PubMed Health⌕ Search

Biomedical subjects

Peter Palese

Publications and source records attributed to Peter Palese.

At least 19 recordsLinked to original sources
PubMed2006

Severe acute respiratory syndrome coronavirus open reading frame (ORF) 3b, ORF 6, and nucleocapsid proteins function as interferon antagonists.

The severe acute respiratory syndrome coronavirus (SARS-CoV) is highly pathogenic in humans, with a death rate near 10%. This high pathogenicity suggests that SARS-CoV has developed mechanisms to overcome the host innate immune response. It has now been determined that SARS-CoV open reading frame (ORF) 3b, ORF 6, and N proteins antagonize interferon, a key component of the innate immune response. All three proteins inhibit the expression of beta interferon (IFN-beta), and further examination revealed that these SARS-CoV proteins inhibit a key protein necessary for the expression of IFN-beta, IRF-3. N protein dramatically inhibited expression from an NF-kappaB-responsive promoter. All three proteins were able to inhibit expression from an interferon-stimulated response element (ISRE) promoter after infection with Sendai virus, while only ORF 3b and ORF 6 proteins were able to inhibit expression from the ISRE promoter after treatment with interferon. This indicates that N protein inhibits only the synthesis of interferon, while ORF 3b and ORF 6 proteins inhibit both interferon synthesis and signaling. ORF 6 protein, but not ORF 3b or N protein, inhibited nuclear translocation but not phosphorylation of STAT1. Thus, it appears that these three interferon antagonists of SARS-CoV inhibit the interferon response by different mechanisms.

Apoptosis↗
PubMed2006

Genomic analysis of increased host immune and cell death responses induced by 1918 influenza virus.

The influenza pandemic of 1918-19 was responsible for about 50 million deaths worldwide. Modern histopathological analysis of autopsy samples from human influenza cases from 1918 revealed significant damage to the lungs with acute, focal bronchitis and alveolitis associated with massive pulmonary oedema, haemorrhage and rapid destruction of the respiratory epithelium. The contribution of the host immune response leading to this severe pathology remains largely unknown. Here we show, in a comprehensive analysis of the global host response induced by the 1918 influenza virus, that mice infected with the reconstructed 1918 influenza virus displayed an increased and accelerated activation of host immune response genes associated with severe pulmonary pathology. We found that mice infected with a virus containing all eight genes from the pandemic virus showed marked activation of pro-inflammatory and cell-death pathways by 24 h after infection that remained unabated until death on day 5. This was in contrast with smaller host immune responses as measured at the genomic level, accompanied by less severe disease pathology and delays in death in mice infected with influenza viruses containing only subsets of 1918 genes. The results indicate a cooperative interaction between the 1918 influenza genes and show that study of the virulence of the 1918 influenza virus requires the use of the fully reconstructed virus. With recent concerns about the introduction of highly pathogenic avian influenza viruses into humans and their potential to cause a worldwide pandemic with disastrous health and economic consequences, a comprehensive understanding of the global host response to the 1918 virus is crucial. Moreover, understanding the contribution of host immune responses to virulent influenza virus infections is an important starting point for the identification of prognostic indicators and the development of novel antiviral therapies.

Animals↗
PubMed2006

The guinea pig as a transmission model for human influenza viruses.

The severity of epidemic and pandemic influenza outbreaks is dictated in part by the efficiency with which the causative strain transmits between human hosts. The mechanisms underlying influenza virus spread are poorly understood, in part because of the lack of a convenient animal model to study this phenomenon. Indeed, despite extremely efficient transmission among humans and virulence in the mouse model, we have shown that even the 1918 pandemic influenza virus does not transmit between mice. We therefore evaluated the guinea pig as a model mammalian host for influenza virus. Using the recent human isolate A/Panama/2007/99 (Pan/99) (H3N2) virus, we found that guinea pigs were highly susceptible to infection with the unadapted virus (ID(50) = 5 plaque-forming units). Pan/99 virus grew to high titers in the upper respiratory tract and was shed in nasal washings of infected animals. Moreover, influenza virus was transmitted from infected guinea pigs to noninfected guinea pigs housed in the same cage, an adjacent cage, and a cage placed 91 cm away. Our results demonstrate that influenza virus can pass between guinea pigs by means of droplet spread and thereby establish the suitability of the guinea pig as a model host for influenza virus transmission studies.

