bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distinct Biology of Kaposi’s Sarcoma-Associated Herpesvirus from Primary Lesions and Body Cavity Lymphomas
Authors: Friborg Jacques , Kong Wing-Pui , Flowers C. Clay , Flowers Scarlett L. , Sun Yongnian , Foreman Kimberly E. , Nickoloff Brian J. , Nabel Gary J. 
Published: December 2019

ABSTRACT
The DNA sequence for Kaposi’s sarcoma-associated herpesvirus was originally detected in Kaposi’s sarcoma biopsy specimens. Since its discovery, it has been possible to detect virus in cell lines established from AIDS-associated body cavity-based B-cell lymphoma and to propagate virus from primary Kaposi’s sarcoma lesions in a human renal embryonic cell line, 293. In this study, we analyzed the infectivity of Kaposi’s sarcoma-associated herpesvirus produced from these two sources. Viral isolates from cultured cutaneous primary KS cells was transmitted to an Epstein-Barr virus-negative Burkitt’s B-lymphoma cell line, Louckes, and compared to virus induced from a body cavity-based B-cell lymphoma cell line. While propagation of body cavity-based B-cell lymphoma-derived virus was not observed in 293 cell cultures, infection with viral isolates obtained from primary Kaposi’s sarcoma lesions induced injury in 293 cells typical of herpesvirus infection and was associated with apoptotic cell death. Interestingly, transient overexpression of the Kaposi’s sarcoma-associated herpesvirus v-Bcl-2 homolog delayed the process of apoptosis and prolonged the survival of infected 293 cells. In contrast, the broad-spectrum caspase inhibitors Z-VAD-fmk and Z-DEVD-fmk failed to protect infected cell cultures, suggesting that Kaposi’s sarcoma-associated herpesvirus-induced apoptosis occurs through a Bcl-2-dependent pathway. Kaposi’s sarcoma-associated herpesvirus isolates from primary Kaposi’s sarcoma lesions and body cavity-based lymphomas therefore may differ and are likely to have distinct contributions to the pathophysiology of Kaposi’s sarcoma.
A Novel YY1-Independent Silencer Represses the Activity of the Human Papillomavirus Type 16 Enhancer
Authors: O’Connor Mark J. , Stünkel Walter , Zimmermann Holger , Koh Choon-Heng , Bernard Hans-Ulrich 
Published: December 2019

ABSTRACT
Regulation of the human papillomavirus type 16 (HPV-16) E6 promoter is a complex process in which transcriptional repression as well as activation plays an important role. Here, we identify a negative regulatory element that in the context of a continuous long control region fragment overcomes the activation of the HPV-16 enhancer. This silencing element, which we have termed a PSM (papillomavirus silencing motif), consists of two copies of the sequence 5′-TAYAATAAT-3′ that overlap the origin of replication. Each copy of this 9-bp sequence binds the same unknown cellular factor, which we refer to as PSM-BP (PSM binding protein). Both copies of the binding sequence are required for transcriptional repression, and we provide evidence that suggests that this particular organization results in the stabilization of a PSM-BP dimer. The silencing motif, while functioning in either orientation, showed a positional requirement between the enhancer and the promoter. Experiments with both a heterologous enhancer and a promoter also demonstrated a general ability of this element to function as a transcriptional silencer in non-HPV systems. Our findings provide an important addition to our understanding of HPV-16 gene regulation and an interesting model for the study of transcriptional repression.
The Origin DNA-Binding and Single-Stranded DNA-Binding Domains of Simian Virus 40 Large T Antigen Are Distinct
Authors: Wu Chunxiao , Edgil Dianna , Simmons Daniel T. 
Published: December 2019

ABSTRACT
Little is known about the ability of simian virus 40 (SV40) T antigen to bind single-stranded DNA. We demonstrate here that a mutant (259-708) missing the first 258 amino acids of T antigen and its origin-binding domain bound single-stranded DNA at close to normal levels, whereas a mutant containing only the first 259 amino acids failed to bind any single-stranded DNA. The 259-708 mutant also assembled into high-molecular-weight oligomers in the presence of single-stranded DNA. Its ATPase activity was stimulated by single-stranded DNA similarly to the wild type (WT). Furthermore, WT T antigen’s ability to bind to single-stranded DNA was inhibited by the binding of two monoclonal antibodies that recognize a region after residue 362. These results show that the domain responsible for binding to single-stranded DNA is completely separate from the origin-binding domain.
Morbillivirus Downregulation of CD46
Authors: Galbraith Sareen E. , Tiwari Ashok , Baron Michael D. , Lund Brett T. , Barrett Thomas , Cosby S. Louise 
Published: December 2019

