Xinxia Peng

Lethal Influenza Virus Infection in Macaques Is Associated with Early Dysregulation of Inflammatory Related Genes

The enormous toll on human life during the 1918–1919 Spanish influenza pandemic is a constant reminder of the potential lethality of influenza viruses. With the declaration by the World Health Organization of a new H1N1 influenza virus pandemic, and with continued human cases of highly pathogenic H5N1 avian influenza virus infection, a better understanding of the host response to highly pathogenic influenza viruses is essential. To this end, we compared pathology and global gene expression profiles in bronchial tissue from macaques infected with either the reconstructed 1918 pandemic virus or the highly pathogenic avian H5N1 virus A/Vietnam/1203/04. Severe pathology was observed in respiratory tissues from 1918 virus-infected animals as early as 12 hours after infection, and pathology steadily increased at later time points. Although tissues from animals infected with A/Vietnam/1203/04 also showed clear signs of pathology early on, less pathology was observed at later time points, and there was evidence of tissue repair. Global transcriptional profiles revealed that specific groups of genes associated with inflammation and cell death were up-regulated in bronchial tissues from animals infected with the 1918 virus but down-regulated in animals infected with A/Vietnam/1203/04. Importantly, the 1918 virus up-regulated key components of the inflammasome, NLRP3 and IL-1β, whereas these genes were down-regulated by A/Vietnam/1203/04 early after infection. TUNEL assays revealed that both viruses elicited an apoptotic response in lungs and bronchi, although the response occurred earlier during 1918 virus infection. Our findings suggest that the severity of disease in 1918 virus-infected macaques is a consequence of the early up-regulation of cell death and inflammatory related genes, in which additive or synergistic effects likely dictate the severity of tissue damage.

Computational identification of hepatitis C virus associated microRNA-mRNA regulatory modules in human livers.

BackgroundHepatitis C virus (HCV) is a major cause of chronic liver disease by infecting over 170 million people worldwide. Recent studies have shown that microRNAs (miRNAs), a class of small non-coding regulatory RNAs, are involved in the regulation of HCV infection, but their functions have not been systematically studied. We propose an integrative strategy for identifying the miRNA-mRNA regulatory modules that are associated with HCV infection. This strategy combines paired expression profiles of miRNAs and mRNAs and computational target predictions. A miRNA-mRNA regulatory module consists of a set of miRNAs and their targets, in which the miRNAs are predicted to coordinately regulate the level of the target mRNA.ResultsWe simultaneously profiled the expression of cellular miRNAs and mRNAs across 30 HCV positive or negative human liver biopsy samples using microarray technology. We constructed a miRNA-mRNA regulatory network, and using a graph theoretical approach, identified 38 miRNA-mRNA regulatory modules in the network that were associated with HCV infection. We evaluated the direct miRNA regulation of the mRNA levels of targets in regulatory modules using previously published miRNA transfection data. We analyzed the functional roles of individual modules at the systems level by integrating a large-scale protein interaction network. We found that various biological processes, including some HCV infection related canonical pathways, were regulated at the miRNA level during HCV infection.ConclusionOur regulatory modules provide a framework for future experimental analyses. This report demonstrates the utility of our approach to obtain new insights into post-transcriptional gene regulation at the miRNA level in complex human diseases.

Unique Signatures of Long Noncoding RNA Expression in Response to Virus Infection and Altered Innate Immune Signaling