Animals↗
PubMed2006

Engineered viral vaccine constructs with dual specificity: avian influenza and Newcastle disease.

Avian influenza viruses of the H5 and H7 hemagglutinin subtypes, and Newcastle disease virus (NDV), are important pathogens in poultry worldwide. Specifically, the highly pathogenic H5N1 avian influenza virus is a particular threat because it has now occurred in more than 40 countries on several continents. Inasmuch as most chickens worldwide are vaccinated with a live NDV vaccine, we embarked on the development of vaccine prototypes that would have dual specificity and would allow a single immunization against both avian influenza and Newcastle disease. Using reverse genetics, we constructed a chimeric avian influenza virus that expressed the ectodomain of the hemagglutinin-neuraminidase gene of NDV instead of the neuraminidase protein of the H5N1 avian influenza virus. Our second approach to creating a bivalent vaccine was based on expressing the ectodomain of an H7 avian influenza virus hemagglutinin in a fusogenic and attenuated NDV background. The insertion into the NDV genome of the foreign gene (containing only its ectodomain, with the transmembrane and cytoplasmic domains derived from the F protein of NDV) resulted in a chimeric virus with enhanced incorporation of the foreign protein into virus particles. A single immunization of chickens with this improved vaccine prototype virus induced not only a 90% protection against an H7N7 highly pathogenic avian influenza virus, but also complete immunity against a highly virulent NDV. We propose that chimeric constructs should be developed for convenient, affordable, and effective vaccination against avian influenza and Newcastle disease in chickens and other poultry.

Animals↗
PubMed2006

Sequence analysis and receptor specificity of the hemagglutinin of a recent influenza H2N2 virus isolated from chicken in North America.

Influenza viruses bind host cells following an interaction between the viral hemagglutinin (HA) protein and host cell sialylated glycoproteins and glycolipids. Differences in binding affinities of the HAs for different types of sialic acid linkages (alpha2-3 vs. alpha2-6) contribute to determining the host range of an influenza virus. The ability of an avian influenza virus HA to bind the human form of the receptor may be one requirement for an avian virus to propagate in the human population. In this paper, we describe the characterization of the HA from an H2N2 virus isolated from a Pennsylvania chicken farm in 2004. Sequence analysis revealed that this HA is a member of the Eurasian clade, and receptor binding studies show that it maintains its specificity for the avian influenza virus alpha2-3 linked sialic acid receptor.

Amino Acid Sequence↗
PubMed2006

Influenza A virus PB1-F2 protein contributes to viral pathogenesis in mice.

The influenza virus PB1-F2 protein is a novel protein previously shown to be involved in induction of cell death. Here we characterize the expression and the function of the protein within the context of influenza viral infection in tissue culture and a mouse model. We show that the C-terminal region of the protein can be expressed from a downstream initiation codon and is capable of interaction with the full-length protein. Using this knowledge, we generated influenza viruses knocked out for the expression of PB1-F2 protein and its downstream truncation products. Knocking out the PB1-F2 protein had no effect on viral replication in tissue culture but diminished virus pathogenicity and mortality in mice. The viruses replicated to similar levels in mouse lungs by day 3 postinfection, suggesting that the knockout did not impair viral replication. However, while the PB1-F2 knockout viruses were cleared after day 5, the wild-type viruses were detectable in mouse lungs until day 7, implying that expression of PB1-F2 resulted in delayed clearance of the viruses by the host immune system. Based on our findings and on the fact that the PB1 genomic segment was always newly introduced into some pandemic influenza viruses of the last century, we speculate that the PB1-F2 protein plays an important role in pathogenesis of influenza virus infection and may be an important contributor to pathogenicity of pandemic influenza viruses.

Animals↗
PubMed2006

7a protein of severe acute respiratory syndrome coronavirus inhibits cellular protein synthesis and activates p38 mitogen-activated protein kinase.

It was recently shown that the 7a protein of severe acute respiratory syndrome coronavirus induces biochemical changes associated with apoptosis. In this study, the mechanism by which the 7a protein induces apoptosis was examined. The 7a protein was tested for the ability to inhibit cellular gene expression because several proapoptotic viral proteins with this function have previously been identified. 7a protein inhibited expression of luciferase from an mRNA construct that specifically measures translation, whereas inhibitors of transcription and nucleocytoplasmic transport did not. The inhibition of translation and other cellular processes of gene expression have been associated with the induction of a stress response in cells. Western blot analysis using phosphospecific antibodies indicated that 7a protein activated p38 mitogen-activated protein kinase (MAPK), but not c-Jun N-terminal protein kinase/stress-activated protein kinase. Taken together, these data indicate that the induction of apoptosis by the 7a protein may be related to its ability to inhibit cellular translation and activate p38 MAPK.

