pinecone/core-2020-05-10-deduplication huggingface dataset:
Binding Properties, Cell Delivery, and Gene Transfer of Adenoviral Penton Base Displaying Bacteriophage

AbstractThe penton base of adenovirus mediates viral attachment to integrin receptors and particle internalisation, properties that can be exploited to reengineer prokariotic viruses for the infection of mammalian cells. We report that filamentous phage displaying either the full-length penton base gene or a central region of 107 amino acids on their surface were able to bind, internalise, and transduce mammalian cells expressing integrin receptors. Both phage bound αvβ3, αvβ5, α3β1, and α5β1 integrin subtypes. Cell-binding was shown by electron microscopy; internalisation was investigated by immunofluorescence and confirmed by micropanning. As it has been described for adenovirus, pharmacologic disruption of phosphoinositide-30H kinase, but not of myosin light-chain kinase, inhibited phage internalisation. Recombinant phage encoding an eukaryotic expression cassette was able to mediate gene expression in mammalian cells. Taken together, these data open insights for the exploit of recombinant phage for integrin-targeted gene delivery
Antigenic and Genetic Characterization of Swine Influenza A (H1N1) Viruses Isolated from Pneumonia Patients in The Netherlands

AbstractIt is generally believed that pigs can serve as an intermediate host for the transmission of avian influenza viruses to humans or as mixing vessels for the generation of avian–human reassortant viruses. Here we describe the antigenic and genetic characterization of two influenza A (H1N1) viruses, which were isolated in The Netherlands from two patients who suffered from pneumonia. Both viruses proved to be antigenically and genetically similar to avian-like swine influenza A (H1N1) viruses which currently circulate in European pigs. It is concluded that European swine H1N1 viruses can infect humans directly, causing serious disease without the need for any reassortment event
Syncytium Formation Amplifies Apoptotic Signals: A New View on Apoptosis in HIV Infection in Vitro

AbstractInfection of CD4+ cells with HIV in vitro causes extensive cytopathicity. The mechanism that underlies this process is unclear and conflicting data exist regarding whether cytotoxicity is due to necrosis or apoptosis. It was previously reported and is shown here that the coculture of HIV glycoprotein-expressing cells with CD4+ cells results in apoptosis within several hours. This study demonstrates that apoptosis did not occur in single cells and was mediated neither by CD4 nor by coreceptor signaling, indicating that apoptosis was not induced by intra- or intercellular glycoprotein–receptor interaction. Detection of apoptosis required cell-to-cell fusion and undetectable levels of apoptotic cell death were substantially amplified upon syncytium formation. Similar results were obtained with syncytium-forming cultures of measles virus glycoprotein-expressing cells. These findings indicate that the apoptotic cell death observed in cultures of HIV and other syncytium-forming viruses is primarily due to amplification of background apoptosis in the wake of cell-to-cell fusion
HIV-1 Nef Blocks Transport of MHC Class I Molecules to the Cell Surface Via a PI 3-Kinase-Dependent Pathway

AbstractHIV causes a chronic infection by evading immune eradication. A key element of HIV immune escape is the HIV-1 Nef protein. Nef causes a reduction in the level of cell surface major histocompatibility complex class I (MHC-I) protein expression, thus protecting HIV-infected cells from anti-HIV cytotoxic T lymphocyte (CTL) recognition and killing. Nef also reduces cell surface levels of the HIV receptor, CD4, by accelerating endocytosis. We show here that endocytosis is not required for Nef-mediated downmodulation of MHC-I molecules. The main effect of Nef is to block transport of MHC-I molecules to the cell surface, leading to accumulation in intracellular organelles. Furthermore, the effect of Nef on MHC-I molecules (but not on CD4) requires phosphoinositide 3-kinase (PI 3-kinase) activity. We propose that Nef diverts MHC-1 proteins into a PI 3-kinase-dependent transport pathway that prevents expression on the cell surface
The Effect of Human bcl-2 and bcl-X Genes on Dengue Virus-Induced Apoptosis in Cultured Cells

