bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simian Immunodeficiency Virus (SIV) Envelope-Specific Fabs with High-Level Homologous Neutralizing Activity: Recovery from a Long-Term-Nonprogressor SIV-Infected Macaque
Authors: Glamann Joakim , Burton Dennis R. , Parren Paul W. H. I. , Ditzel Henrik J. , Kent Karen A. , Arnold Caroline , Montefiori David , Hirsch Vanessa M. 
Published: December 2019

ABSTRACT
An antibody phage display library was constructed from RNA extracted from lymph node cells of a simian immunodeficiency virus (SIV)-infected long-term-nonprogressor macaque. Seven gp120-reactive Fabs were obtained by selection of the library against SIV monomeric gp120. Although each of the Fabs was unique in sequence, there were two distinct groups based on epitope recognition, neutralizing activity in vitro, and molecular analysis. Group 1 Fabs did not neutralize SIV and bound to a linear epitope in the V3 loop of the SIV envelope. In contrast, two of the group 2 Fabs neutralized homologous, neutralization-sensitive SIVsm isolates with high efficiency but failed to neutralize heterologous SIVmac isolates. Based on competition enzyme-linked immunosorbent assays with mouse monoclonal antibodies of known specificity, these Fabs reacted with a conformational epitope that includes domains V3 and V4 of the SIV envelope. These neutralizing and nonneutralizing Fabs provide valuable standardized and renewable reagents for studying the role of antibody in preventing or modifying SIV infection in vivo.
Characterization of
cis
-Acting and NS1 Protein-Responsive Elements in the p6 Promoter of Parvovirus B19
Authors: Gareus Ralph , Gigler Andreas , Hemauer Andrea , Leruez-Ville Marianne , Morinet Frédéric , Wolf Hans , Modrow Susanne 
Published: December 2019

ABSTRACT

Parvovirus B19 infections are associated with diverse clinical manifestations, ranging from no symptoms to severe symptoms. The virus shows an extreme tropism for replication in erythroid progenitor cells, possibly due to the activity of the only functional promoter (p6) of the B19 virus genome in combination with both cell- and cell cycle-specific factors and the
trans
-activator protein NS1. As presented here, p6 promoter sequences derived from several B19 virus isolates proved to be highly conserved. Furthermore, mutations did not affect any of the potential binding sites for transcription factors. One variation of the base at position 223 was identified only in B19 virus isolates derived from patients with persistent infection or chronic arthritis. To determine promoter activity and to characterize regulatory elements, sequences spanning the total p6 promoter and subfragments of them were introduced into a eukaryotic expression vector upstream of the luciferase gene (from
Photinus pyralis
). After transfection into HeLa, CEM, BJAB, and K562 cells, the p6 promoter was found to be highly active. When introduced into the erythroid cell line K562, p6-controlled transcription exceeded that of the simian virus 40 promoter-enhancer used as a control by more than 25-fold. Sequence elements relevant for promoter activity mapped to the regions from nucleotides (nt) 100 to 190 and 233 to 298. Also, the segment from nt 343 to 400 downstream of the TATA box was important for transcriptional activity in HeLa and K562 cells. By transfecting the promoter-luciferase constructs into a HeLa cell line stably carrying the viral NS1 gene under the control of an inducible promoter, transcriptional activity mediated by the p6 promoter rose significantly after induction of NS1 expression. The region from nt 100 to 160 proved to be essential for NS1-mediated transcriptional activation. Furthermore, NS1-mediated transactivation was dependent on the presence of two GC-rich elements arranged in tandem upstream of the TATA box. These data indicate that NS1-mediated p6 transactivation is dependent on a multicomponent complex combining NS1 with ATF, NF-κB/c-Rel, and GC-box binding cellular factors.
Distinct Mechanisms Trigger Apoptosis in Human Immunodeficiency Virus Type 1-Infected and in Uninfected Bystander T Lymphocytes
Authors: Herbein Georges , Van Lint Carine , Lovett Jennie L. , Verdin Eric 
Published: December 2019

