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Peter Palese

Publications and source records attributed to Peter Palese.

At least 37 records · Page 2Linked to original sources
PubMed2004

Pathogenicity and immunogenicity of influenza viruses with genes from the 1918 pandemic virus.

The 1918 influenza A H1N1 virus caused the worst pandemic of influenza ever recorded. To better understand the pathogenesis and immunity to the 1918 pandemic virus, we generated recombinant influenza viruses possessing two to five genes of the 1918 influenza virus. Recombinant influenza viruses possessing the hemagglutinin (HA), neuraminidase (NA), matrix (M), nonstructural (NS), and nucleoprotein (NP) genes or any recombinant virus possessing both the HA and NA genes of the 1918 influenza virus were highly lethal for mice. Antigenic analysis by hemagglutination inhibition (HI) tests with ferret and chicken H1N1 antisera demonstrated that the 1918 recombinant viruses antigenically most resembled A/Swine/Iowa/30 (Sw/Iowa/30) virus but differed from H1N1 viruses isolated since 1930. HI and virus neutralizing (VN) antibodies to 1918 recombinant and Sw/Iowa/30 viruses in human sera were present among individuals born before or shortly after the 1918 pandemic. Mice that received an intramuscular immunization of the homologous or Sw/Iowa/30-inactivated vaccine developed HI and VN antibodies to the 1918 recombinant virus and were completely protected against lethal challenge. Mice that received A/PR/8/34, A/Texas/36/91, or A/New Caledonia/20/99 H1N1 vaccines displayed partial protection from lethal challenge. In contrast, control-vaccinated mice were not protected against lethal challenge and displayed high virus titers in respiratory tissues. Partial vaccine protection mediated by baculovirus-expressed recombinant HA vaccines suggest common cross-reactive epitopes on the H1 HA. These data suggest a strategy of vaccination that would be effective against a reemergent 1918 or 1918-like virus.

Animals↗
PubMed2004

Structure of the uncleaved human H1 hemagglutinin from the extinct 1918 influenza virus.

The 1918 "Spanish" influenza pandemic represents the largest recorded outbreak of any infectious disease. The crystal structure of the uncleaved precursor of the major surface antigen of the extinct 1918 virus was determined at 3.0 angstrom resolution after reassembly of the hemagglutinin gene from viral RNA fragments preserved in 1918 formalin-fixed lung tissues. A narrow avian-like receptor-binding site, two previously unobserved histidine patches, and a less exposed surface loop at the cleavage site that activates viral membrane fusion reveal structural features primarily found in avian viruses, which may have contributed to the extraordinarily high infectivity and mortality rates observed during 1918.

Amino Acid Sequence↗
PubMed2004

Interferon antagonist proteins of influenza and vaccinia viruses are suppressors of RNA silencing.

Homology-dependent RNA silencing occurs in many eukaryotic cells. We reported recently that nodaviral infection triggers an RNA silencing-based antiviral response (RSAR) in Drosophila, which is capable of a rapid virus clearance in the absence of expression of a virus-encoded suppressor. Here, we present further evidence to show that the Drosophila RSAR is mediated by the RNA interference (RNAi) pathway, as the viral suppressor of RSAR inhibits experimental RNAi initiated by exogenous double-stranded RNA and RSAR requires the RNAi machinery. We demonstrate that RNAi also functions as a natural antiviral immunity in mosquito cells. We further show that vaccinia virus and human influenza A, B, and C viruses each encode an essential protein that suppresses RSAR in Drosophila. The vaccinia and influenza viral suppressors, E3L and NS1, are distinct double-stranded RNA-binding proteins and essential for pathogenesis by inhibiting the mammalian IFN-regulated innate antiviral response. We found that the double-stranded RNA-binding domain of NS1, implicated in innate immunity suppression, is both essential and sufficient for RSAR suppression. These findings provide evidence that mammalian virus proteins can inhibit RNA silencing, implicating this mechanism as a nucleic acid-based antiviral immunity in mammalian cells.

