ARHGAP21 and Cdc42-based signaling regulates the NA transport and thereby impacts virus replication. This microarray experiment was carried out to find out whether Cdc42 and ARHGAP21 expression levels in A549 cell were changed after WSN infection.
Project description:While a common symptom of influenza and coronavirus disease 2019 (COVID-19) is fever, its physiological role on host resistance to viral infection remains less clear. Here, we demonstrate that exposure of mice to the high ambient temperature of 36 °C increase host resistance to viral pathogens including influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). High heat-exposed mice increase basal body temperature over 38 °C to enable more bile acids production in a gut microbiota-dependent manner. The gut microbiota-derived deoxycholic acid (DCA) and its plasma membrane-bound receptor Takeda G-protein-coupled receptor 5 (TGR5) signaling increase host resistance to influenza virus infection by suppressing virus replication and neutrophil-dependent tissue damage. Furthermore, the DCA and its nuclear farnesoid X receptor (FXR) agonist protect Syrian hamster from lethal SARS-CoV-2 infection. Moreover, we demonstrate that certain bile acids are reduced in the plasma of COVID-19 patients who developed moderate I/II disease compared with minor illness group. These findings uncover an unexpected mechanism by which virus-induced high fever increases host resistance to influenza virus and SARS-CoV-2 in a gut microbiota-dependent manner.
Project description:While a common symptom of influenza and coronavirus disease 2019 (COVID-19) is fever, its physiological role on host resistance to viral infection remains less clear. Here, we demonstrate that exposure of mice to the high ambient temperature of 36 °C increase host resistance to viral pathogens including influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). High heat-exposed mice increase basal body temperature over 38 °C to enable more bile acids production in a gut microbiota-dependent manner. The gut microbiota-derived deoxycholic acid (DCA) and its plasma membrane-bound receptor Takeda G-protein-coupled receptor 5 (TGR5) signaling increase host resistance to influenza virus infection by suppressing virus replication and neutrophil-dependent tissue damage. Furthermore, the DCA and its nuclear farnesoid X receptor (FXR) agonist protect Syrian hamster from lethal SARS-CoV-2 infection. Moreover, we demonstrate that certain bile acids are reduced in the plasma of COVID-19 patients who developed moderate I/II disease compared with minor illness group. These findings uncover an unexpected mechanism by which virus-induced high fever increases host resistance to influenza virus and SARS-CoV-2 in a gut microbiota-dependent manner.
Project description:Host cell lipids play a pivotal role in the pathogenesis of respiratory virus infection. However, a direct comparison of the lipidomic profile of influenza virus and rhinovirus infections is lacking. In this study, we first compared the lipid profile of influenza virus and rhinovirus infection in a bronchial epithelial cell line. Most lipid features were downregulated for both influenza virus and rhinovirus, especially for the sphingomyelin features. Pathway analysis showed that sphingolipid metabolism was the most perturbed pathway. Functional study showed that bacterial sphingomyelinase suppressed influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication, but promoted rhinovirus replication. These findings suggest that sphingomyelin pathway can be a potential target for antiviral therapy, but should be carefully evaluated as it has opposite effects on different respiratory viruses. Furthermore, the differential effect of sphingomyelinase on rhinovirus and influenza virus may explain the interference between rhinovirus and influenza virus infection.
Project description:Heldt2012 - Influenza Virus Replication
The model describes the life cycle of influenza A virus in a mammalian cell including the following steps: attachment of parental virions to the cell membrane, receptor-mediated endocytosis, fusion of the virus envelope with the endosomal membrane, nuclear import of vRNPs, viral transcription and replication, translation of the structural viral proteins, nuclear export of progeny vRNPs and budding of new virions. It also explicitly accounts for the stabilization of cRNA by viral polymerases and NP and the inhibition of vRNP activity by M1 protein binding. In short, the model focuses on the molecular mechanism that controls viral transcription and replication.
This model is described in the article:
Modeling the intracellular dynamics of influenza virus replication to understand the control of viral RNA synthesis.
Heldt FS, Frensing T, Reichl U.
J Virol.
Abstract:
Influenza viruses transcribe and replicate their negative-sense RNA genome inside the nucleus of host cells via three viral RNA species. In the course of an infection, these RNAs show distinct dynamics, suggesting that differential regulation takes place. To investigate this regulation in a systematic way, we developed a mathematical model of influenza virus infection at the level of a single mammalian cell. It accounts for key steps of the viral life cycle, from virus entry to progeny virion release, while focusing in particular on the molecular mechanisms that control viral transcription and replication. We therefore explicitly consider the nuclear export of viral genome copies (vRNPs) and a recent hypothesis proposing that replicative intermediates (cRNA) are stabilized by the viral polymerase complex and the nucleoprotein (NP). Together, both mechanisms allow the model to capture a variety of published data sets at an unprecedented level of detail. Our findings provide theoretical support for an early regulation of replication by cRNA stabilization. However, they also suggest that the matrix protein 1 (M1) controls viral RNA levels in the late phase of infection as part of its role during the nuclear export of viral genome copies. Moreover, simulations show an accumulation of viral proteins and RNA toward the end of infection, indicating that transport processes or budding limits virion release. Thus, our mathematical model provides an ideal platform for a systematic and quantitative evaluation of influenza virus replication and its complex regulation.
