bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simian Immunodeficiency Virus Replicates to High Levels in Naturally Infected African Green Monkeys without Inducing Immunologic or Neurologic Disease
Authors: Broussard Suzanne R. , Staprans Silvija I. , White Robert , Whitehead Evelyn M. , Feinberg Mark B. , Allan Jonathan S. 
Published: July 2002

ABSTRACTAfrican green monkeys can maintain long-term persistent infection with simian immunodeficiency viruses (SIVagm) without developing AIDS and thus provide an important model for understanding mechanisms of natural host resistance to disease. This study assessed the levels and anatomic distribution of SIVagm in healthy, naturally infected monkeys. Quantitative competitive reverse transcriptase PCR assays developed to measure SIVagm from two African green monkey subspecies demonstrated high levels of SIV RNA in plasma (>6 × 106RNA copies/ml) in sabaeus and vervet monkeys. Infectious virus was readily recovered from plasma and peripheral blood mononuclear cells and shown to be highly cytopathic in human cell lines and macrophages. SIVagm DNA levels were highest in the gastrointestinal tract, suggesting that the gut is a major site for SIVagm replication in vivo. Appreciable levels of virus were also found within the brain parenchyma and the cerebrospinal fluid (CSF), with lower levels detected in peripheral blood cells and lymph nodes. Virus isolates from the CSF and brain parenchyma readily infected macrophages in culture, whereas lymph node isolates were more restricted to growth in human T-cell lines. Comparison ofenvV2-C4 sequences showed extensive amino acid diversity between SIVagm recovered from the central nervous system and that recovered from lymphoid tissues. Homology between brain and CSF viruses, macrophage tropism, and active replication suggest compartmentalization in the central nervous system without associated neuropathology in naturally infected monkeys. These studies provide evidence that the nonpathogenic nature of SIVagm in the natural host can be attributed neither to more effective host control over viral replication nor to differences in the tissue and cell tropism from those for human immunodeficiency virus type 1-infected humans or SIV-infected macaques.
Murine Coronavirus Spike Protein Determines the Ability of the Virus To Replicate in the Liver and Cause Hepatitis
Authors: Navas Sonia , Seo Su-Hun , Chua Ming Ming , Sarma Jayasri Das , Lavi Ehud , Hingley Susan T. , Weiss Susan R. 
Published: July 2002

ABSTRACT

Recombinant mouse hepatitis viruses (MHV) differing only in the spike gene, containing A59, MHV-4, and MHV-2 spike genes in the background of the A59 genome, were compared for their ability to replicate in the liver and induce hepatitis in weanling C57BL/6 mice infected with 500 PFU of each virus by intrahepatic injection. Penn98-1, expressing the MHV-2 spike gene, replicated to high titer in the liver, similar to MHV-2, and induced severe hepatitis with extensive hepatocellular necrosis. S
A59
R13, expressing the A59 spike gene, replicated to a somewhat lower titer and induced moderate to severe hepatitis with zonal necrosis, similar to MHV-A59. S
4
R21, expressing the MHV-4 spike gene, replicated to a minimal extent and induced few if any pathological changes, similar to MHV-4. Thus, the extent of replication and the degree of hepatitis in the liver induced by these recombinant viruses were determined largely by the spike protein.
Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen 1 Mediates Episome Persistence through
cis
-Acting Terminal Repeat (TR) Sequence and Specifically Binds TR DNA
Authors: Ballestas Mary E. , Kaye Kenneth M. 
Published: July 2002

ABSTRACT

Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) (also known as human herpesvirus 8) latently infects KS tumors, primary effusion lymphomas (PELs), and PEL cell lines. In latently infected cells, KSHV DNA is maintained as circularized, extrachromosomal episomes. To persist in proliferating cells, KSHV episomes must replicate and efficiently segregate to progeny nuclei. In uninfected B-lymphoblastoid cells, KSHV latency-associated nuclear antigen (LANA1) is necessary and sufficient for persistence of artificial episomes containing specific KSHV DNA. In previous work, the
cis
-acting sequence required for episome persistence contained KSHV terminal-repeat (TR) DNA and unique KSHV sequence. We now show that
cis
-acting KSHV TR DNA is necessary and sufficient for LANA1-mediated episome persistence. Furthermore, LANA1 binds TR DNA in mobility shift assays and a 20-nucleotide LANA1 binding sequence has been identified. Since LANA1 colocalizes with KSHV episomes along metaphase chromosomes, these results are consistent with a model in which LANA1 may bridge TR DNA to chromosomes during mitosis to efficiently segregate KSHV episomes to progeny nuclei.
Branched Polyamines Cure Prion-Infected Neuroblastoma Cells
Authors: Supattapone Surachai , Wille Holger , Uyechi Lisa , Safar Jiri , Tremblay Patrick , Szoka Francis C. , Cohen Fred E. , Prusiner Stanley B. , Scott Michael R. 
Published: July 2002