Animals↗
PubMed2004

Influenza: old and new threats.

Influenza remains an important disease in humans and animals. In contrast to measles, smallpox and poliomyelitis, influenza is caused by viruses that undergo continuous antigenic change and that possess an animal reservoir. Thus, new epidemics and pandemics are likely to occur in the future, and eradication of the disease will be difficult to achieve. Although it is not clear whether a new pandemic is imminent, it would be prudent to take into account the lessons we have learned from studying different human and animal influenza viruses. Specifically, reconstruction of the genes of the 1918 pandemic virus and studies on their contribution to virulence will be important steps toward understanding the biological capabilities of this lethal virus. Increasing the availability of new antiviral drugs and developing superior vaccines will provide us with better approaches to control influenza and to have a positive impact on disease load. A concern is that the imposition of new rules for working with infectious influenza viruses under high security and high containment conditions will stifle scientific progress. The complex questions of what makes an influenza virus transmissible from one human to another and from one species to another, as well as how the immune system interacts with the virus, will require the active collaboration and unencumbered work of many scientific groups.

Animals↗
PubMed2004

Nipah virus V and W proteins have a common STAT1-binding domain yet inhibit STAT1 activation from the cytoplasmic and nuclear compartments, respectively.

In previous reports it was demonstrated that the Nipah virus V and W proteins have interferon (IFN) antagonist activity due to their ability to block signaling from the IFN-alpha/beta receptor (J. J. Rodriguez, J. P. Parisien, and C. M. Horvath, J. Virol. 76:11476-11483, 2002; M. S. Park et al., J. Virol. 77:1501-1511, 2003). The V, W, and P proteins are all encoded by the same viral gene and share an identical 407-amino-acid N-terminal region but have distinct C-terminal sequences. We now show that the P protein also has anti-IFN function, confirming that the common N-terminal domain is responsible for the antagonist activity. Truncation of this N-terminal domain revealed that amino acids 50 to 150 retain the ability to block IFN and to bind STAT1, a key component of the IFN signaling pathway. Subcellular localization studies demonstrate that the V and P proteins are predominantly cytoplasmic whereas the W protein is localized to the nucleus. In all cases, STAT1 colocalizes with the corresponding Nipah virus protein. These interactions are sufficient to inhibit STAT1 activation, as demonstrated by the lack of STAT1 phosphorylation on tyrosine 701 in IFN-stimulated cells expressing P, V, or W. Therefore, despite their common STAT1-binding domain, the Nipah virus V and P proteins act by retaining STAT1 in the cytoplasm while the W protein sequesters STAT1 in the nucleus, creating both a cytoplasmic and a nuclear block for STAT1. We also show that the IFN antagonist activity of the P protein is not as strong as that of V or W, perhaps explaining why Nipah virus has evolved to express these two edited products.

Animals↗
PubMed2004

Induction of cellular immune responses to simian immunodeficiency virus gag by two recombinant negative-strand RNA virus vectors.

A recombinant Newcastle disease virus (rNDV) expressing simian immunodeficiency virus (SIV) Gag protein (rNDV/SIVgag) was generated. The rNDV/SIVgag virus induced Gag-specific cellular immune responses in mice, leading to a specific anti-Gag antiviral immunity. This was evidenced by the inhibition of growth of recombinant vaccinia virus expressing an identical Gag antigen (rVac/SIVgag) but not of wild-type vaccinia virus in rNDV/SIVgag-immunized mice. Among intravenous, intraperitoneal, or intranasal immunization routes, intranasal administration induced the strongest protective response against challenge with rVac/SIVgag. We further demonstrated that these immune responses were greatly enhanced after booster immunization with recombinant influenza viruses expressing immunogenic portions of SIV Gag. The magnitude of the protective immune response correlated with the levels of cellular immune responses to Gag, which were still evident 9 weeks after immunization. These results suggest that rNDV and influenza virus vectors are suitable candidate vaccines against AIDS as well as against other infectious diseases.

