bluuebunny/crossref_metadata_2025_split huggingface dataset:
Model for the Interaction of Gammaherpesvirus 68 RING-CH Finger Protein mK3 with Major Histocompatibility Complex Class I and the Peptide-Loading Complex
Authors: Wang Xiaoli , Lybarger Lonnie , Connors Rose , Harris Michael R. , Hansen Ted H. 
Published: July 2004

ABSTRACTThe mK3 protein of gammaherpesvirus 68 and the kK5 protein of Kaposi's sarcoma-associated herpesvirus are members of a family of structurally related viral immune evasion molecules that all possess a RING-CH domain with ubiquitin ligase activity. These proteins modulate the expression of major histocompatibility complex class I molecules (mK3 and kK5) as well as other molecules like ICAM-1 and B7.2 (kK5). Previously, mK3 was shown to ubiquitinate nascent class I molecules, resulting in their rapid degradation, and this process was found to be dependent on TAP and tapasin, endoplasmic reticulum molecules involved in class I assembly. Here, we demonstrate that in murine cells, kK5 does not affect class I expression but does downregulate human B7.2 molecules in a TAP/tapasin-independent manner. These differences in substrate specificity and TAP/tapasin dependence between mK3 and kK5 permitted us, using chimeric molecules, to map the sites of mK3 interaction with TAP/tapasin and to determine the requirements for substrate recognition by mK3. Our findings indicate that mK3 interacts with TAP1 and -2 via their C-terminal domains and with class I molecules via their N-terminal domains. Furthermore, by orienting the RING-CH domain of mK3 appropriately with respect to class I, mK3 binding to TAP/tapasin, rather than the presence of unique sequences in class I, appears to be the primary determinant of substrate specificity.
Human Cytomegalovirus-Encoded Interleukin-10 Homolog Inhibits Maturation of Dendritic Cells and Alters Their Functionality
Authors: Chang W. L. William , Baumgarth Nicole , Yu Dong , Barry Peter A. 
Published: July 2004

ABSTRACTInterleukin-10 (IL-10) suppresses the maturation and cytokine production of dendritic cells (DCs), key regulators of adaptive immunity, and prevents the activation and polarization of naïve T cells towards protective gamma interferon-producing effectors. We hypothesized that human cytomegalovirus (HCMV) utilizes its viral IL-10 homolog (cmvIL-10) to attenuate DC functionality, thereby subverting the efficient induction of antiviral immune responses. RNA and protein analyses demonstrated that the cmvIL-10 gene was expressed with late gene kinetics. Treatment of immature DCs (iDCs) with supernatant from HCMV-infected cultures inhibited both the lipopolysaccharide-induced DC maturation and proinflammatory cytokine production. These inhibitory effects were specifically mediated through the IL-10 receptor and were not observed when DCs were treated with supernatant of cells infected with a cmvIL-10-knockout mutant. Incubation of iDCs with recombinant cmvIL-10 recapitulated the inhibition of maturation. Furthermore, cmvIL-10 had pronounced long-term effects on those DCs that could overcome this inhibition of maturation. It enhanced the migration of mature DCs (mDCs) towards the lymph node homing chemokine but greatly reduced their cytokine production. The inability of mDCs to secrete IL-12 was maintained, even when they were restimulated by the activated T-cell signal CD40 ligand in the absence of cmvIL-10. Importantly, cmvIL-10 potentiates these anti-inflammatory effects, at least partially, by inducing endogenous cellular IL-10 expression in DCs. Collectively, we show that cmvIL-10 causes long-term functional alterations at all stages of DC activation.
Chimeras of Duck and Heron Hepatitis B Viruses Provide Evidence for Functional Interactions between Viral Components of Pregenomic RNA Encapsidation
Authors: Ostrow Kristin M. , Loeb Daniel D. 
Published: July 2004