ABSTRACT Studies of the host response to virus infection typically focus on protein-coding genes. However, non-protein-coding RNAs (ncRNAs) are transcribed in mammalian cells, and the roles of many of these ncRNAs remain enigmas. Using next-generation sequencing, we performed a whole-transcriptome analysis of the host response to severe acute respiratory syndrome coronavirus (SARS-CoV) infection across four founder mouse strains of the Collaborative Cross. We observed differential expression of approximately 500 annotated, long ncRNAs and 1,000 nonannotated genomic regions during infection. Moreover, studies of a subset of these ncRNAs and genomic regions showed the following. (i) Most were similarly regulated in response to influenza virus infection. (ii) They had distinctive kinetic expression profiles in type I interferon receptor and STAT1 knockout mice during SARS-CoV infection, including unique signatures of ncRNA expression associated with lethal infection. (iii) Over 40% were similarly regulated in vitro in response to both influenza virus infection and interferon treatment. These findings represent the first discovery of the widespread differential expression of long ncRNAs in response to virus infection and suggest that ncRNAs are involved in regulating the host response, including innate immunity. At the same time, virus infection models provide a unique platform for studying the biology and regulation of ncRNAs. IMPORTANCE Most studies examining the host transcriptional response to infection focus only on protein-coding genes. However, there is growing evidence that thousands of non-protein-coding RNAs (ncRNAs) are transcribed from mammalian genomes. While most attention to the involvement of ncRNAs in virus-host interactions has been on small ncRNAs such as microRNAs, it is becoming apparent that many long ncRNAs (>200 nucleotides [nt]) are also biologically important. These long ncRNAs have been found to have widespread functionality, including chromatin modification and transcriptional regulation and serving as the precursors of small RNAs. With the advent of next-generation sequencing technologies, whole-transcriptome analysis of the host response, including long ncRNAs, is now possible. Using this approach, we demonstrated that virus infection alters the expression of numerous long ncRNAs, suggesting that these RNAs may be a new class of regulatory molecules that play a role in determining the outcome of infection. Most studies examining the host transcriptional response to infection focus only on protein-coding genes. However, there is growing evidence that thousands of non-protein-coding RNAs (ncRNAs) are transcribed from mammalian genomes. While most attention to the involvement of ncRNAs in virus-host interactions has been on small ncRNAs such as microRNAs, it is becoming apparent that many long ncRNAs (>200 nucleotides [nt]) are also biologically important. These long ncRNAs have been found to have widespread functionality, including chromatin modification and transcriptional regulation and serving as the precursors of small RNAs. With the advent of next-generation sequencing technologies, whole-transcriptome analysis of the host response, including long ncRNAs, is now possible. Using this approach, we demonstrated that virus infection alters the expression of numerous long ncRNAs, suggesting that these RNAs may be a new class of regulatory molecules that play a role in determining the outcome of infection.

MicroRNA Expression and Virulence in Pandemic Influenza Virus-Infected Mice

ABSTRACT The worst known H1N1 influenza pandemic in history resulted in more than 20 million deaths in 1918 and 1919. Although the underlying mechanism causing the extreme virulence of the 1918 influenza virus is still obscure, our previous functional genomics analyses revealed a correlation between the lethality of the reconstructed 1918 influenza virus (r1918) in mice and a unique gene expression pattern associated with severe immune responses in the lungs. Lately, microRNAs have emerged as a class of crucial regulators for gene expression. To determine whether differential expression of cellular microRNAs plays a role in the host response to r1918 infection, we compared the lung cellular “microRNAome” of mice infected by r1918 virus with that of mice infected by a nonlethal seasonal influenza virus, A/Texas/36/91. We found that a group of microRNAs, including miR-200a and miR-223, were differentially expressed in response to influenza virus infection and that r1918 and A/Texas/36/91 infection induced distinct microRNA expression profiles. Moreover, we observed significant enrichment in the number of predicted cellular target mRNAs whose expression was inversely correlated with the expression of these microRNAs. Intriguingly, gene ontology analysis revealed that many of these mRNAs play roles in immune response and cell death pathways, which are known to be associated with the extreme virulence of r1918. This is the first demonstration that cellular gene expression patterns in influenza virus-infected mice may be attributed in part to microRNA regulation and that such regulation may be a contributing factor to the extreme virulence of the r1918.

Infection with MERS-CoV causes lethal pneumonia in the common marmoset.

The availability of a robust disease model is essential for the development of countermeasures for Middle East respiratory syndrome coronavirus (MERS-CoV). While a rhesus macaque model of MERS-CoV has been established, the lack of uniform, severe disease in this model complicates the analysis of countermeasure studies. Modeling of the interaction between the MERS-CoV spike glycoprotein and its receptor dipeptidyl peptidase 4 predicted comparable interaction energies in common marmosets and humans. The suitability of the marmoset as a MERS-CoV model was tested by inoculation via combined intratracheal, intranasal, oral and ocular routes. Most of the marmosets developed a progressive severe pneumonia leading to euthanasia of some animals. Extensive lesions were evident in the lungs of all animals necropsied at different time points post inoculation. Some animals were also viremic; high viral loads were detected in the lungs of all infected animals, and total RNAseq demonstrated the induction of immune and inflammatory pathways. This is the first description of a severe, partially lethal, disease model of MERS-CoV, and as such will have a major impact on the ability to assess the efficacy of vaccines and treatment strategies as well as allowing more detailed pathogenesis studies.