ABSTRACTApoptosis is a main feature of AIDS pathogenesis and is thought to play a role in the progressive decrease of CD4+T lymphocytes in infected individuals. To determine whether apoptosis occurs in infected and/or in uninfected peripheral blood T lymphocytes, we have used a recombinant human immunodeficiency virus type 1 (HIV-1) infectious clone expressing the green fluorescent protein (GFP). Using flow cytometry, we have determined the incidence of apoptosis by either terminal transferase dUTP nick end labeling or annexin-V assays in different cell subpopulations, i.e., in CD4+or CD8+T cells that were GFP positive or negative. After HIV-1 infection of purified peripheral blood lymphocytes, we observed that apoptosis occurred mostly in infected CD4+peripheral blood lymphocytes. Remarkably, the presence of monocyte-derived macrophages in the culture increased dramatically the apoptosis of uninfected bystander T lymphocytes, while apoptosis in HIV-infected T lymphocytes was not changed. We therefore demonstrate that HIV-induced apoptosis results from at least two distinct mechanisms: (i) direct apoptosis in HIV-infected CD4+T lymphocytes and (ii) indirect apoptosis in uninfected T cells mediated by antigen-presenting cells.
Transient Viral DNA Replication and Repression of Viral Transcription Are Supported by the C-Terminal Domain of the Bovine Papillomavirus Type 1 E1 Protein
Authors: Ferran Maureen C. , McBride Alison A. 
Published: December 2019

ABSTRACT
The bovine papillomavirus type 1 E1 protein is important for viral DNA replication and transcriptional repression. It has been proposed that the full-length E1 protein consists of a small N-terminal and a larger C-terminal domain. In this study, it is shown that an E1 polypeptide containing residues 132 to 605 (which represents the C-terminal domain) is able to support transient viral DNA replication, although at a level lower than that supported by the wild-type protein. This domain can also repress E2-mediated transactivation from the P89 promoter as well as the wild-type E1 protein can.
Protective Efficacy of DNA Vaccines against Duck Hepatitis B Virus Infection
Authors: Triyatni M. , Jilbert A. R. , Qiao M. , Miller D. S. , Burrell C. J. 
Published: December 2019

ABSTRACT
The efficacy of DNA vaccines encoding the duck hepatitis B virus (DHBV) pre-S/S and S proteins were tested in Pekin ducks. Plasmid pcDNA I/Amp DNA containing the DHBV pre-S/S or S genes was injected intramuscularly three times, at 3-week intervals. All pre-S/S and S-vaccinated ducks developed total anti-DHBs and specific anti-S antibodies with similar titers reaching 1/10,000 to 1/50,000 and 1/2,500 to 1/4,000, respectively, after the third vaccination. However, following virus challenge, significant differences in the rate of virus removal from the bloodstream and the presence of virus replication in the liver were found between the groups. In three of four S-vaccinated ducks, 90% of the inoculum was removed between <5 and 15 min postchallenge (p.c.) and no virus replication was detected in the liver at 4 days p.c. In contrast, in all four pre-S/S-vaccinated ducks, 90% of the inoculum was removed between 60 and 90 min p.c. and DHBsAg was detected in 10 to 40% of hepatocytes. Anti-S serum abolished virus infectivity when preincubated with DHBV before inoculation into 1-day-old ducklings and primary duck hepatocyte cultures, while anti-pre-S/S serum showed very limited capacity to neutralize virus infectivity in these two systems. Thus, although both DNA vaccines induced high titers of anti-DHBs antibodies, anti-S antibodies induced by the S-DNA construct were highly effective in neutralizing virus infectivity while similar levels of anti-S induced by the pre-S/S-DNA construct conferred only very limited protection. This phenomenon requires further clarification, particularly in light of the development of newer HBV vaccines containing pre-S proteins and a possible discrepancy between anti-HBs titers and protective efficacy.
Endogenous Production of β-Chemokines by CD4+, but Not CD8+, T-Cell Clones Correlates with the Clinical State of Human Immunodeficiency Virus Type 1 (HIV-1)-Infected Individuals and May Be Responsible for Blocking Infection with NonSyncytium-Inducing HIV-1 In Vitro
Authors: Saha Kunal , Bentsman Galina , Chess Leonard , Volsky David J. 
Published: December 2019