AbstractInfection of dengue viruses (DENs) can cause human dengue fever, hemorrhagic fever, or shock syndrome. Although DEN-induced apoptosis has been implicated in pathogenesis of the DEN-related diseases, the underlying mechanism remains largely unexplored. In this study, we investigated the effect of ectopic expression of human bcl-2 and bcl-X genes on DEN-induced apoptosis in cultured cells. We employed a human isolate of DEN serotype 2 (DEN-2), PL046, which not only caused cell-cycle arrest in the G1 phase but also induced apoptosis in infected baby hamster kidney (BHK-21) cells, murine neuroblastoma N18 cells, and human neuronal NT-2 cells. Our results reveal that overexpression of bcl-2 in fibroblast-like BHK-21 cells, although not inhibiting virus yields, delayed the process of DEN-induced apoptosis, thereby permitting surviving cells to become persistently infected. In contrast, stable bcl-2 expression in neuronal N18 cells failed to block DEN-induced apoptosis. On the other hand, Bcl-XL, expressed predominantly in the nervous system, appeared to delay DEN's killing effect in neuronal N18 cells but not in fibroblast-like BHK-21 cells. In addition, inducible expression bcl-Xs, despite its proapoptotic property in other reported system, was found to merely accelerate cell death in DEN-infected N18 but not in infected BHK-21 cells. Thus, through studying the effect of human bcl-2-related genes, our results suggest that DEN infection may trigger target cells to undergo morphologically similar but biochemically distinct apoptotic pathways in a cell-specific manner
A Simian Human Immunodeficiency Virus with a Nonfunctional Vpu (ΔvpuSHIVKU-1bMC33) Isolated from a Macaque with NeuroAIDS Has Selected for Mutations in Env and Nef That Contributed to Its Pathogenic Phenotype

AbstractPrevious studies have shown that passage of nonpathogenic SHIV-4 through a series of macaques results in the selection of variants of the virus that are capable of causing rapid subtotal loss of CD4+ T cells and AIDS within 6–8 months following inoculation into pig-tailed macaques. Using a pathogenic variant of SHIV-4 known as SHIVKU-1bMC33, we reported that a mutant of this virus with the majority of the vpu deleted was still capable of causing profound CD4+ T cell loss and neuroAIDS in pig-tailed macaques (McCormick-Davis et al., 2000, Virology 272, 112–116). In this study, we have analyzed the tissue-specific changes in the env and nef in one macaque that developed neuroAIDS (macaque 50 O) and in three macaques that developed only a moderate or no significant loss of CD4+ T cells and no neurological disease (macaques 50 Y, 20220, 20228) following inoculation with ΔvpuSHIVKU-1bMC33. Sequence analysis of the gp120 region of env isolated from lymphoid tissues (lymph node and spleen) of macaques 50 Y, 20220, and 20228 revealed no consensus amino acid substitutions. In contrast, analysis of the gp120 sequences isolated from lymphoid and CNS tissues (parietal cortex, basal ganglia, and pons) of macaque 50 O revealed numerous amino acid substitutions. The significance of the amino acid substitutions in gp120 was supported by neutralization assays which showed that the virus isolated from the lymph node of macaque 50 O was neutralization resistant compared to the parental SHIVKU-1bMC33. Analysis of changes in the nef gene from macaque 50 O revealed in-frame deletions in Nef that ranged from 4 to 13 amino acids in length, whereas the nef genes isolated from the other three macaques revealed no deletions or consensus amino acid substitutions. Inoculation of the virus isolated from the lymph node of the macaque which developed neuroAIDS, SHIV50OLNV, into four pig-tailed macaques resulted in a severe loss of the circulating CD4+ T cells within 2 weeks postinoculation, which was maintained for up to 20 weeks postinoculation, confirming that this virus had indeed become more pathogenic in pig-tailed macaques. Taken together, these observations suggest that ΔvpuSHIVKU-1bMC33 has a low pathogenic phenotype in macaques but that individual pig-tailed macaques can select for additional mutations within the Env and Nef which can compensate for the lack of an intact Vpu and ultimately increase its pathogenicity
Phenotypic and Functional Characteristics of FIV Infection in the Bone Marrow Stroma