Compression of next-generation sequencing reads aided by highly efficient de novo assembly

We present Quip, a lossless compression algorithm for next-generation sequencing data in the FASTQ and SAM/BAM formats. In addition to implementing reference-based compression, we have developed, to our knowledge, the first assembly-based compressor, using a novel de novo assembly algorithm. A probabilistic data structure is used to dramatically reduce the memory required by traditional de Bruijn graph assemblers, allowing millions of reads to be assembled very efficiently. Read sequences are then stored as positions within the assembled contigs. This is combined with statistical compression of read identifiers, quality scores, alignment information and sequences, effectively collapsing very large data sets to <15% of their original size with no loss of information. Availability: Quip is freely available under the 3-clause BSD license from http://cs.washington.edu/homes/dcjones/quip.

Lethal dissemination of H5N1 influenza virus is associated with dysregulation of inflammation and lipoxin signaling in a mouse model of infection

ABSTRACT Periodic outbreaks of highly pathogenic avian H5N1 influenza viruses and the current H1N1 pandemic highlight the need for a more detailed understanding of influenza virus pathogenesis. To investigate the host transcriptional response induced by pathogenic influenza viruses, we used a functional-genomics approach to compare gene expression profiles in lungs from 129S6/SvEv mice infected with either the fully reconstructed H1N1 1918 pandemic virus (1918) or the highly pathogenic avian H5N1 virus Vietnam/1203/04 (VN/1203). Although the viruses reached similar titers in the lung and caused lethal infections, the mean time of death was 6 days for VN/1203-infected animals and 9 days for mice infected with the 1918 virus. VN/1203-infected animals also exhibited an earlier and more potent inflammatory response. This response included induction of genes encoding components of the inflammasome. VN/1203 was also able to disseminate to multiple organs, including the brain, which correlated with changes in the expression of genes associated with hematological functions and lipoxin biogenesis and signaling. Both viruses elicited expression of type I interferon (IFN)-regulated genes in wild-type mice and to a lesser extent in mice lacking the type I IFN receptor, suggesting alternative or redundant pathways for IFN signaling. Our findings suggest that VN/1203 is more pathogenic in mice as a consequence of several factors, including the early and sustained induction of the inflammatory response, the additive or synergistic effects of upregulated components of the immune response, and inhibition of lipoxin-mediated anti-inflammatory responses, which correlated with the ability of VN/1203 to disseminate to extrapulmonary organs.

Virus-Host Interactions: From Systems Biology to Translational Research

Research embracing systems biology approaches and careful analysis of the critical host response has greatly expanded our understanding of infectious diseases. First-generation studies based on genomics and proteomics have made significant progress in establishing the foundation for network-based investigations on virus-host interactions. More recently, data from complementary high-throughput technologies, such as siRNA and microRNA screens and next-generation sequencing, are augmenting systems level analyses and are providing a more detailed and insightful multidimensional view of virus-host networks. Together with advances in data integration, systems biology approaches now have the potential to provide profound impacts on translational research, leading to the more rapid development of new therapeutics and vaccines for infectious diseases. In this review, we highlight new high-throughput technologies, a new philosophy for studying virus-host interactions, and discuss the potential of systems biology to facilitate bench-to-bedside research and create novel strategies to combat disease. Can we save the world using these approaches? Read on.

Next-Generation Sequencing Reveals HIV-1-Mediated Suppression of T Cell Activation and RNA Processing and Regulation of Noncoding RNA Expression in a CD4+ T Cell Line