ABSTRACT

Packaging of hepadnavirus pregenomic RNA (pgRNA) into capsids, or encapsidation, requires several viral components. The viral polymerase (P) and the capsid subunit (C) are necessary for pgRNA encapsidation. Previous studies of duck hepatitis B virus (DHBV) indicated that two
cis-
acting sequences on pgRNA are required for encapsidation: ε, which is near the 5′ end of pgRNA, and region II, located near the middle of pgRNA. Later studies suggested that the intervening sequence between these two elements may also make a contribution. It has been demonstrated for DHBV that ε interacts with P to facilitate encapsidation, but it is not known how other
cis-
acting sequences contribute to encapsidation. We analyzed chimeras of DHBV and a related virus, heron hepatitis B virus (HHBV), to gain insight into the interactions between the various viral components during pgRNA encapsidation. We learned that having ε and P derived from the same virus was not sufficient for high levels of encapsidation, implying that other viral interactions contribute to encapsidation. Chimeric analysis showed that a large sequence containing region II may interact with P and/or C for efficient encapsidation. Further analysis demonstrated that possibly an RNA-RNA interaction between the intervening sequence and region II facilitates pgRNA encapsidation. Together, these results identify functional interactions among various viral components that contribute to pgRNA encapsidation.
A Short Peptide at the Amino Terminus of the Sendai Virus C Protein Acts as an Independent Element That Induces STAT1 Instability
Authors: Garcin Dominique , Marq Jean-Baptiste , Iseni Fréderic , Martin Stephen , Kolakofsky Daniel 
Published: July 2004

ABSTRACT

The Sendai virus C protein acts to dismantle the interferon-induced cellular antiviral state in an MG132-sensitive manner, in part by inducing STAT1 instability. This activity of C maps to the first 23 amino acids (C
1-23
) of the 204-amino-acid (aa)-long protein (C
1-204
). C
1-23
was found to act as an independent viral element that induces STAT1 instability, since this peptide fused to green fluorescent protein (C
1-23
/GFP) is at least as active as C
1-204
in this respect. This peptide also induces the degradation of C
1-23
/GFP and other proteins to which it is fused. Most of C
1-204
, and particularly its amino-terminal half, is predicted to be structurally disordered. C
1-23
as a peptide was found to be disordered by circular dichroism, and the first 11 aa have a strong potential to form an amphipathic α-helix in low concentrations of trifluoroethanol, which is thought to mimic protein-protein interaction. The critical degradation-determining sequence of C
1-23
was mapped by mutation to eight residues near its N terminus:
4
FLKKILKL
11
. All the large hydrophobic residues of
4
FLKKILKL
11
, plus its ability to form an amphipathic α-helix, were found to be critical for STAT1 degradation. In contrast, C
1-23
/GFP self-degradation did not require
8
ILKL
11
, nor the ability to form an α-helix throughout this region. Remarkably, C
1-23
/GFP also stimulated C
1-204
degradation, and this degradation in
trans
required the same peptide determinants as for STAT1. Our results suggest that C
1-204
coordinates its dual activities of regulating viral RNA synthesis and counteracting the host innate antiviral response by sensing both its own intracellular concentration and that of STAT1.
Human Respiratory Coronavirus OC43: Genetic Stability and Neuroinvasion
Authors: St-Jean Julien R. , Jacomy Hélène , Desforges Marc , Vabret Astrid , Freymuth François , Talbot Pierre J. 
Published: July 2004

ABSTRACT
The complete genome sequences of the human coronavirus OC43 (HCoV-OC43) laboratory strain from the American Type Culture Collection (ATCC), and a HCoV-OC43 clinical isolate, designated Paris, were obtained. Both genomes are 30,713 nucleotides long, excluding the poly(A) tail, and only differ by 6 nucleotides. These six mutations are scattered throughout the genome and give rise to only two amino acid substitutions: one in the spike protein gene (I958F) and the other in the nucleocapsid protein gene (V81A). Furthermore, the two variants were shown to reach the central nervous system (CNS) after intranasal inoculation in BALB/c mice, demonstrating neuroinvasive properties. Even though the ATCC strain could penetrate the CNS more effectively than the Paris 2001 isolate, these results suggest that intrinsic neuroinvasive properties already existed for the HCoV-OC43 ATCC human respiratory isolate from the 1960s before it was propagated in newborn mouse brains. It also demonstrates that the molecular structure of HCoV-OC43 is very stable in the environment (the two variants were isolated ca. 40 years apart) despite virus shedding and chances of persistence in the host. The genomes of the two HCoV-OC43 variants display 71, 53.1, and 51.2% identity with those of mouse hepatitis virus A59, severe acute respiratory syndrome human coronavirus Tor2 strain (SARS-HCoV Tor2), and human coronavirus 229E (HCoV-229E), respectively. HCoV-OC43 also possesses well-conserved motifs with regard to the genome sequence of the SARS-HCoV Tor2, especially in open reading frame 1b. These results suggest that HCoV-OC43 and SARS-HCoV may share several important functional properties and that HCoV-OC43 may be used as a model to study the biology of SARS-HCoV without the need for level three biological facilities.
Hepatitis C Virus Infection Activates the Immunologic (Type II) Isoform of Nitric Oxide Synthase and Thereby Enhances DNA Damage and Mutations of Cellular Genes
Authors: Machida Keigo , Cheng Kevin T.-H. , Sung Vicky M.-H. , Lee Ki Jeong , Levine Alexandra M. , Lai Michael M. C. 
Published: July 2004