ABSTRACT

Branched polyamines, including polyamidoamine and polypropyleneimine (PPI) dendrimers, are able to purge PrP
Sc
, the disease-causing isoform of the prion protein, from scrapie-infected neuroblastoma (ScN2a) cells in culture (S. Supattapone, H.-O. B. Nguyen, F. E. Cohen, S. B. Prusiner, and M. R. Scott, Proc. Natl. Acad. Sci. USA 96:14529–14534, 1999). We now demonstrate that exposure of ScN2a cells to 3 μg of PPI generation 4.0/ml for 4 weeks not only reduced PrP
Sc
to a level undetectable by Western blot but also eradicated prion infectivity as determined by a bioassay in mice. Exposure of purified RML prions to branched polyamines in vitro disaggregated the prion rods, reduced the β-sheet content of PrP 27-30, and rendered PrP 27-30 susceptible to proteolysis. The susceptibility of PrP
Sc
to proteolytic digestion induced by branched polyamines in vitro was strain dependent. Notably, PrP
Sc
from bovine spongiform encephalopathy-infected brain was susceptible to PPI-mediated denaturation in vitro, whereas PrP
Sc
from natural sheep scrapie-infected brain was resistant. Fluorescein-labeled PPI accumulated specifically in lysosomes, suggesting that branched polyamines act within this acidic compartment to mediate PrP
Sc
clearance. Branched polyamines are the first class of compounds shown to cure prion infection in living cells and may prove useful as therapeutic, disinfecting, and strain-typing reagents for prion diseases.
Definitive Assignment of Proton Selectivity and Attoampere Unitary Current to the M2 Ion Channel Protein of Influenza A Virus
Authors: Lin Tse-I , Schroeder Cornelia 
Published: July 2002

ABSTRACT

The viral ion channel protein M2 supports the transit of influenza virus and its glycoproteins through acidic compartments of the cell. M2 conducts endosomal protons into the virion to initiate uncoating and, by equilibrating the pH at
trans
-Golgi membranes, preserves the native conformation of acid-sensitive viral hemagglutinin. The exceptionally low conductance of the M2 channel thwarted resolution of single channels by electrophysiological techniques. Assays of liposome-reconstituted M2 yielded the average unitary channel current of the M2 tetramer—1.2 aA (1.2 × 10
−18
A) at neutral pH and 2.7 to 4.1 aA at pH 5.7—which activates the channel. Extrapolation to physiological temperature predicts 4.8 and 40 aA, respectively, and a unitary conductance of 0.03 versus 0.4 fS. This minute activity, below previous estimates, appears sufficient for virus reproduction, but low enough to avert abortive cytotoxicity. The unitary permeability of M2 was within the range reported for other proton channels. To address the ion selectivity of M2, we exploited the coupling of ionic influx and efflux in sealed liposomes. Metal ion fluxes were monitored by proton counterflow, employing a pH probe 1,000 times more sensitive than available Na
+
or K
+
probes. Even low-pH-activated M2 did not conduct Na
+
and K
+
. The proton selectivity of M2 was estimated to be at least 3 × 10
6
(over sodium or potassium ions), in agreement with electrophysiological studies. The stringent proton selectivity of M2 suggests that the cytopathology of influenza virus does not involve direct perturbation of cellular sodium or potassium gradients.
The Late Domain of Human Immunodeficiency Virus Type 1 p6 Promotes Virus Release in a Cell Type-Dependent Manner
Authors: Demirov Dimiter G. , Orenstein Jan M. , Freed Eric O. 
Published: July 2002