ABSTRACT Next-generation sequencing (NGS) enables the highly sensitive measurement of whole transcriptomes. We report the first application to our knowledge of this technology to the analysis of RNA from a CD4+ T cell line infected with intact HIV. We sequenced the total mRNA from infected cells and detected differences in the expression of both host and viral mRNA. Viral reads represented a large portion of the total mapped sequencing reads: approximately 20% at 12 h postinfection (hpi) and 40% at 24 hpi. We also detected a small but significant suppression of T cell activation-related genes at 12 hpi. This suppression persisted and expanded by 24 hpi, providing new possible markers of virus-induced T cell cytopathology. By 24 hpi, the expression of over 50% of detectable host loci was also altered, indicating widespread alteration of host processes, including RNA processing, splicing, and transport to an extent not previously reported. In addition, next-generation sequencing provided insights into alternative viral RNA splice events and the expression of noncoding RNAs, including microRNA host genes. IMPORTANCE Recent advances in sequencing technology now allow the measurement of effectively all the RNA in a cell. This approach is especially useful for studying models of virus infection, as it allows the simultaneous measurement of both host and viral RNA. Using next-generation sequencing (NGS), we measured changes in total mRNA from a HIV-infected T cell line. To our knowledge, this is the first application of this technology to the investigation of HIV-host interactions involving intact HIV. We directly measured the amount of viral mRNA in infected cells and detected novel viral RNA splice variants and changes in the host expression of noncoding RNA species. We also detected small changes in T cell activation and other host processes during the early stages of viral replication that increased near the peak of viral replication, providing new candidate biomarkers of T cell death. Recent advances in sequencing technology now allow the measurement of effectively all the RNA in a cell. This approach is especially useful for studying models of virus infection, as it allows the simultaneous measurement of both host and viral RNA. Using next-generation sequencing (NGS), we measured changes in total mRNA from a HIV-infected T cell line. To our knowledge, this is the first application of this technology to the investigation of HIV-host interactions involving intact HIV. We directly measured the amount of viral mRNA in infected cells and detected novel viral RNA splice variants and changes in the host expression of noncoding RNA species. We also detected small changes in T cell activation and other host processes during the early stages of viral replication that increased near the peak of viral replication, providing new candidate biomarkers of T cell death.

Integrative Deep Sequencing of the Mouse Lung Transcriptome Reveals Differential Expression of Diverse Classes of Small RNAs in Response to Respiratory Virus Infection

ABSTRACT We previously reported widespread differential expression of long non-protein-coding RNAs (ncRNAs) in response to virus infection. Here, we expanded the study through small RNA transcriptome sequencing analysis of the host response to both severe acute respiratory syndrome coronavirus (SARS-CoV) and influenza virus infections across four founder mouse strains of the Collaborative Cross, a recombinant inbred mouse resource for mapping complex traits. We observed differential expression of over 200 small RNAs of diverse classes during infection. A majority of identified microRNAs (miRNAs) showed divergent changes in expression across mouse strains with respect to SARS-CoV and influenza virus infections and responded differently to a highly pathogenic reconstructed 1918 virus compared to a minimally pathogenic seasonal influenza virus isolate. Novel insights into miRNA expression changes, including the association with pathogenic outcomes and large differences between in vivo and in vitro experimental systems, were further elucidated by a survey of selected miRNAs across diverse virus infections. The small RNAs identified also included many non-miRNA small RNAs, such as small nucleolar RNAs (snoRNAs), in addition to nonannotated small RNAs. An integrative sequencing analysis of both small RNAs and long transcripts from the same samples showed that the results revealing differential expression of miRNAs during infection were largely due to transcriptional regulation and that the predicted miRNA-mRNA network could modulate global host responses to virus infection in a combinatorial fashion. These findings represent the first integrated sequencing analysis of the response of host small RNAs to virus infection and show that small RNAs are an integrated component of complex networks involved in regulating the host response to infection. IMPORTANCE Most studies examining the host transcriptional response to infection focus only on protein-coding genes. However, mammalian genomes transcribe many short and long non-protein-coding RNAs (ncRNAs). With the advent of deep-sequencing technologies, systematic transcriptome analysis of the host response, including analysis of ncRNAs of different sizes, is now possible. Using this approach, we recently discovered widespread differential expression of host long (>200 nucleotide [nt]) ncRNAs in response to virus infection. Here, the samples described in the previous report were again used, but we sequenced another fraction of the transcriptome to study very short (about 20 to 30 nt) ncRNAs. We demonstrated that virus infection also altered expression of many short ncRNAs of diverse classes. Putting the results of the two studies together, we show that small RNAs may also play an important role in regulating the host response to virus infection. Most studies examining the host transcriptional response to infection focus only on protein-coding genes. However, mammalian genomes transcribe many short and long non-protein-coding RNAs (ncRNAs). With the advent of deep-sequencing technologies, systematic transcriptome analysis of the host response, including analysis of ncRNAs of different sizes, is now possible. Using this approach, we recently discovered widespread differential expression of host long (>200 nucleotide [nt]) ncRNAs in response to virus infection. Here, the samples described in the previous report were again used, but we sequenced another fraction of the transcriptome to study very short (about 20 to 30 nt) ncRNAs. We demonstrated that virus infection also altered expression of many short ncRNAs of diverse classes. Putting the results of the two studies together, we show that small RNAs may also play an important role in regulating the host response to virus infection.