Project description:Due to the RNA nature of their genomes, influenza viruses have to utilize many RNA-binding proteins (RBPs) of both viral and host origin, for their replication. To uncover the comprehensive vRNA-host protein interactions, we performed affinity purification coupled with mass spectrometry (AP-MS) analysis of influenza vRNA complexes. The eight vRNA segments of H7N9 were transcribed and individually labeled with biotin in vitro and incubated with IAV virus-infected THP-1 cells, and vRNA complexes were enriched streptavidin magnetic beads and analyzed by mass spectrometry
Project description:Epidemics of influenza virus are of great challenges to the public concern. The lung inflammation and injury caused by excessive inflammatory cell infiltration into the lungs and overproduction of inflammatory mediators are major consequences during influenza virus infection. Neutrophils are vital for anti-microbial defense. However, the roles of neutrophils during viral infections are less clear. Furthermore, the molecular regulation of neutrophil fate and function at the viral infected sites is largely elusive. We found that BCL6 deficiency in neutrophils, but not in monocytes nor lung macrophages, attenuated host inflammation and morbidity following influenza infection. Mechanistically, BCL6 bound to the neutrophil gene loci involved in cellular apoptosis specifically at the site of infection. As such, BCL6 disruption resulted in increased expression of apoptotic genes in neutrophils in the respiratory tract, but not in the circulation nor bone marrow. Consequently, BCL6 deficiency promoted tissue neutrophil apoptosis. Our results have revealed a previously unappreciated role of BCL6 in modulating neutrophil apoptosis at the site of infection for the regulation of host disease development following viral 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.
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Project description:The SARS-CoV-2 coronavirus, which causes the COVID-19 pandemic, is one of the largest positive strand RNA viruses. Here we developed a simplified SPLASH assay and comprehensively mapped the in vivo RNA-RNA interactome of SARS-CoV-2 RNA during the viral life cycle. We observed canonical and alternative structures including 3’-UTR and 5’-UTR, frameshifting element (FSE) pseudoknot and genome cyclization in cells and in virions. We provide the first evidence of comprehensive interactions between Transcription Regulating Sequences (TRS-L and TRS-Bs), which facilitate discontinuous transcription. In addition, we find alternative short and long distance arches around FSE, forming a “high-order pseudoknot” embedding FSE, which might help ribosome stalling at frameshift sites. We found that during packaging, SARS-CoV-2 genome RNA undergoes compaction while genome domains remain stable and genome cyclization is weakened. Our data provides a structural basis for the regulation of replication, discontinuous transcription and translational frameshifting describes dynamics on RNA structures during life cycle of SARS-CoV-2, and will help to develop antiviral strategies.
Project description:In recent years, the roles of microRNAs playing in the regulation of influenza viruses replication caused researchers' much attenion. However, much work focused on the interactions between human, mice or chicken microRNAs with human or avian influenza viruses rather than the interactions of swine microRNAs and swine influenza viruses. To investigate the roles of swine microRNAs playing in the regulation of swine influenza A virus replication, the microRNA microarray was performed to identify which swine microRNAs were involved in swine H1N1/2009 influenza A virus infection.