Amino Acid Sequence↗
PubMed2003

Trafficking of viral genomic RNA into and out of the nucleus: influenza, Thogoto and Borna disease viruses.

Most RNA viruses that lack a DNA phase replicate in the cytoplasm. However, several negative-stranded RNA viruses such as influenza, Thogoto, and Borna disease viruses replicate their RNAs in the nucleus, taking advantage of the host cell's nuclear machinery. A challenge faced by these viruses is the trafficking of viral components into and out of the nucleus through the nuclear membrane. The genomic RNAs of these viruses associate with proteins to form large complexes called viral ribonucleoproteins (vRNPs), which exceed the size limit for passive diffusion through the nuclear pore complex (NPC). To insure efficient transport across the nuclear membrane, these viruses use nuclear import and export signals exposed on the vRNPs. These signals recruit the cellular import and export complexes, which are responsible for the translocation of the vRNPs through the NPC. The ability to control the direction of vRNP trafficking throughout the viral life cycle is critical. Various mechanisms, ranging from simple post-translational modification to complex, sequential masking-and-exposure of localization signals, are used to insure the proper movement of the vRNPs.

Active Transport, Cell Nucleus↗
PubMed2003

Activation of tumor antigen-specific cytotoxic T lymphocytes (CTLs) by human dendritic cells infected with an attenuated influenza A virus expressing a CTL epitope derived from the HER-2/neu proto-oncogene.

The development of cancer vaccines requires approaches to induce expansion and functional differentiation of tumor antigen-specific cytotoxic T lymphocyte (CTL) effectors which posses cytolytic capability and produce cytokines. Efficient induction of such cells is hindered by the poor immunogenicity of tumor antigens and by the poor transduction efficiency of dendritic cells (DCs) with current nonreplicating vectors. We have investigated the use of influenza A virus, a potent viral inducer of CTLs, as a vector expressing the immunodominant HER-2 CTL epitope KIF (E75). For this purpose, an attenuated influenza A/PR8/34 virus with a truncated nonstructural (NS1) gene was generated containing the E75 epitope in its neuraminidase protein (KIF-NS virus). Stimulation of peripheral blood mononuclear cells from healthy donors and of tumor-associated lymphocytes from ovarian and breast cancer patients with DCs infected with KIF-NS virus (KIF-NS DC) induced CTLs that specifically recognized the peptide KIF and HER-2-expressing tumors in cytotoxicity assays and secreted gamma interferon (IFN-gamma) and interleukin-2 at recall with peptide. Priming with KIF-NS DCs increased the number of E75(+) CD45RO(+) cells by more than 10-fold compared to nonstimulated cells. In addition, KIF-NS virus induced high levels of IFN-alpha in DCs. This is the first report demonstrating induction of human epitope-specific CTLs against a tumor-associated antigen with a live attenuated recombinant influenza virus vector. Such vectors may provide a novel approach for tumor antigen delivery, lymphocyte activation, and differentiation in human cancer vaccine development.

Amino Acid Sequence↗
PubMed2003

The Ebola virus VP35 protein inhibits activation of interferon regulatory factor 3.