ABSTRACTThere is evidence that CD46 (membrane cofactor protein) is a cellular receptor for vaccine and laboratory-passaged strains of measles virus (MV). Following infection with these MV strains, CD46 is downregulated from the cell surface, and consequent complement-mediated lysis has been shown to occur upon infection of a human monocytic cell line. The MV hemagglutinin (H) protein alone is capable of inducing this downregulation. Some wild-type strains of MV fail to downregulate CD46, despite infection being prevented by anti-CD46 antibodies. In this study we show that CD46 is also downregulated to the same extent by wild-type, vaccine, and laboratory-passaged strains of rinderpest virus (RPV), although CD46 did not appear to be the receptor for RPV. Expression of the RPV H protein by a nonreplicating adenovirus vector was also found to cause this downregulation. A vaccine strain of peste des petits ruminants virus caused slight downregulation of CD46 in infected Vero cells, while wild-type and vaccine strains of canine distemper virus and a wild-type strain of dolphin morbillivirus failed to downregulate CD46. Downregulation of CD46 can, therefore, be a function independent of the use of this protein as a virus receptor.
Simian T-Cell Lymphotropic Virus Type 1 from
Mandrillus sphinx
as a Simian Counterpart of Human T-Cell Lymphotropic Virus Type 1 Subtype D
Authors: Mahieux Renaud , Chappey Colombe , Georges-Courbot Marie-Claude , Dubreuil Guy , Mauclere Philippe , Georges Alain , Gessain Antoine 
Published: December 2019

ABSTRACT

A recent serological and molecular survey of a semifree-ranging colony of mandrills (
Mandrillus sphinx
) living in Gabon, central Africa, indicated that 6 of 102 animals, all males, were infected with simian T-cell lymphotropic virus type 1 (STLV-1). These animals naturally live in the same forest area as do human inhabitants (mostly Pygmies) who are infected by the recently described human T-cell lymphotropic virus type 1 (HTLV-1) subtype D. We therefore investigated whether these mandrills were infected with an STLV-1 related to HTLV-1 subtype D. Nucleotide and/or amino acid sequence analyses of complete or partial long terminal repeat (LTR),
env
, and
rex
regions showed that HTLV-1 subtype D-specific mutations were found in three of four STLV-1-infected mandrills, while the remaining monkey was infected by a different STLV-1 subtype. Phylogenetic studies conducted on the LTR as well as on the
env
gp21 region showed that these three new STLV-1 strains from mandrills fall in the same monophyletic clade, supported by high bootstrap values, as do the sequences of HTLV-1 subtype D. These data show, for the first time, the presence of the same subtype of primate T-cell lymphotropic virus type 1 in humans and wild-caught monkeys originating from the same geographical area. This strongly supports the hypothesis that mandrills are the natural reservoir of HTLV-1 subtype D, although the possibility that another monkey species living in the same area could be the original reservoir of both human and mandrill viruses cannot be excluded. Due to the quasi-identity of both human and monkey viruses, interspecies transmission episodes leading to such a clade may have occurred recently.
Simian Sarcoma-Associated Virus Fails To Infect Chinese Hamster Cells despite the Presence of Functional Gibbon Ape Leukemia Virus Receptors
Authors: Ting Yuan-Tsang , Wilson Carolyn A. , Farrell Karen B. , Chaudry G. Jilani , Eiden Maribeth V. 
Published: December 2019

ABSTRACT
We have sequenced the envelope genes from each of the five members of the gibbon ape leukemia virus (GALV) family of type C retroviruses. Four of the GALVs, including GALV strain SEATO (GALV-S), were originally isolated from gibbon apes, whereas the fifth member of this family, simian sarcoma-associated virus (SSAV), was isolated from a woolly monkey and shares 78% amino acid identity with GALV-S. To determine whether these viruses have identical host ranges, we evaluated the susceptibility of several cell lines to either GALV-S or SSAV infection. GALV-S and SSAV have the same host range with the exception of Chinese hamster lung E36 cells, which are susceptible to GALV-S but not SSAV. We used retroviral vectors that differ only in their envelope composition (e.g., they contain either SSAV or GALV-S envelope protein) to show that the envelope of SSAV restricts entry into E36 cells. Although unable to infect E36 cells, SSAV infects GALV-resistant murine cells expressing the E36-derived viral receptor, HaPit2. These results suggest that the receptors present on E36 cells function for SSAV. We have constructed several vectors containing GALV-S/SSAV chimeric envelope proteins to map the region of the SSAV envelope that blocks infection of E36 cells. Vectors bearing chimeric envelopes comprised of the N-terminal region of the GALV-S SU protein and the C-terminal region of SSAV infect E36 cells, whereas vectors containing the N-terminal portion of the SSAV SU protein and C-terminal portion of GALV-S fail to infect E36 cells. This finding indicates that the region of the SSAV envelope protein responsible for restricting SSAV infection of E36 cells lies within its amino-terminal region.
p53 Status Does Not Determine Outcome of E1B 55-Kilodalton Mutant Adenovirus Lytic Infection
Authors: Goodrum Felicia D. , Ornelles David A. 
Published: December 2019