ABSTRACTRecent studies have demonstrated that the β-chemokines RANTES, MIP-1α, and MIP-1β suppress human immunodeficiency virus type 1 (HIV-1) replication in vitro and may play an important role in protecting exposed but uninfected individuals from HIV-1 infection. However, levels of β-chemokines in AIDS patients are comparable to and can exceed levels in nonprogressing individuals, indicating that global β-chemokine production may have little effect on HIV-1 disease progression. We sought to clarify the role of β-chemokines in nonprogressors and AIDS patients by examination of β-chemokine production and HIV-1 infection in patient T-lymphocyte clones established by herpesvirus saimiri immortalization. Both CD4+and CD8+clones were established, and they resembled primary T cells in their phenotypes and expression of activated T-cell markers. CD4+T-cell clones from all patients had normal levels of mRNA-encoding CCR5, a coreceptor for non-syncytium-inducing (NSI) HIV-1. CD4+clones from nonprogressors and CD8+clones from AIDS patients secreted high levels of RANTES, MIP1α, and MIP-1β. In contrast, CD4+clones from AIDS patients produced no RANTES and little or no MIP-1α or MIP-1β. The infection of CD4+clones with the NSI HIV-1 strain ADA revealed an inverse correlation to β-chemokine production; clones from nonprogressors were poorly susceptible to ADA replication, but clones from AIDS patients were highly infectable. The resistance to ADA infection in CD4+clones from nonprogressors could be partially reversed by treatment with anti-β-chemokine antibodies. These results indicate that CD4+cells can be protected against NSI-HIV-1 infection in culture through endogenously produced factors, including β-chemokines, and that β-chemokine production by CD4+, but not CD8+, T cells may constitute one mechanism of disease-free survival for HIV-1-infected individuals.
Clearance of an Influenza A Virus by CD4+T Cells Is Inefficient in the Absence of B Cells
Authors: Topham David J. , Doherty Peter C. 
Published: December 2019

ABSTRACTThe primary CD8+T-cell response protected most B-cell-deficient μMT mice against intranasal infection with the HKx31 influenza A virus. Prior exposure did not prevent reinfection upon homologous challenge, and the recall CD8+T-cell response cleared the virus from the lung within 7 days. Depleting the CD8+T cells substantially reduced the capacity of these primed mice to deal with the infection, in spite of evidence for established CD4+T-cell memory. Thus, the control of this relatively mild influenza virus by both primary and secondary CD4+T-cell responses is relatively inefficient in the absence of B cells and CD8+T cells.
Recombinant Measles Viruses with Mutations in the C, V, or F Gene Have Altered Growth Phenotypes In Vivo
Authors: Valsamakis Alexandra , Schneider Henriette , Auwaerter Paul G. , Kaneshima Hideto , Billeter Martin A. , Griffin Diane E. 
Published: December 2019

ABSTRACT
An understanding of the determinants of measles virus (MV) virulence has been hampered by the lack of an experimental model of infection. We have previously demonstrated that virulence phenotypes in human infections are faithfully reproduced by infection of human thymus/liver (thy/liv) implants engrafted into SCID mice, where the virus grows primarily in stromal cells but induces thymocyte apoptosis (P. G. Auwaerter et al., J. Virol. 70:3734–3740, 1996). To begin to elucidate the roles of the C protein, V protein, and the 5′ untranslated region of the F gene (F 5′UTR) in MV infection in vivo, the replication of strains bearing mutations of these genes was compared to that of the parent sequence-tagged Edmonston strain (EdTag). Growth curves show that mutants fall into two phenotypic classes. One class of mutants demonstrated kinetics of growth similar to that of EdTag, with decreased peak titers. The second class of mutants manifested peak titers similar to that of EdTag but had different replication kinetics. Abrogation of V expression led to delayed and markedly prolonged replication. Additionally, thymocyte survival was prolonged and implant architecture was preserved throughout the course of infection. In contrast, massive bystander thymocyte death occurred after infection with EdTag and all other mutants. A mutant which overexpressed V in Vero cells (V+) had the opposite phenotype of the A mutant not expressing V (V−). V+ grew more rapidly than EdTag with 100-fold-greater levels of virus production 3 days after infection. These results suggest that C, V, and the F 5′UTR are accessory factors required for efficient virus replication in vivo. In addition, thymocyte survival after V− infection suggests this protein may play multiple roles in pathogenesis of MV infection of thymus. Since these recombinant mutant viruses grew identically to the parent virus in Vero cells, the data show that thy/liv implants are an excellent model for investigating the determinants of MV virulence.
Tyrosine 112 of Latent Membrane Protein 2A Is Essential for Protein Tyrosine Kinase Loading and Regulation of Epstein-Barr Virus Latency
Authors: Fruehling Sara , Swart Rachel , Dolwick KristIne M. , Kremmer Elisabeth , Longnecker Richard 
Published: December 2019