ABSTRACTHepatitis C virus (HCV) infection causes hepatitis, hepatocellular carcinoma, and B-cell lymphomas in a significant number of patients. Previously we have shown that HCV infection causes double-stranded DNA breaks and enhances the mutation frequency of cellular genes, including proto-oncogenes and immunoglobulin genes. To determine the mechanisms, we studied in vitro HCV infection of cell culture. Here we report that HCV infection activated the immunologic (type II) isoform of nitric oxide (NO) synthase (NOS), i.e., inducible NOS (iNOS), thereby inducing NO, which in turn induced DNA breaks and enhanced the mutation frequencies of cellular genes. Treatment of HCV-infected cells with NOS inhibitors or small interfering RNA specific for iNOS abolished most of these effects. Expression of the core protein or nonstructural protein 3 (NS3), but not the other viral proteins, in B cells or hepatocytes induced iNOS and DNA breaks, which could be blocked by NOS inhibitors. The core protein also enhanced the mutation frequency of cellular genes in hepatocytes derived from HCV core transgenic mice compared with that in control mice. The iNOS promoter was activated more than fivefold in HCV-infected cells, as revealed by a luciferase reporter assay driven by the iNOS promoter. Similarly, the core and NS3 proteins also induced the same effects. Therefore, we conclude that HCV infection can stimulate the production of NO through activation of the gene for iNOS by the viral core and NS3 proteins. NO causes DNA breaks and enhances DNA mutation. This sequence of events provides a mechanism for HCV pathogenesis and oncogenesis.
Beyond Help: Direct Effector Functions of Human Immunodeficiency Virus Type 1-Specific CD4+T Cells
Authors: Norris Philip J. , Moffett Howell F. , Yang Otto O. , Kaufmann Daniel E. , Clark Margaret J. , Addo Marylyn M. , Rosenberg Eric S. 
Published: July 2004

ABSTRACTThe immune correlates of protection in human immunodeficiency virus type 1 (HIV-1) infection remain poorly defined, particularly the contribution of CD4+T cells. Here we explore the effector functions of HIV-1-specific CD4+T cells. We demonstrate HIV-1 p24-specific CD4+-T-cell cytolytic activity in peripheral blood mononuclear cells directly ex vivo and after enrichment by antigen-specific stimulation. We further show that in a rare long-term nonprogressor, both an HIV-1-specific CD4+-T-cell clone and CD4+T cells directly ex vivo exert potent suppression of HIV-1 replication. Suppression of viral replication was dependent on cell-cell contact between the effector CD4+T cells and the target cells. While the antiviral effector activity of CD8+T cells has been well documented, these results strongly suggest that HIV-1-specific CD4+T cells are capable of directly contributing to antiviral immunity.
Porcine Endogenous Retroviruses Infect Cells Lacking Cognate Receptors by an Alternative Pathway: Implications for Retrovirus Evolution and Xenotransplantation
Authors: Lavillette Dimitri , Kabat David 
Published: July 2004

ABSTRACT
A PHQ motif near the amino termini of gammaretroviral envelope glycoprotein surface (SU) subunits is important for infectivity but not for incorporation into virions or binding to cognate receptors. The H residue of this motif is most critical, with all substitutions we tested being inactive. Interestingly, porcine endogenous retroviruses (PERVs) of all three host-range groups, A, B, and C, lack full PHQ motifs, but most members have an H residue at position 10. H10A PERV mutants are noninfectious but were efficiently transactivated by adding to the assays a PHQ-containing SU or receptor-binding subdomain (RBD) derived from a gibbon ape leukemia virus (GALV). A requirement of this transactivation was a functional GALV receptor on the cells. In contrast to this heterologous transactivation, PERV RBDs and SUs were inactive in all tested cells, including porcine ST-IOWA cells. Surprisingly, transactivation by GALV RBD enabled wild-type or H10A mutant PERVs of all three host-range groups to efficiently infect cells from humans and rodents that lack functional PERV receptors and it substantially enhanced infectivities of wild-type PERVs, even for cells with PERV receptors. Thus, PERVs can suboptimally infect cells that contain cognate receptors or they can employ a transactivation pathway to more efficiently infect all cells. This ability to infect cells lacking cognate receptors was previously demonstrated only for nontransmissible variant gammaretroviruses with recombinant and mutant envelope glycoproteins. We conclude that some endogenously inherited mammalian retroviruses also have a receptor-independent means for overcoming host-range and interference barriers, implying a need for caution in xenotransplantation, especially of porcine tissues.
Vaccinia Virus Morphogenesis: A13 Phosphoprotein Is Required for Assembly of Mature Virions
Authors: Unger Bethany , Traktman Paula 
Published: July 2004