ABSTRACT

The ability of the adenovirus type 5 E1B 55-kDa mutants
dl
1520 and
dl
338 to replicate efficiently and independently of the cell cycle, to synthesis viral DNA, and to lyse infected cells did not correlate with the status of p53 in seven cell lines examined. Rather, cell cycle-independent replication and virus-induced cell killing correlated with permissivity to viral replication. This correlation extended to S-phase HeLa cells, which were more susceptible to virus-induced cell killing by the E1B 55-kDa mutant virus than HeLa cells infected during G
1
. Wild-type p53 had only a modest effect on E1B mutant virus yields in H1299 cells expressing a temperature-sensitive p53 allele. The defect in E1B 55-kDa mutant virus replication resulting from reduced temperature was as much as 10-fold greater than the defect due to p53 function. At 39°C, the E1B 55-kDa mutant viruses produced wild-type yields of virus and replicated independently of the cell cycle. In addition, the E1B 55-kDa mutant viruses directed the synthesis of late viral proteins to levels equivalent to the wild-type virus level at 39°C. We have previously shown that the defect in mutant virus replication can also be overcome by infecting HeLa cells during S phase. Taken together, these results indicate that the capacity of the E1B 55-kDa mutant virus to replicate independently of the cell cycle does not correlate with the status of p53 but is determined by yet unidentified mechanisms. The cold-sensitive nature of the defect of the E1B 55-kDa mutant virus in both late gene expression and cell cycle-independent replication leads us to speculate that these functions of the E1B 55-kDa protein may be linked.
Recombinant, Replication-Defective Adenovirus Gene Transfer Vectors Induce Cell Cycle Dysregulation and Inappropriate Expression of Cyclin Proteins
Authors: Wersto Robert P. , Rosenthal Eugene R. , Seth Prem K. , Eissa N. Tony , Donahue Robert E. 
Published: December 2019

ABSTRACT

First-generation adenovirus (Ad) vectors that had been rendered replication defective by removal of the E1 region of the viral genome (ΔE1) or lacking the Ad E3 region in addition to E1 sequences (ΔE1ΔE3) induced G
2
cell cycle arrest and inhibited traverse across G
1
/S in primary and immortalized human bronchial epithelial cells. Cell cycle arrest was independent of the cDNA contained in the expression cassette and was associated with the inappropriate expression and increase in cyclin A, cyclin B1, cyclin D, and cyclin-dependent kinase p34

cdc2

protein levels. In some instances, infection with ΔE1 or ΔE1ΔE3 Ad vectors produced aneuploid DNA histogram patterns and induced polyploidization as a result of successive rounds of cell division without mitosis. Cell cycle arrest was absent in cells infected with a second-generation ΔE1Ad vector in which all of the early region E4 except the sixth open reading frame was also deleted. Consequently, E4 viral gene products present in ΔE1 or ΔE1ΔE3 Ad vectors induce G
2
growth arrest, which may pose new and unintended consequences for human gene transfer and gene therapy.
Interaction of Theiler’s Virus with Intermediate Filaments of Infected Cells
Authors: Nédellec Patrick , Vicart Patrick , Laurent-Winter Christine , Martinat Cécile , Prévost Marie-Christine , Brahic Michel 
Published: December 2019

ABSTRACT
Theiler’s murine encephalomyelitis virus is a neurotropic murine picornavirus which replicates permissively and causes a cytopathic effect in the BHK-21 cell line. We examined the interactions between the GDVII and DA strains of Theiler’s virus and BHK-21 host cell proteins in a virus overlay assay. We observed binding of the virions to two proteins of approximately 60 kDa. These proteins were microsequenced and identified as desmin and vimentin, two main components of the intermediate filament network. The association between desmin or vimentin and virions was demonstrated by immunoprecipitation. Anti-desmin and anti-vimentin monoclonal antibodies precipitated GDVII or DA virions from extracts of infected BHK-21 cells. The intracellular distributions of virions and of the desmin and vimentin intermediate filaments of BHK-21 cells were investigated by two-color immunofluorescence confocal microscopy. Following infection, the intermediate filament network was rearranged into a shell-like structure which surrounded a viral inclusion. Finally, close contact between GDVII virus particles and 10-nm intermediate filaments was observed by electron microscopy.
Effect of Bafilomycin A1 and Nocodazole on Endocytic Transport in HeLa Cells: Implications for Viral Uncoating and Infection
Authors: Bayer Nora , Schober Daniela , Prchla Elisabeth , Murphy Robert F. , Blaas Dieter , Fuchs Renate 
Published: December 2019