The Ebola virus VP35 protein was previously found to act as an interferon (IFN) antagonist which could complement growth of influenza delNS1 virus, a mutant influenza virus lacking the influenza virus IFN antagonist protein, NS1. The Ebola virus VP35 could also prevent the virus- or double-stranded RNA-mediated transcriptional activation of both the beta IFN (IFN-beta) promoter and the IFN-stimulated ISG54 promoter (C. Basler et al., Proc. Natl. Acad. Sci. USA 97:12289-12294, 2000). We now show that VP35 inhibits virus infection-induced transcriptional activation of IFN regulatory factor 3 (IRF-3)-responsive mammalian promoters and that VP35 does not block signaling from the IFN-alpha/beta receptor. The ability of VP35 to inhibit this virus-induced transcription correlates with its ability to block activation of IRF-3, a cellular transcription factor of central importance in initiating the host cell IFN response. We demonstrate that VP35 blocks the Sendai virus-induced activation of two promoters which can be directly activated by IRF-3, namely, the ISG54 promoter and the ISG56 promoter. Further, expression of VP35 prevents the IRF-3-dependent activation of the IFN-alpha4 promoter in response to viral infection. The inhibition of IRF-3 appears to occur through an inhibition of IRF-3 phosphorylation. VP35 blocks virus-induced IRF-3 phosphorylation and subsequent IRF-3 dimerization and nuclear translocation. Consistent with these observations, Ebola virus infection of Vero cells activated neither transcription from the ISG54 promoter nor nuclear accumulation of IRF-3. These data suggest that in Ebola virus-infected cells, VP35 inhibits the induction of antiviral genes, including the IFN-beta gene, by blocking IRF-3 activation.

Animals↗
PubMed2003

Chimeric influenza A viruses with a functional influenza B virus neuraminidase or hemagglutinin.

Reassortment of influenza A and B viruses has never been observed in vivo or in vitro. Using reverse genetics techniques, we generated recombinant influenza A/WSN/33 (WSN) viruses carrying the neuraminidase (NA) of influenza B virus. Chimeric viruses expressing the full-length influenza B/Yamagata/16/88 virus NA grew to titers similar to that of wild-type influenza WSN virus. Recombinant viruses in which the cytoplasmic tail or the cytoplasmic tail and the transmembrane domain of the type B NA were replaced with those of the type A NA were impaired in tissue culture. This finding correlates with reduced NA content in virions. We also generated a recombinant influenza A virus expressing a chimeric hemagglutinin (HA) protein in which the ectodomain is derived from type B/Yamagata/16/88 virus HA, whereas both the cytoplasmic and the transmembrane domains are derived from type A/WSN virus HA. This A/B chimeric HA virus did not grow efficiently in MDCK cells. However, after serial passage we obtained a virus population that grew to titers as high as wild-type influenza A virus in MDCK cells. One amino acid change in position 545 (H545Y) was found to be responsible for the enhanced growth characteristics of the passaged virus. Taken together, we show here that the absence of reassortment between influenza viruses belonging to different A and B types is not due to spike glycoprotein incompatibility at the level of the full-length NA or of the HA ectodomain.

Amino Acid Substitution↗
PubMed2003

Newcastle disease virus V protein is a determinant of host range restriction.

It has been demonstrated that the V protein of Newcastle disease virus (NDV) functions as an alpha/beta interferon (IFN-alpha/beta) antagonist (M. S. Park, M. L. Shaw, J. Muñoz-Jordan, J. F. Cros, T. Nakaya, N. Bouvier, P. Palese, A. García-Sastre, and C. F. Basler, J. Virol. 77:1501-1511, 2003). We now show that the NDV V protein plays an important role in host range restriction. In order to study V functions in vivo, recombinant NDV (rNDV) mutants, defective in the expression of the V protein, were generated. These rNDV mutants grow poorly in both embryonated chicken eggs and chicken embryo fibroblasts (CEFs) compared to the wild-type (wt) rNDV. However, insertion of the NS1 gene of influenza virus A/PR8/34 into the NDV V(-) genome [rNDV V(-)/NS1] restores impaired growth to wt levels in embryonated chicken eggs and CEFs. These data indicate that for viruses infecting avian cells, the NDV V protein and the influenza NS1 protein are functionally interchangeable, even though there are no sequence similarities between the two proteins. Interestingly, in human cells, the titer of wt rNDV is 10 times lower than that of rNDV V(-)/NS1. Correspondingly, the level of IFN secreted by human cells infected with wt rNDV is much higher than that secreted by cells infected with the NS1-expressing rNDV. This suggests that the IFN antagonist activity of the NDV V protein is species specific. Finally, the NDV V protein plays an important role in preventing apoptosis in a species-specific manner. The rNDV defective in V induces apoptotic cell death more rapidly in CEFs than does wt rNDV. Taken together, these data suggest that the host range of NDV is limited by the ability of its V protein to efficiently prevent innate host defenses, such as the IFN response and apoptosis.