ABSTRACTLatent membrane protein 2A (LMP2A) of Epstein-Barr virus (EBV) is expressed on the plasma membrane of B lymphocytes latently infected with EBV and blocks B-cell receptor (BCR) signal transduction in EBV-immortalized B cells in vitro. The LMP2A amino-terminal domain that is essential for the LMP2A-mediated block on BCR signal transduction contains eight tyrosine residues. Association of Syk protein tyrosine kinase (PTK) with LMP2A occurs at the two tyrosines of the LMP2A immunoreceptor tyrosine-based activation motif, and it is hypothesized that Lyn PTK associates with the YEEA amino acid motif at LMP2A tyrosine 112 (Y112). To examine the specific association of Lyn PTK to LMP2A, a panel of LMP2A cDNA expression vectors containing LMP2A mutations were transfected into an EBV-negative B-cell line and analyzed for Lyn and LMP2A coimmunoprecipitation. Lyn associates with wild-type LMP2A and other LMP2A mutant constructs, but Lyn association is lost in the LMP2A construct containing a tyrosine (Y)-to-phenylalanine (F) mutation at LMP2A residue Y112 (LMP2AY112F). Next, the LMP2AY112F mutation was recombined into the EBV genome to generate stable lymphoblastoid cell lines (LCLs) transformed with the LMP2AY112F mutant virus. Analysis of BCR-mediated signal transduction in the LMP2AY112F LCLs revealed loss of the LMP2A-mediated block in BCR signal transduction. In addition, LMP2A was not tyrosine phosphorylated in LMP2AY112F LCLs. Together these data indicate the importance of the LMP2A Y112 residue in the ability of LMP2A to block BCR-mediated signal transduction and place the role of this residue and its interaction with Lyn PTK as essential to LMP2A phosphorylation, PTK loading, and down-modulation of PTKs involved in BCR-mediated signal transduction.
Phylogenetic Analysis of the Entire Genome of Influenza A (H3N2) Viruses from Japan: Evidence for Genetic Reassortment of the Six Internal Genes
Authors: Lindstrom Stephen E. , Hiromoto Yasuaki , Nerome Reiko , Omoe Katsuhiko , Sugita Shigeo , Yamazaki Yoshinao , Takahashi Tomoko , Nerome Kuniaki 
Published: December 2019

ABSTRACT
Nucleotide sequences of all eight RNA segments of 10 human H3N2 influenza viruses isolated during a 5-year period from 1993 to 1997 were determined and analyzed phylogenetically in order to define the evolutionary pathways of all genes in a parallel fashion. It was evident that the hemagglutinin and neuraminidase genes of these viruses evolved essentially in a single lineage and that amino acid changes accumulated sequentially with respect to time. In contrast, amino acid differences in the internal proteins were erratic and did not accumulate over time. Parallel analysis of the phylogenetic patterns of all genes revealed that the evolutionary pathways of the six internal genes were not linked to the surface glycoproteins. Genes coding for the basic polymerase-1, nucleoprotein, and matrix proteins of 1997 isolates were closest phylogenetically to those of earlier isolates of 1993 and 1994. Furthermore, all six internal genes of four viruses isolated in the 1995 epidemic season consistently divided into two distinct branch clusters, and two 1995 isolates contained PB2 genes apparently originating from those of viruses before 1993. It was apparent that the lack of correlation between the topologies of the phylogenetic trees of the genes coding for the surface glycoproteins and internal proteins was a reflection of genetic reassortment among human H3N2 viruses. This is the first evidence demonstrating the occurrence of genetic reassortment involving the internal genes of human H3N2 viruses. Furthermore, internal protein variability coincided with marked increases in the activity of H3N2 viruses in 1995 and 1997.
Persistent Infection of Epstein-Barr Virus-Positive B Lymphocytes by Human Herpesvirus 8
Authors: Kliche Stefanie , Kremmer Elisabeth , Hammerschmidt Wolfgang , Koszinowski Ulrich , Haas Jürgen 
Published: December 2019