ABSTRACT

Bafilomycin A1 (baf), a specific inhibitor of vacuolar proton ATPases, is commonly employed to demonstrate the requirement of low endosomal pH for viral uncoating. However, in certain cell types baf also affects the transport of endocytosed material from early to late endocytic compartments. To characterize the endocytic route in HeLa cells that are frequently used to study early events in viral infection, we used
35
S-labeled human rhinovirus serotype 2 (HRV2) together with various fluid-phase markers. These virions are taken up via receptor-mediated endocytosis and undergo a conformational change to C-antigenic particles at a pH of <5.6, resulting in release of the genomic RNA and ultimately in infection (E. Prchla, E. Kuechler, D. Blaas, and R. Fuchs, J. Virol. 68:3713–3723, 1994). As revealed by fluorescence microscopy and subcellular fractionation of microsomes by free-flow electrophoresis (FFE), baf arrests the transport of all markers in early endosomes. In contrast, the microtubule-disrupting agent nocodazole was found to inhibit transport by accumulating marker in endosomal carrier vesicles (ECV), a compartment intermediate between early and late endosomes. Accordingly, lysosomal degradation of HRV2 was suppressed, whereas its conformational change and infectivity remained unaffected by this drug. Analysis of the subcellular distribution of HRV2 and fluid-phase markers in the presence of nocodazole by FFE revealed no difference from the control incubation in the absence of nocodazole. ECV and late endosomes thus have identical electrophoretic mobilities, and intraluminal pHs of <5.6 and allow uncoating of HRV2. As bafilomycin not only dissipates the low endosomal pH but also blocks transport from early to late endosomes in HeLa cells, its inhibitory effect on viral infection could in part also be attributed to trapping of virus in early endosomes which might lack components essential for uncoating. Consequently, inhibition of viral uncoating by bafilomycin cannot be taken to indicate a low pH requirement only.
Human Immunodeficiency Virus Induces a Dual Regulation of Bcl-2, Resulting in Persistent Infection of CD4+T- or Monocytic Cell Lines
Authors: Aillet Fabienne , Masutani Hiroshi , Elbim Carole , Raoul Hervé , Chêne Laurent , Nugeyre Marie-Thérèse , Paya Carlos , Barré-Sinoussi Françoise , Gougerot-Pocidalo Marie-Anne , Israël Nicole 
Published: December 2019

ABSTRACTThis work aims at characterizing the interplay between human immunodeficiency virus type 1 (HIV-1) and the antiapoptotic cellular protein Bcl-2 responsible for a persistent infection in lymphoblastoid T (J.Jhan) or monocytic (U937) cells. We report that the kinetics of Bcl-2 protein level during the establishment of a chronic infection is biphasic, characterized by a transient decrease followed by restoration to the initial level. The extent and duration of this transient decrease were inversely correlated with the basal level of Bcl-2 as shown by kinetics of Bcl-2 levels in J.Jhan or U937 clones exhibiting different levels of Bcl-2. Using these clones, we also showed that Bcl-2 downregulates HIV-1 replication. Therefore, the cells overexpressing Bcl-2 are characterized by a low viral burden which, in turn, has little effect on the level of this protein. The observed bipasic kinetics is the result of a dual regulation of Bcl-2 induced by HIV-1 infection itself: an upregulation at the transcriptional level of thebcl-2gene concomitant with a downregulation at the protein level. Convergent data suggest that this downregulation is caused by the oxidative stress induced by the infection itself as shown by the associated modulations of glutathione and thioredoxin levels and by the prevention of these dysregulations byN-acetylcysteine. Altogether, these data indicate that infection first results in a decrease of Bcl-2, permitting an initial boost of replication. Then, as the synthesis at the transcriptional level proceeds, the replication is negatively controlled by Bcl-2 to reach a balance characterized by low virus production and a level of Bcl-2 compatible with cell survival. We suggest that the basal level of Bcl-2, together with infection-inducible transcription factors able to activatebcl-2gene transcription, is a critical cellular determinant in the tendency toward an acute or a persistent infection.
Ectopic Expression of Hepatitis C Virus Core Protein Differentially Regulates Nuclear Transcription Factors
Authors: Shrivastava Anju , Manna Sunil K. , Ray Ranjit , Aggarwal Bharat B. 
Published: December 2019