Amino Acid Sequence↗
PubMed2003

Newcastle disease virus (NDV)-based assay demonstrates interferon-antagonist activity for the NDV V protein and the Nipah virus V, W, and C proteins.

We have generated a recombinant Newcastle disease virus (NDV) that expresses the green fluorescence protein (GFP) in infected chicken embryo fibroblasts (CEFs). This virus is interferon (IFN) sensitive, and pretreatment of cells with chicken alpha/beta IFN (IFN-alpha/beta) completely blocks viral GFP expression. Prior transfection of plasmid DNA induces an IFN response in CEFs and blocks NDV-GFP replication. However, transfection of known inhibitors of the IFN-alpha/beta system, including the influenza A virus NS1 protein and the Ebola virus VP35 protein, restores NDV-GFP replication. We therefore conclude that the NDV-GFP virus could be used to screen proteins expressed from plasmids for the ability to counteract the host cell IFN response. Using this system, we show that expression of the NDV V protein or the Nipah virus V, W, or C proteins rescues NDV-GFP replication in the face of the transfection-induced IFN response. The V and W proteins of Nipah virus, a highly lethal pathogen in humans, also block activation of an IFN-inducible promoter in primate cells. Interestingly, the amino-terminal region of the Nipah virus V protein, which is identical to the amino terminus of Nipah virus W, is sufficient to exert the IFN-antagonist activity. In contrast, the anti-IFN activity of the NDV V protein appears to be located in the carboxy-terminal region of the protein, a region implicated in the IFN-antagonist activity exhibited by the V proteins of mumps virus and human parainfluenza virus type 2.

Animals↗
PubMed2003

Induction of protective immunity against malaria by priming-boosting immunization with recombinant cold-adapted influenza and modified vaccinia Ankara viruses expressing a CD8+-T-cell epitope derived from the circumsporozoite protein of Plasmodium yoelii.

We immunized mice with an attenuated (cold-adapted) influenza virus followed by an attenuated vaccinia virus (modified vaccinia virus Ankara), both expressing a CD8(+)-T-cell epitope derived from malaria sporozoites. This vaccination regimen elicited high levels of protection against malaria. This is the first time that the vaccine efficacy of a recombinant cold-adapted influenza virus vector expressing a foreign antigen has been evaluated.

Adaptation, Physiological↗
PubMed2002

Existing antivirals are effective against influenza viruses with genes from the 1918 pandemic virus.

The 1918 influenza pandemic caused more than 20 million deaths worldwide. Thus, the potential impact of a re-emergent 1918 or 1918-like influenza virus, whether through natural means or as a result of bioterrorism, is of significant concern. The genetic determinants of the virulence of the 1918 virus have not been defined yet, nor have specific clinical prophylaxis and/or treatment interventions that would be effective against a re-emergent 1918 or 1918-like virus been identified. Based on the reported nucleotide sequences, we have reconstructed the hemagglutinin (HA), neuraminidase (NA), and matrix (M) genes of the 1918 virus. Under biosafety level 3 (agricultural) conditions, we have generated recombinant influenza viruses bearing the 1918 HA, NA, or M segments. Strikingly, recombinant viruses possessing both the 1918 HA and 1918 NA were virulent in mice. In contrast, a control virus with the HA and NA from a more recent human isolate was unable to kill mice at any dose tested. The recombinant viruses were also tested for their sensitivity to U.S. Food and Drug Administration-approved antiinfluenza virus drugs in vitro and in vivo. Recombinant viruses possessing the 1918 NA or both the 1918 HA and 1918 NA were inhibited effectively in both tissue culture and mice by the NA inhibitors, zanamivir and oseltamivir. A recombinant virus possessing the 1918 M segment was inhibited effectively both in tissue culture and in vivo by the M2 ion-channel inhibitors amantadine and rimantadine. These data suggest that current antiviral strategies would be effective in curbing the dangers of a re-emergent 1918 or 1918-like virus.