Apoptosis↗
PubMed2006

Making better influenza virus vaccines?

Killed and live influenza virus vaccines are effective in preventing and curbing the spread of disease, but new technologies such as reverse genetics could be used to improve them and to shorten the lengthy process of preparing vaccine seed viruses. By taking advantage of these new technologies, we could develop live vaccines that would be safe, cross-protective against variant strains, and require less virus per dose than conventional vaccines. Furthermore, pandemic vaccines against highly virulent strains such as the H5N1 virus can only be generated by reverse genetics techniques. Other technologic breakthroughs should result in effective adjuvants for use with killed and live vaccines, increasing the number of available doses. Finally, universal influenza virus vaccines seem to be within reach. These new strategies will be successful if they are supported by regulatory agencies and if a robust market for influenza virus vaccines against inter-pandemic and pandemic threats is made and sustained.

Adjuvants, Immunologic↗
PubMed2005

Glycan microarray analysis of the hemagglutinins from modern and pandemic influenza viruses reveals different receptor specificities.

Influenza A virus specificity for the host is mediated by the viral surface glycoprotein hemagglutinin (HA), which binds to receptors containing glycans with terminal sialic acids. Avian viruses preferentially bind to alpha2-3-linked sialic acids on receptors of intestinal epithelial cells, whereas human viruses are specific for the alpha2-6 linkage on epithelial cells of the lungs and upper respiratory tract. To define the receptor preferences of a number of human and avian H1 and H3 viruses, including the 1918 H1N1 pandemic strains, their hemagglutinins were analyzed using a recently described glycan array. The array, which contains 200 carbohydrates and glycoproteins, not only revealed clear differentiation of receptor preferences for alpha2-3 and/or alpha2-6 sialic acid linkage, but could also detect fine differences in HA specificity, such as preferences for fucosylation, sulfation and sialylation at positions 2 (Gal) and 3 (GlcNAc, GalNAc) of the terminal trisaccharide. For the two 1918 HA variants, the South Carolina (SC) HA (with Asp190, Asp225) bound exclusively alpha2-6 receptors, while the New York (NY) variant, which differed only by one residue (Gly225), had mixed alpha2-6/alpha2-3 specificity, especially for sulfated oligosaccharides. Only one mutation of the NY variant (Asp190Glu) was sufficient to revert the HA receptor preference to that of classical avian strains. Thus, the species barrier, as defined by the receptor specificity preferences of 1918 human viruses compared to likely avian virus progenitors, can be circumvented by changes at only two positions in the HA receptor binding site. The glycan array thus provides highly detailed profiles of influenza receptor specificity that can be used to map the evolution of new human pathogenic strains, such as the H5N1 avian influenza.

Amino Acid Sequence↗
PubMed2005

Characterization of the reconstructed 1918 Spanish influenza pandemic virus.

The pandemic influenza virus of 1918-1919 killed an estimated 20 to 50 million people worldwide. With the recent availability of the complete 1918 influenza virus coding sequence, we used reverse genetics to generate an influenza virus bearing all eight gene segments of the pandemic virus to study the properties associated with its extraordinary virulence. In stark contrast to contemporary human influenza H1N1 viruses, the 1918 pandemic virus had the ability to replicate in the absence of trypsin, caused death in mice and embryonated chicken eggs, and displayed a high-growth phenotype in human bronchial epithelial cells. Moreover, the coordinated expression of the 1918 virus genes most certainly confers the unique high-virulence phenotype observed with this pandemic virus.

Animals↗
PubMed2005

Influenza virus PB1-F2 protein induces cell death through mitochondrial ANT3 and VDAC1.