ABSTRACT

The 70-amino-acid A13L protein is a component of the vaccinia virus membrane. We demonstrate here that the protein is expressed at late times of infection, undergoes phosphorylation at a serine residue(s), and becomes encapsidated in a monomeric form. Phosphorylation is dependent on Ser40, which lies within the proline-rich motif SPPP. Because phosphorylation of the A13 protein is only minimally affected by disruption of the viral F10 kinase or H1 phosphatase, a cellular kinase is likely to be involved. We generated an inducible recombinant in which A13 protein expression is dependent upon the inclusion of tetracycline in the culture medium. Repression of the A13L protein spares the biochemical progression of the viral life cycle but arrests virion morphogenesis. Virion assembly progresses through the formation of immature virions (IVs); however, these virions do not acquire nucleoids, and DNA crystalloids accumulate in the cytoplasm. Further development into intracellular mature virions is blocked, causing a 1,000-fold decrease in the infectious virus yield relative to that obtained in the presence of the inducer. We also determined that the temperature-sensitive phenotype of the viral mutant C
ts
40 is due to a nucleotide transition within the A13L gene that causes a Thr
48
→Ile substitution. This substitution disrupts the function of the A13 protein but does not cause thermolability of the protein; at the nonpermissive temperature, virion morphogenesis arrests at the stage of IV formation. The A13L protein, therefore, is part of a newly recognized group of membrane proteins that are dispensable for the early biogenesis of the virion membrane but are essential for virion maturation.
Characterization of the Mouse Adeno-Associated Virus
AAVS1
Ortholog
Authors: Dutheil Nathalie , Yoon-Robarts Miran , Ward Peter , Henckaerts Els , Skrabanek Lucy , Berns Kenneth I. , Campagne Fabien , Linden R. Michael 
Published: July 2004

ABSTRACT

The nonpathogenic human adeno-associated virus (AAV) has developed a mechanism to integrate its genome into human chromosome 19 at 19q13.4 (termed
AAVS1
), thereby establishing latency. Here, we provide evidence that the chromosomal signals required for site-specific integration are conserved in the mouse genome proximal to the recently identified
Mbs85
gene. These sequence motifs can be specifically nicked by the viral Rep protein required for the initiation of site-specific AAV DNA integration. Furthermore, these signals can serve as a minimal origin for Rep-dependent DNA replication. In addition, we isolated the mouse Mbs85 proximal promoter and show transcriptional activity in three mouse cell lines.
Ngari Virus Is a Bunyamwera Virus Reassortant That Can Be Associated with Large Outbreaks of Hemorrhagic Fever in Africa
Authors: Gerrard Sonja R. , Li Li , Barrett Alan D. , Nichol Stuart T. 
Published: July 2004

ABSTRACT

Two isolates of a virus of the genus
Orthobunyavirus
(family
Bunyaviridae
) were obtained from hemorrhagic fever cases during a large disease outbreak in East Africa in 1997 and 1998. Sequence analysis of regions of the three genomic RNA segments of the virus (provisionally referred to as Garissa virus) suggested that it was a genetic reassortant virus with S and L segments derived from Bunyamwera virus but an M segment from an unidentified virus of the genus
Orthobunyavirus
. While high genetic diversity (52%) was revealed by analysis of virus M segment nucleotide sequences obtained from 21 members of the genus
Orthobunyavirus
, the Garissa and Ngari virus M segments were almost identical. Surprisingly, the Ngari virus L and S segments showed high sequence identity with those of Bunyamwera virus, showing that Garissa virus is an isolate of Ngari virus, which in turn is a Bunyamwera virus reassortant. Ngari virus should be considered when investigating hemorrhagic fever outbreaks throughout sub-Saharan Africa.
The relation between bone marrow angiogenesis and the proliferation index Ki-67 in multiple myeloma
Authors: Alexandrakis M G , Passam F H , Dambaki C , Pappa C A , Stathopoulos E N 
Published: July 2004