AbstractHuman (HIV) and feline (FIV) immunodeficiency virus has been reported to infect bone marrow (BM) and stroma, followed by a loss in normal hematopoiesis. However, the magnitude and nature of HIV and FIV pathogenesis of the BM/stromal network are still unclear. In the current studies, pathogenesis of stromal cells was evaluated using the FIV model. Fourteen specific-pathogen-free cats inoculated with the four different strains (FIVUK8, FIVBang, FIVShi, or FIVPet) were monitored for FIV infection in the peripheral blood mononuclear cells (PBMC), BM cells, and stromal cells. All inoculated cats became positive for FIV in the PBMC by 7 weeks p.i. and 13 of 14 cats had FIV in the BM cells by 7–13 weeks p.i. FIV was detected in macrophages and stromal fibroblasts from FIVUK8-, FIVBang-, and FIVShi-infected cats but not from FIVPet-infected cats and only transiently in cells from FIVShi-infected cats. The ability of the supernatants from FIV-infected stromal cells to sustain the growth of uninfected BM cells was decreased 35–46% when compared to the supernatants from uninfected stromal cells. These results suggest that the FIV infection of the stroma alters normal hempatopoietic function(s) and that the infected stromal cells can also serve as a reservoir for FIV infection
The Basic Loop of the RNase H Domain of MLV RT Is Important Both for RNase H and for Polymerase Activity

AbstractEscherichia coli RNase H has a basic extension that is involved in binding nucleic acid substrates. This basic extension is present in the RNase H of Moloney murine leukemia virus reverse transcriptase (MLV RT), but has been deleted from the RNase H of HIV-1 RT. Previous work showed that removing the basic loop from MLV RT (the mutant is called ΔC) blocked viral replication; however, ΔC MLV RT retained RNase H activity in an in situ gel assay. We prepared recombinant ΔC MLV RT and compared its activity to wild-type MLV RT. The ΔC mutant is impaired in both polymerase and RNase H activity; the pattern of defects suggests that the basic loop is involved in the binding of MLV RT to a heteropolymeric template-primer
Pathogenicity of a Natural Recombinant Associated with Ageratum Yellow Vein Disease: Implications for Geminivirus Evolution and Disease Aetiology

AbstractYellow vein disease of Ageratum conyzoides is caused by a viral DNA complex consisting of the genomic component (DNA A) of the monopartite begomovirus Ageratum yellow vein virus (AYVV, family: Geminiviridae) and a small satellite-like DNA β component. AYVV DNA A is unable to induce symptoms in this host alone but can systemically infect A. conyzoides in which it accumulates to low levels. Here, we demonstrate that the yellow vein phenotype can also be produced by co-inoculating A. conyzoides with AYVV DNA A and recDNA-Aβ17, a naturally occurring recombinant of approximately the same size as DNA β that contains sequences from both DNA A and DNA β. Symptoms induced by DNA A and recDNA-Aβ17 in A. conyzoides and Nicotiana glutinosa are qualitatively similar to those associated with DNA A and DNA β although milder. Recombination between DNA A and DNA β to produce a chimera resembling recDNA-Aβ17 was observed after whitefly transmission of the disease in A. conyzoides. Hence, such recombination events are likely to occur frequently, implying that recombinants will normally be associated with this type of disease complex in the field. Possible implications of these findings for the evolution of begomoviruses and the aetiology of their diseases are discussed
Hepatitis C Virus Protein Expression Induces Apoptosis in HepG2 Cells

AbstractThe mechanisms of hepatocyte death and the events that lead to a high rate of chronic liver disease in patients infected with hepatitis C virus are not known. We established a HCV replication system in HepG2 cell culture and utilized this model to address the effect of HCV proteins on HepG2 cell growth and viability. After transfection of HepG2 cells with full-length RNA, a truncated RNA, or an antisense RNA, cell proliferation and cell viability were analyzed by thymidine uptake and the trypan blue exclusion method, respectively. Full-length RNA transfected HepG2 cells showed a decrease in cell proliferation and viability compared to cells transfected with HCV truncated RNA and antisense RNA control. A subset of cells expressing HCV proteins underwent apoptosis as documented by morphological studies, ultrastructural analysis, cell cycle analysis by flow cytometry, terminal transferase enzyme mediated end labeling of DNA, and DNA laddering. This study suggests that expression of HCV proteins can lead to cell death by apoptosis, which may be an important event in the pathogenesis of chronic hepatitis C virus infection in humans
Potyviral Helper-Component Proteinase Expressed in Transgenic Plants Enhances Titers of Potato Leaf Roll Virus but Does Not Alleviate Its Phloem Limitation