The influenza virus PB1-F2 is an 87-amino acid mitochondrial protein that previously has been shown to induce cell death, although the mechanism of apoptosis induction has remained unclear. In the process of characterizing its mechanism of action we found that the viral PB1-F2 protein sensitizes cells to apoptotic stimuli such as tumor necrosis factor alpha, as demonstrated by increased cleavage of caspase 3 substrates in PB1-F2-expressing cells. Moreover, treatment of purified mouse liver mitochondria with recombinant PB1-F2 protein resulted in cytochrome c release, loss of the mitochondrial membrane potential, and enhancement of tBid-induced mitochondrial permeabilization, suggesting a possible mechanism for the observed cellular sensitization to apoptosis. Using glutathione-S-transferase pulldowns with subsequent mass spectrometric analysis, we identified the mitochondrial interactors of the PB1-F2 protein and showed that the viral protein uniquely interacts with the inner mitochondrial membrane adenine nucleotide translocator 3 and the outer mitochondrial membrane voltage-dependent anion channel 1, both of which are implicated in the mitochondrial permeability transition during apoptosis. Consistent with this interaction, blockers of the permeability transition pore complex (PTPC) inhibited PB1-F2-induced mitochondrial permeabilization. Based on our findings, we propose a model whereby the proapoptotic PB1-F2 protein acts through the mitochondrial PTPC and may play a role in the down-regulation of the host immune response to infection.

Journal Article↗
PubMed2005

An unconventional NLS is critical for the nuclear import of the influenza A virus nucleoprotein and ribonucleoprotein.

Replication of the RNAs of influenza virus occurs in the nucleus of infected cells. The nucleoprotein (NP) has been shown to be important for the import of the viral RNA into the nucleus and has been proposed to contain at least three different nuclear localization signals (NLSs). Here, an import assay in digitonin-permeabilized cells was used to further define the contribution of these NLSs. Mutation of the unconventional NLS impaired the nuclear import of the NP. A peptide bearing the unconventional NLS could inhibit the nuclear import of the NP in this import assay and prevent the NP-karyopherin alpha interaction in a binding assay confirming the crucial role of this signal. Interestingly, a peptide containing the SV40 T antigen NLS was unable to inhibit the nuclear import of NP or the NP-karyopherin alpha interaction, suggesting that the NP and the SV40 T antigen do not share a common binding site on karyopherin alpha. We also investigated the question of which NLS(s) is/are necessary for the viral ribonucleoprotein complex to enter the nucleus. We found that the peptide containing the unconventional NLS efficiently inhibited the nuclear import of the ribonucleoprotein complexes. This finding suggests that the unconventional NLS is the major signal necessary not only for the nuclear transport of free NP but also for the import of the ribonucleoprotein complexes. Finally, viral replication could be specifically inhibited by a membrane-permeable peptide containing the unconventional NLS, confirming the crucial role of this signal during the replicative cycle of the virus.

Active Transport, Cell Nucleus↗
PubMed2005

Nuclear localization of the Nipah virus W protein allows for inhibition of both virus- and toll-like receptor 3-triggered signaling pathways.

The Nipah virus V and W proteins, which are encoded by the P gene via RNA editing, have a common N-terminal domain but unique C-terminal domains. They localize to the cytoplasm and nucleus, respectively, and have both been shown to function as inhibitors of JAK/STAT signaling. Here we report that V and W proteins also block virus activation of the beta interferon (IFN-beta) promoter and the IFN regulatory factor 3 (IRF3)-responsive IFN-stimulated gene 54 promoter. Surprisingly, only W protein shows strong inhibition of promoter activation in response to stimulation of Toll-like receptor 3 (TLR3) by extracellular double-stranded RNA. This activity is dependent on the nuclear localization of W protein. Within the unique C-terminal domain of W protein, we have identified a nuclear localization signal (NLS) that requires basic residues at positions 439, 440, and 442. This NLS is responsible for mediating the preferential interaction of W protein with karyopherin-alpha 3 and karyopherin-alpha 4. Nuclear localization of W protein therefore enables it to target both virus and TLR3 pathways, whereas the cytoplasmic V protein is restricted to inhibiting the virus pathway. We propose that this discrepancy is in part due to the V protein being less able to block signaling in response to the kinase, TBK-1, whereas both V and W can prevent promoter activation in response to IKKepsilon. We demonstrate that, when the TLR3 pathway is stimulated, the levels of phosphorylated IRF3 are reduced in the presence of W protein but not V protein, confirming the differential effects of these proteins and illustrating that W protein-mediated inhibition is due to a loss of active IRF3.

Amino Acid Sequence↗
PubMed2005

Attenuation of equine influenza viruses through truncations of the NS1 protein.