With the current parameter set, the model reproduces an infection at a multiplicity of infection (MOI) of 10. Figure 2A of the paper is reproduced here, with parameters kDegRnp and kSynP changed to zeros.
Initial conditions and parameter changes that were used to obtain specific figures in the article can be found in Table A2.
The model has the correct value for kAttLo as 4.55e-04. The value of this parameter mentioned as 4.55e-02 in Table 1 of the paper is incorrect. This is checked with the author.
This model is hosted on BioModels Database
and identified
by: MODEL1307270000
.
To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource
for published quantitative kinetic models
.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to the public
domain worldwide. Please refer to CC0 Public Domain
Dedication
for more information.
Project description:Classically, the cytidine deaminase APOBEC3G (A3G) exerts antiviral activity against transposable elements, retroviruses, and hepatitis B virus. However, we found earlier, that it also inhibits measles (MV), mumps (MuV) and respiratory syncytial virus (RSV), but the mechanism of inhibition remained unclear. Because A3G is present in RNA processing (P) bodies, where it is involved in the regulation of mRNA decay, we supposed that it may influence the expression of host cell factors, some of which may affect viral replication. Using a microarray we therefore assessed in Vero cells whether A3G expression influences the cellular gene expression. We found alterations indicating 844 up-regulated and 598 down-regulated transcripts (adjusted P values < 0.05). Of these trancripts 19 were up-regulated and 23 down-regulated by a factor of > 2. One of the down-regulated factors, MOSC2, appeared to support MV replication, since shRNA-mediated MOSC2 knock down reduced MV replication. In addition, two up-regulated factors, REDD1 and KDELR2, impaired MV replication when over-expressed in VeroREDD1 is a cellular inhibitor of mTORC1, a regulator of cellular homeostasis controlling cell growth and protein synthesis. Rapamycin also reduced MV replication confirming our findings with REDD1. The KDELR2 retains chaperons in the ER, which are required for proper folding and transport of MV glycoproteins to the cell surface, and thereby reduces MV glycoprotein expression at the cell surface, syncytium formation, and the formation of infectious virus.
Project description:Influenza A virus, with the limited coding capacity of 10 to 14 proteins, requires the host cellular machinery for many aspects of its life cycle. Knowledge of these host cell requirements not only reveals molecular pathways exploited by the virus or triggered by the immune system, but also provides further targets for antiviral drug development. To uncover novel pathways and key targets of influenza infection, we assembled a large amount of data from 12 cell-based gene-expression studies of influenza infection for an integrative network analysis. We systematically identified differentially expressed genes and gene co-expression networks induced by influenza infection. We revealed the dedicator of cytokinesis 5 (DOCK5) played potentially an important role for influenza virus replication. CRISPR/Cas9 knockout of DOCK5 reduced influenza virus replication, indicating that DOCK5 is a key regulator for the viral life cycle. DOCK5’s targets determined by the DOCK5 knockout experiments strongly validated the predicted gene signatures and networks. This study systematically uncovered and validated fundamental patterns of molecular responses, intrinsic structures of gene co-regulation, and novel key targets in influenza virus infection.
Project description:In order to identify the swine genes which play roles in the regulation of swine influenza A virus replication, the gene microarray was performed to explore the systematical host response to the swine H1N1/2009 influenza A virus infection in porcine cells.
Project description:Human infection with highly pathogenic H5N1 influenza virus causes severe respiratory diseases. Currently, the drugs against H5N1 are limited to virus-targeted inhibitors. However, drug resistance caused by these inhibitors is becoming a serious threat to global public health. An alternative strategy to reduce the resistance risk is to develop antiviral drugs targeting host cell proteins. In this study, we demonstrated that cytochrome c oxidase subunit 4 isoform 1 (COX41) of host cell plays an important role in H5N1 infection. Overexpression of COX41 promoted the viral replication, which was inhibited by silencing or knock-out the expression of COX41 in host cell. The viral ribonucleoproteins (vRNP) were retained in the nucleus after down-regulation of cellular COX41 expression. Strikingly, suppressing the expression of COX41 by lycorine, a small-molecule inhibitor isolated from Amaryllidaceae plants, resulted in the blockage of nuclear export of vRNP and inhibition of viral replication both in vitro and in vivo. Importantly, we did not obtain the resistant virus after culturing the virus with the continuous treatment of lycorine. Collectively, these results provided the direct evidence of the positive correlation between cellular COX41 levels and the influenza virus infection. Inhibition of COX41 expression in host cell may serve as a viable approach for anti-influenza therapy