AbstractCoinfection of Nicotiana benthamiana with Potato virus A (PVA, a potyvirus) and Potato leaf-roll virus (PLRV, a luteovirus) induces a synergistic interaction manifested by enhanced titers of PLRV. The helper component proteinase (HC-Pro) of potyviruses is involved in viral vascular movement and suppression of an antiviral defense mechanism in plants. Data of our study showed that accumulation of PLRV in transgenic N. benthamiana expressing the PVA HC-Pro was enhanced on average by 4.5-fold, as compared to a 6.0-fold enhancement in wild-type N. benthamiana plants doubly infected with PVA and PLRV. Enhancement of PLRV accumulation was directly proportional to the concentration of the HC-Pro in leaves. In the HC-Pro-transgenic plants and wild-type plants, PLRV was almost exclusively confined to the phloem, but the HC-Pro-transgenic plants had a fourfold greater number of PLRV-infected cells within the phloem tissues, as revealed by immunohistochemical staining. In the leaves doubly infected with PLRV and PVA, PLRV was found to exit the phloem in 25.0% of the veins, infecting all types of leaf cells, but, on average, PLRV accumulation was not enhanced more than by sixfold at the whole-leaf level. Therefore, potyviral/luteoviral synergism seems to be based on two mechanisms. One of them is mediated by the HC-Pro and increases luteovirus accumulation without allowing detectable egress from vascular tissue. The other mechanism probably depends on additional potyviral proteins and alleviates the normal phloem limitation of PLRV
Characterization of Less Pathogenic Infectious Molecular Clones Derived from Acute-Pathogenic SHIV-89.6P Stock Virus

AbstractFor a better understanding of the acute pathogenicity of SHIV-89.6P stock virus, which induces prominent CD4 cell loss within a month after inoculation in monkeys, we have constructed four infectious molecular clones (cl 18, cl 64, cl 69, and cl 71). Cl 64, cl 69, and cl 71, like the parental virus, showed a high in vitro replication ability and a pathogenic-like effect (CD4 downmodulation) in a monkey CD4+ cell line, whereas cl 18 showed a lower replication ability and could not downmodulate CD4. Cl 64, which has characteristics similar to those of the parental virus in vitro, was inoculated into four rhesus monkeys. All monkeys showed a plasma viral load similar to that of the parental virus with a peak at 2 weeks after inoculation. However, the viral load gradually decreased and the virus failed to cause an AIDS-like disease in infected monkeys, but it induced a strong antiviral antibody response. These results demonstrate the polyclonal nature of the parental SHIV-89.6P virus stock and demonstrate that cl 64, aside from its high replicability, may differ qualitatively from the parental virus
Absence of Genetic Diversity Reduction in the HIV-1 Integrated Proviral LTR Sequence Population during Successful Combination Therapy

AbstractWe report the integrated proviral LTR sequence variation in four patients on highly active antiretroviral therapy (HAART). Integrated proviral fragments of LTR taken from four time points were PCR amplified from PBMCs and 10 to 12 individual clones were sequenced for each time point. Intrasample genetic distances and phylogenetic reconstruction of all LTR sequences demonstrated that 1–2 years of successful HAART did not significantly reduce the genetic repertoire of the integrated reservoir of HIV-1
Genetic Diversity of Beak and Feather Disease Virus Detected in Psittacine Species in Australia

AbstractThe complete nucleotide (nt) sequence of eight isolates of beak and feather disease virus (BFDV) obtained from a range of psittacine species with psittacine beak and feather disease (PBFD) from throughout Australia were compared with the sequences of two BFDV isolates previously reported from Australia (BFDV-AUS) and America (BFDV-USA), respectively. All isolates had the same basic structure including the position of the open reading frames, the hairpin structure between ORF1 and ORF2, the nonanucleotide motif (TAGTATTAC) therein, the three motifs of Rep protein encoded from ORF1 and involved in rolling circle replication, and the P-loop motif previously described, but the genome size of the eight isolates ranged from 1992 to 2018 nt. Overall nt identity of the isolates compared to BFDV-AUS ranged from 84 to 97%; the variation was due to a combination of point mutations and a number of deletions and insertions ranging from 1 to 17 nt in size detected in both coding and noncoding regions. The identity of the nt sequence of ORF2 compared to BFDV-AUS varied from 80 to 99%, while the identity of the deduced amino acid sequences varied from 73 to 99%. Phylogenetic analysis grouped the isolates into four clusters but there were no apparent regional differences or differences related to the psittacine species of origin. While seven ORFs with the potential to encode proteins greater than 8.7 kDa were detected in the BFDV-AUS isolate described previously, only three of these ORFs were detected in all 10 BFDV isolates for which sequence data were available. The three ORFs were ORF1 that presumably encodes the Rep protein, ORF2 presumably the major capsid protein, and the ORF previously designated ORF5. The ORF5 was of two size classes in different isolates, 303 and 474 nt, and only the first 303 nt of the viruses with an ORF of 474 nt were common to the other isolates
Human Herpesvirus 8 Interaction with Target Cells Involves Heparan Sulfate