Aim:Angiogenesis correlates with disease progression in various haematological malignancies. This study investigated the association between microvascular density (MVD) and the Ki-67 proliferation index (Ki-67 PI), bone marrow infiltration, and C reactive protein (CRP) in patients with multiple myeloma.Methods:Bone marrow MVD was examined in 44 biopsies at diagnosis and 15 in plateau phase by immunostaining the endothelial cells with a monoclonal antibody to CD34. The Ki-67 PI was evaluated by a double immunostaining technique using the monoclonal antibodies MIB-1 and CD38.Results:MVD, Ki-67 PI, bone marrow infiltration, and CRP were significantly higher in pretreatment patients than in controls and decreased in patients achieving plateau phase. MVD significantly correlated with Ki-67 PI and infiltration, and Ki-67 correlated with infiltration.Conclusion:In multiple myeloma, apart from being a marker of proliferative activity, Ki-67 is also associated with bone marrow angiogenesis and tumour burden.
Intraepithelial lymphocytes in the villous tip: do they indicate potential coeliac disease?
Authors: Biagi F , Luinetti O , Campanella J , Klersy C , Zambelli C , Villanacci V , Lanzini A , Corazza G R 
Published: July 2004

Background:The counting of intraepithelial lymphocytes (IELs) in the villous tips of architecturally normal small bowel biopsy specimens was proposed as a method to measure mucosal infiltration in gluten sensitive patients.Aims:To apply this straightforward method in duodenal biopsy specimens from patients affected by potential coeliac disease (PCD) to verify whether it can discriminate these patients from controls.Methods:Paraffin wax embedded duodenal sections from 11 patients affected by PCD were stained with an antihuman CD3 antibody. Sections from 19 patients affected by treated coeliac disease (TCD) and 17 patients in whom coeliac disease was excluded were stained with the same antibody to serve as controls. The slides were examined blindly. IELs/20 enterocytes in five randomly chosen villous tips were counted. Patients affected by PCD were all on a gluten containing diet. They had an architecturally normal duodenal mucosa and were positive for endomysial antibody. Both TCD and non-coeliac controls were negative for endomysial antibody.Results:The mean villous tip IEL scores were 4.6 (SD, 1.5; range, 1.4–7.8) in non-coeliac controls, 7.9 (SD, 4.0; range, 2.0–18.6) in TCD, and 9.2 (SD, 4.7; range, 5.8–21.8) in patients with PCD. The difference between PCD and non-coeliac controls was significant.Conclusions:This is a very simple and sufficiently reliable method to count IELs. In patients with an architecturally normal duodenal mucosa, the IEL count in villous tips helps to distinguish between patients with PCD and non-coeliac controls.
Proliferative activity in postmenopausal endometrium: the lurking potential for giving rise to an endometrial adenocarcinoma
Authors: Sivridis E , Giatromanolaki A 
Published: July 2004

Aims:To investigate proliferation in disease free postmenopausal endometrium and that harbouring endometrial adenocarcinoma—is there a dynamic, yet lurking, potential for atrophic endometrium to give rise to endometrial adenocarcinoma?Material/methods:The study comprised 84 disease free endometria from asymptomatic postmenopausal women who had undergone hysterectomy for prolapse, and 50 endometrioid cell type endometrial adenocarcinomas with adjacent uninvolved postmenopausal endometrium. The non-neoplastic tissues were separated histologically into active, inactive, and mixed forms, although only the first two categories were studied immunohistochemically for oestrogen and progesterone receptors (ERs, PRs), epidermal growth factor receptor (EGFR), Ki-67, and angiogenic activity.Results:All postmenopausal endometria were atrophic, but only 42 were inactive; of the remaining samples, 22 were weakly proliferative and 20 were mixed active and inactive. In contrast, the non-neoplastic component of 43 of the 50 endometrial adenocarcinomas examined was of the active form; four specimens were of the pure and 39 of the mixed form. Interestingly, high ER and PR expression was seen in active and inactive endometria, but only the former were EGFR positive and had high proliferative (Ki-67) and angiogenic activity. A similar trend was also shown by the non-neoplastic atrophic endometrium adjacent to endometrial adenocarcinoma.Conclusions:At least half of the disease free postmenopausal atrophic endometria show a weak proliferative pattern, either diffuse or focal, probably as a response to continuous low level oestrogenic stimulation. These tissues have a latent, although very small, carcinogenic potential, as demonstrated by the immunohistochemical profile and their frequent association with adjacent endometrial adenocarcinoma.