Amantadine↗
PubMed2002

Cellular transcriptional profiling in influenza A virus-infected lung epithelial cells: the role of the nonstructural NS1 protein in the evasion of the host innate defense and its potential contribution to pandemic influenza.

The NS1 protein of influenza A virus contributes to viral pathogenesis, primarily by enabling the virus to disarm the host cell type IFN defense system. We examined the downstream effects of NS1 protein expression during influenza A virus infection on global cellular mRNA levels by measuring expression of over 13,000 cellular genes in response to infection with wild-type and mutant viruses in human lung epithelial cells. Influenza A/PR/8/34 virus infection resulted in a significant induction of genes involved in the IFN pathway. Deletion of the viral NS1 gene increased the number and magnitude of expression of cellular genes implicated in the IFN, NF-kappaB, and other antiviral pathways. Interestingly, different IFN-induced genes showed different sensitivities to NS1-mediated inhibition of their expression. A recombinant virus with a C-terminal deletion in its NS1 gene induced an intermediate cellular mRNA expression pattern between wild-type and NS1 knockout viruses. Most significantly, a virus containing the 1918 pandemic NS1 gene was more efficient at blocking the expression of IFN-regulated genes than its parental influenza A/WSN/33 virus. Taken together, our results suggest that the cellular response to influenza A virus infection in human lung cells is significantly influenced by the sequence of the NS1 gene, demonstrating the importance of the NS1 protein in regulating the host cell response triggered by virus infection.

Cell Line↗
PubMed2002

Functional replacement of the carboxy-terminal two-thirds of the influenza A virus NS1 protein with short heterologous dimerization domains.

The NS1 protein of influenza A/WSN/33 virus is a 230-amino-acid-long protein which functions as an interferon alpha/beta (IFN-alpha/beta) antagonist by preventing the synthesis of IFN during viral infection. In tissue culture, the IFN inhibitory function of the NS1 protein has been mapped to the RNA binding domain, the first 73 amino acids. Nevertheless, influenza viruses expressing carboxy-terminally truncated NS1 proteins are attenuated in mice. Dimerization of the NS1 protein has previously been shown to be essential for its RNA binding activity. We have explored the ability of heterologous dimerization domains to functionally substitute in vivo for the carboxy-terminal domains of the NS1 protein. Recombinant influenza viruses were generated that expressed truncated NS1 proteins of 126 amino acids, fused to 28 or 24 amino acids derived from the dimerization domains of either the Saccharomyces cerevisiae PUT3 or the Drosophila melanogaster Ncd (DmNcd) proteins. These viruses regained virulence and lethality in mice. Moreover, a recombinant influenza virus expressing only the first 73 amino acids of the NS1 protein was able to replicate in mice lacking three IFN-regulated antiviral enzymes, PKR, RNaseL, and Mx, but not in wild-type (Mx-deficient) mice, suggesting that the attenuation was mainly due to an inability to inhibit the IFN system. Remarkably, a virus with an NS1 truncated at amino acid 73 but fused to the dimerization domain of DmNcd replicated and was also highly pathogenic in wild-type mice. These results suggest that the main biological function of the carboxy-terminal region of the NS1 protein of influenza A virus is the enhancement of its IFN antagonist properties by stabilizing the NS1 dimeric structure.

Animals↗
PubMed2002

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.

The influenza A virus NS1 protein, a virus-encoded alpha/beta interferon (IFN-alpha/beta) 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.

Adenoviruses, Human↗