AbstractHuman herpesvirus 8 (HHV-8) or Kaposi's sarcoma associated herpesvirus (KSHV) is associated with Kaposi's sarcoma and primary effusion lymphoma. In vivo, HHV-8 DNA and transcripts have been detected in B cells, endothelial cells, macrophages, and epithelial cells. HHV-8 infects a variety of cell lines of human and animal origin, leading to latent or abortive infection. This study shows that the broad cellular tropism of HHV-8 may be in part due to its interaction with the ubiquitous host cell surface molecule, heparan sulfate (HS). This conclusion is based on the following findings: (i) HHV-8 infection of human foreskin fibroblast (HFF) cells was inhibited in a dose-dependent manner by soluble heparin, a glycosaminoglycan closely related to HS. Chondroitin sulfates A and C did not inhibit HHV-8 infection. (ii) Enzymatic removal of HFF cell surface HS with heparinase I and III reduced HHV-8 infection. (iii) Soluble heparin inhibited the binding of radiolabeled HHV-8 to human B cell lines, embryonic kidney epithelial (293) cells, and HFF cells, suggesting interference at the virus attachment stage. (iv) Cell surface adsorbed HHV-8 was displaced by soluble heparin. (v) Radiolabeled HHV-8 also bound to wild-type HS expressing Chinese hamster ovary (CHO-K1) cells. In contrast, binding of virus to mutant CHO cells deficient in HS was significantly reduced. These data show that the γ2 herpesvirus HHV-8, similar to some members of α, β, and γ2 herpesviruses, adsorbs to cells by binding to cell surface HS-like moieties. Heparin did not completely prevent the binding and infectivity of HHV-8, suggesting that HHV-8 interactions with HS could be the first set of ligand–receptor interaction leading to the binding with one or more host cell receptors essential for the subsequent viral entry process
Reactivation of Feline Foamy Virus from a Chronically Infected Feline Renal Cell Line by Trichostatin A

AbstractAlthough acute infection of feline foamy virus (FeFV) is normally highly cytopathogenic in Crandell feline kidney (CRFK) cells, a noncytopathic persistent infection was established in the cells after cocultivation of the initially infected cells with uninfected cells four times. To investigate reactivation of persistent infection, CRFK cells chronically infected with FeFV were treated with trichostatin A (TA), a histone deacetylase inhibitor. TA induced higher FeFV production from the Coleman strain carrier culture and also induced marked syncytium formation. In contrast, human foamy virus, which contains less homologous long terminal repeat (LTR) and putative internal promoter (IP) sequences, persistently infecting baby hamster kidney cells was not reactivated by TA. The Sammy-1 strain of FeFV, from which a part of the U3 region in the LTR is naturally deleted, showed less reactivation. The Coleman LTR promoter-based β-Gal-expressing plasmid was activated in the persistently Coleman-infected cells in the presence of TA, whereas the Sammy-1 LTR was not activated. Furthermore, the amounts of Gag protein expressed did not change in the presence or absence of TA. Because the putative IP region was very similar between the two strains, the initiation by TA is relatively specific for LTR sequences, and, therefore, histone deacetylation is at least in part responsible for reactivation of FeFV from carrier cell culture
Induction of Type-Specific Neutralizing Antibodies by Capsomeres of Human Papillomavirus Type 33

AbstractThe immunogenicity of capsomeres of human papillomavirus type 33 was evaluated in a dose–response analysis. Capsomeres were obtained free of capsids by expression of L1 carrying the single point mutation C427S. Neutralizing antibodies were detected using an in vitro pseudoinfection assay. Capsomeres induced type-specific, neutralizing antibodies in mice even in the absence of adjuvant. The neutralization titers of immune sera raised without adjuvant were 10- to 20-fold lower than those of antisera to virus-like particles, but virtually identical using Freund's adjuvant. These data indicate that capsomeres may substitute for virus-like particles in future vaccines when used with an adjuvant appropriate for human vaccination