ABSTRACTThe putative core protein of hepatitis C virus (HCV) regulates cellular growth and a number of cellular promoters. To further understand its effect, we investigated the role of the core protein in the endogenous regulation of two distinct transcription factors, nuclear factor-κB (NF-κB) and activating protein-1 (AP-1), and the related mitogen-activated protein kinase kinase (MAPKK) and c-Jun N-terminal kinase (JNK). Stable cell transfectants expressing the HCV core protein suppressed tumor necrosis factor (TNF)-induced NF-κB activation. Supershift analysis revealed that NF-κB consists of p50 and p65 subunits. This correlated with inhibition of the degradation of IκBα, the inhibitory subunit of NF-κB. The effect was not specific to TNF, as suppression in core protein-expressing cells was also observed in response to a number of other inflammatory agents known to activate NF-κB. In contrast to the effect on NF-κB, the HCV core protein constitutively activated AP-1, which correlated with the activation of JNK and MAPKK, which are known to regulate AP-1. These observations indicated that the core protein targets transcription factors known to be involved in the regulation of inflammatory responses and the immune system.
Study of Dengue Virus Infection in SCID Mice Engrafted with Human K562 Cells
Authors: Lin Yi-Ling , Liao Ching-Len , Chen Li-Kuang , Yeh Chia-Tsui , Liu Chiu-I , Ma Shiou-Hwa , Huang Yu-Ying , Huang Yue-Ling , Kao Chuan-Liang , King Chwan-Chuen 
Published: December 2019

ABSTRACTHere we report that severe combined immunodeficient (SCID) mice engrafted with human K562 cells (K562-SCID mice) can be used as an animal model to study dengue virus (DEN) infection. After intratumor injection into K562 cell masses of PL046, a Taiwanese DEN-2 human isolate, the K562-SCID mice showed neurological signs of paralysis and died at approximately 2 weeks postinfection. In addition to being detected in the tumor masses, high virus titers were detected in the peripheral blood and the brain tissues, indicating that DEN had replicated in the infected K562-SCID mice. In contrast, the SCID mice were resistant to DEN infection and the mock-infected K562-SCID mice survived for over 3 months. These data illustrate that DEN infection contributed directly to the deaths of the infected K562-SCID mice. Other serotypes of DEN were also used to infect the K562-SCID mice, and the mortality rates of the infected mice varied with different challenge strains, suggesting the existence of diverse degrees of virulence among DENs. To determine whether a neutralizing antibody against DEN in vitro was also protective in vivo, the K562-SCID mice were challenged with DEN-2 and received antibody administration at the same time or 1 day earlier. Our results revealed that the antibody-treated mice exhibited a reduction in mortality and a delay of paralysis onset after DEN infection. In contrast to K562-SCID, the persistently DEN-infected K562 cells generated in vitro invariably failed to be implanted in the mice. It seems that in the early stage of implantation, a gamma interferon activated, nitric oxide-mediated anti-DEN effect might play a role in the innate immunity against DEN-infected cells. The system described herein offers an opportunity to explore DEN replication in vivo and to test various antiviral protocols in infected hosts.
Self-Inactivating Lentivirus Vector for Safe and Efficient In Vivo Gene Delivery
Authors: Zufferey Romain , Dull Thomas , Mandel Ronald J. , Bukovsky Anatoly , Quiroz Dulce , Naldini Luigi , Trono Didier 
Published: December 2019

ABSTRACT
In vivo transduction of nondividing cells by human immunodeficiency virus type 1 (HIV-1)-based vectors results in transgene expression that is stable over several months. However, the use of HIV-1 vectors raises concerns about their safety. Here we describe a self-inactivating HIV-1 vector with a 400-nucleotide deletion in the 3′ long terminal repeat (LTR). The deletion, which includes the TATA box, abolished the LTR promoter activity but did not affect vector titers or transgene expression in vitro. The self-inactivating vector transduced neurons in vivo as efficiently as a vector with full-length LTRs. The inactivation design achieved in this work improves significantly the biosafety of HIV-derived vectors, as it reduces the likelihood that replication-competent retroviruses will originate in the vector producer and target cells, and hampers recombination with wild-type HIV in an infected host. Moreover, it improves the potential performance of the vector by removing LTR sequences previously associated with transcriptional interference and suppression in vivo and by allowing the construction of more-stringent tissue-specific or regulatable vectors.