Equine influenza is a common disease of the horse, causing significant morbidity worldwide. Here we describe the establishment of a plasmid-based reverse genetics system for equine influenza virus. Utilizing this system, we generated three mutant viruses encoding carboxy-terminally truncated NS1 proteins. We have previously shown that a recombinant human influenza virus lacking the NS1 gene (delNS1) could only replicate in interferon (IFN)-incompetent systems, suggesting that the NS1 protein is responsible for IFN antagonist activity. Contrary to previous findings with human influenza virus, we found that in the case of equine influenza virus, the length of the NS1 protein did not correlate with the level of attenuation of that virus. With equine influenza virus, the mutant virus with the shortest NS1 protein turned out to be the least attenuated. We speculate that the basis for attenuation of the equine NS1 mutant viruses generated is related to their level of NS1 protein expression. Our findings show that the recombinant mutant viruses are impaired in their ability to inhibit IFN production in vitro and they do not replicate as efficiently as the parental recombinant strain in embryonated hen eggs, in MDCK cells, or in vivo in a mouse model. Therefore, these attenuated mutant NS1 viruses may have potential as candidates for a live equine influenza vaccine.

Animals↗
PubMed2005

A single amino acid substitution in 1918 influenza virus hemagglutinin changes receptor binding specificity.

The receptor binding specificity of influenza viruses may be important for host restriction of human and avian viruses. Here, we show that the hemagglutinin (HA) of the virus that caused the 1918 influenza pandemic has strain-specific differences in its receptor binding specificity. The A/South Carolina/1/18 HA preferentially binds the alpha2,6 sialic acid (human) cellular receptor, whereas the A/New York/1/18 HA, which differs by only one amino acid, binds both the alpha2,6 and the alpha2,3 sialic acid (avian) cellular receptors. Compared to the conserved consensus sequence in the receptor binding site of avian HAs, only a single amino acid at position 190 was changed in the A/New York/1/18 HA. Mutation of this single amino acid back to the avian consensus resulted in a preference for the avian receptor.

Amino Acid Substitution↗
PubMed2005

Pathogenicity of influenza viruses with genes from the 1918 pandemic virus: functional roles of alveolar macrophages and neutrophils in limiting virus replication and mortality in mice.

The Spanish influenza pandemic of 1918 to 1919 swept the globe and resulted in the deaths of at least 20 million people. The basis of the pulmonary damage and high lethality caused by the 1918 H1N1 influenza virus remains largely unknown. Recombinant influenza viruses bearing the 1918 influenza virus hemagglutinin (HA) and neuraminidase (NA) glycoproteins were rescued in the genetic background of the human A/Texas/36/91 (H1N1) (1918 HA/NA:Tx/91) virus. Pathogenesis experiments revealed that the 1918 HA/NA:Tx/91 virus was lethal for BALB/c mice without the prior adaptation that is usually required for human influenza A H1N1 viruses. The increased mortality of 1918 HA/NA:Tx/91-infected mice was accompanied by (i) increased (>200-fold) viral replication, (ii) greater influx of neutrophils into the lung, (iii) increased numbers of alveolar macrophages (AMs), and (iv) increased protein expression of cytokines and chemokines in lung tissues compared with the levels seen for control Tx/91 virus-infected mice. Because pathological changes in AMs and neutrophil migration correlated with lung inflammation, we assessed the role of these cells in the pathogenesis associated with 1918 HA/NA:Tx/91 virus infection. Neutrophil and/or AM depletion initiated 3 or 5 days after infection did not have a significant effect on the disease outcome following a lethal 1918 HA/NA:Tx/91 virus infection. By contrast, depletion of these cells before a sublethal infection with 1918 HA/NA:Tx/91 virus resulted in uncontrolled virus growth and mortality in mice. In addition, neutrophil and/or AM depletion was associated with decreased expression of cytokines and chemokines. These results indicate that a human influenza H1N1 virus possessing the 1918 HA and NA glycoproteins can induce severe lung inflammation consisting of AMs and neutrophils, which play a role in controlling the replication and spread of 1918 HA/NA:Tx/91 virus after intranasal infection of mice.

Animals↗
PubMed2005

A novel paramyxovirus?

In public databases, we identified sequences reported as human genes expressed in kidney mesangial cells. The similarity of these genes to paramyxovirus matrix, fusion, and phosphoprotein genes suggests that they are derived from a novel paramyxovirus. These genes are sufficiently unique to suggest the existence of a novel paramyxovirus genus.

Amino Acid Sequence↗