ABSTRACT

In patients with Kaposi’s sarcoma (KS), human herpesvirus 8 (HHV-8) can invariably be detected in KS tumor tissue and, at a lower frequency, in prostate tissue and peripheral blood B lymphocytes. Whereas the majority of KS spindle cells are latently infected by HHV-8, linear HHV-8 genomes characteristic for lytic infection are found predominantly in the peripheral blood cells of KS patients. In this study, we show that HHV-8 can stably infect B lymphocytes in vitro in the presence of Epstein-Barr virus (EBV). We were able to generate immortalized HHV-8
+
/EBV
+
lymphoblastoid cell lines (LCLs) derived from peripheral blood mononuclear cells (PBMC) of EBV
−
and EBV
+
donors. In HHV-8
+
/EBV
+
LCLs, which have the phenotype of activated B lymphocytes (CD19
+
, surface immunoglobulin M, CD23
+
, CD30
+
, CD80
+
), HHV-8 was still present after more than 25 passages (more than 9 months of culture). Latent viral transcripts and proteins were present in nonstimulated HHV-8
+
/EBV
+
LCLs. After induction by phorbol ester and
n
-butyrate, HHV-8
+
/EBV
+
LCLs expressed lytic HHV-8 transcripts and proteins. Moreover, HHV-8 could be serially passaged from HHV-8
+
/EBV
+
LCLs to fresh PBMC.
Development of a Self-Inactivating Lentivirus Vector
Authors: Miyoshi Hiroyuki , Blömer Ulrike , Takahashi Masayo , Gage Fred H. , Verma Inder M. 
Published: December 2019

ABSTRACT
We have constructed a new series of lentivirus vectors based on human immunodeficiency virus type 1 (HIV-1) that can transduce nondividing cells. The U3 region of the 5′ long terminal repeat (LTR) in vector constructs was replaced with the cytomegalovirus (CMV) promoter, resulting in Tat-independent transcription but still maintaining high levels of expression. A self-inactivating (SIN) vector was constructed by deleting 133 bp in the U3 region of the 3′ LTR, including the TATA box and binding sites for transcription factors Sp1 and NF-κB. The deletion is transferred to the 5′ LTR after reverse transcription and integration in infected cells, resulting in the transcriptional inactivation of the LTR in the proviruses. SIN viruses can be generated with no significant decreases in titer. Injection of viruses into the rat brain showed that a SIN vector containing the green fluorescent protein gene under the control of the internal CMV promoter transduced neurons as efficiently as a wild-type vector. Interestingly, a wild-type vector without an internal promoter also successfully transduced neurons in the brain, indicating that the HIV-1 LTR promoter is transcriptionally active in neurons even in the absence of Tat. Furthermore, injection of viruses into the subretinal space of the rat eye showed that wild-type vector transduced predominantly retinal pigment epithelium and photoreceptor cells, while SIN vector was able to transduce other types of retinal cells, including bipolar, Müller, horizontal, and amacrine cells. This finding suggests that the HIV-1 LTR can negatively influence the internal CMV promoter in some cell types. SIN HIV vectors should be safer for gene therapy, and they also have broader applicability as a means of high-level gene transfer and expression in nondividing cells.
A Fifteen-Amino-Acid Peptide Inhibits Human Papillomavirus E1-E2 Interaction and Human Papillomavirus DNA Replication In Vitro
Authors: Kasukawa Hiroaki , Howley Peter M. , Benson John D. 
Published: December 2019

ABSTRACT
Mutation of the conserved glutamic acid residue at position 39 of human papillomavirus type 16 (HPV-16) E2 to alanine (E39A) disrupts its E1 interaction activity and its replication function in transient replication assays but does not affect E2 transcriptional activation. This E39A mutation also disrupts replication activity of HPV-16 E2 in HPV-16 in vitro DNA replication. On this basis, we designed 23- and 15-amino-acid peptides derived from HPV-16 E2 sequences flanking the E39 residue and tested the ability of these peptides to inhibit interaction between HPV-16 E1 and E2 in vitro. The inhibitory activity of these peptides was specific, since analogous peptides in which alanine was substituted for the E39 residue did not inhibit interaction. The 15-amino-acid peptide E2N-WP15 was the smallest peptide tested that effectively inhibited HPV-16 E1-E2 interaction. This peptide also inhibited in vitro replication of HPV-16 DNA. The efficacy of E2N-WP15 was not exclusive to HPV-16: this peptide also inhibited interaction of HPV-11 E1 with the E2 proteins of both HPV-11 and HPV-16 and inhibited in vitro replication with these same combinations of E1 and E2 proteins. These results provide further evidence that E1-E2 interaction is required for papillomavirus DNA replication and constitute the first demonstration that inhibition of this interaction is sufficient to prevent HPV DNA replication in vitro.