ABSTRACT

The p6 domain of human immunodeficiency virus type 1 (HIV-1) is located at the C terminus of the Gag precursor protein Pr55
Gag
. Previous studies indicated that p6 plays a critical role in HIV-1 particle budding from virus-expressing HeLa cells. In this study, we performed a detailed mutational analysis of the N terminus of p6 to map the sequences required for efficient virus release. We observed that the highly conserved P-T/S-A-P motif located near the N terminus of p6 is remarkably sensitive to change; even conservative mutations in this sequence imposed profound virus release defects in HeLa cells. In contrast, single and double amino acid substitutions outside the P-T/S-A-P motif had no significant effect on particle release. The introduction of stop codons one or two residues beyond the P-T/S-A-P motif markedly impaired virion release, whereas truncation four residues beyond P-T/S-A-P had no effect on particle production in HeLa cells. By examining the effects of p6 mutation in biological and biochemical analyses and by electron microscopy, we defined the role of p6 in particle release and virus replication in a panel of T-cell and adherent cell lines and in primary lymphocytes and monocyte-derived macrophages. We demonstrated that the effects of p6 mutation on virus replication are markedly cell type dependent. Intriguingly, even in T-cell lines and primary lymphocytes in which p6 mutations block virus replication, these changes had little or no effect on particle release. However, p6-mutant particles produced in T-cell lines and primary lymphocytes exhibited a defect in virion-virion detachment, resulting in the production of tethered chains of virions. Virus release in monocyte-derived macrophages was markedly inhibited by p6 mutation. To examine further the cell type-specific virus release defect in HeLa versus T cells, transient heterokaryons were produced between HeLa cells and the Jurkat T-cell line. These heterokaryons display a T-cell-like phenotype with respect to the requirement for p6 in particle release. The results described here define the role of p6 in virus replication in a wide range of cell types and reveal a strong cell type-dependent requirement for p6 in virus particle budding.
Activation of Cytomegalovirus in Pig-to-Primate Organ Xenotransplantation
Authors: Mueller Nicolas J. , Barth Rolf N. , Yamamoto Shin , Kitamura Hiroshi , Patience Clive , Yamada Kazuhiko , Cooper David K. C. , Sachs David H. , Kaur Amitinder , Fishman Jay A. 
Published: July 2002

ABSTRACTXenotransplantation of porcine organs carries the risk of reactivation of latent virus in donor and recipient tissues as well as transmission of viruses between species. We have investigated the activation of baboon cytomegalovirus (BCMV) and porcine CMV (PCMV) in a pig-to-primate model of xenotransplantation. Tissues originating from a series of six swine-to-baboon composite thymokidney xenotransplants were investigated. Four immunosuppressed baboons died (survival range, 7 to 27 days) with the graft in situ. Increases in BCMV DNA copy numbers occurred in three (75%) of these baboons and was thought to be responsible for pneumonitis and the death of one animal. In two baboons, disseminated intravascular coagulation was successfully treated by graftectomy and discontinuation of immunosuppression. PCMV was upregulated in five of six xenografts (83%). PCMV infection was associated with ureteric necrosis in one xenograft. Although significantly increased in native tissues, low levels of BCMV and PCMV were also detected in tissues other than that of the native viral host species. The cross-species presence of CMV did not appear to cause clinical or histological signs of invasive disease. Thus, viral infections with clinical disease were restricted to tissues of the native species of each virus. Intensive immune suppression currently required for xenotransplantation results in a significant risk of reactivation of latent infections by BCMV and PCMV. It is not yet known whether viral DNA detected across species lines represents cellular microchimerism, ongoing viral infection, or uptake of free virus. The observation of graft injury by PCMV demonstrates that CMV will be an important pathogen in immunosuppressed xenograft recipients. Strategies must be developed to exclude CMV from porcine organ donors.
Comparison of Two Aquatic Alphaviruses, Salmon Pancreas Disease Virus and Sleeping Disease Virus, by Using Genome Sequence Analysis, Monoclonal Reactivity, and Cross-Infection
Authors: Weston Jonathan , Villoing Stéphane , Brémont Michel , Castric Jeanette , Pfeffer Martin , Jewhurst Victoria , McLoughlin Marian , Rødseth OddMagne , Christie Karen Elina , Koumans Joseph , Todd Daniel 
Published: July 2002

ABSTRACT

Cell culture isolates of salmon pancreas disease virus (SPDV) of farmed Atlantic salmon and sleeping disease virus (SDV) of rainbow trout were compared. Excluding the poly(A) tracts, the genomic nucleotide sequences of SPDV and SDV RNAs include 11,919 and 11,900 nucleotides, respectively. Phylogenetic analysis places SPDV and SDV between the New World viruses of Venezuelan equine encephalitis virus and Eastern equine encephalitis virus and the Old World viruses of Aura virus and Sindbis virus. When compared to each other, SPDV and SDV show 91.1% nucleotide sequence identity over their complete genomes, with 95 and 93.6% amino acid identities over their nonstructural and structural proteins, respectively. Notable differences between the two viruses include a 24-nucleotide insertion in the C terminus of nsP3 protein of SPDV and amino acid sequence variation at the C termini of the capsid and E1 proteins. Experimental infections of Atlantic salmon and rainbow trout with SPDV and SDV confirmed that the disease lesions induced by SPDV and SDV were similar in nature. Although infections with SPDV and SDV produced similar levels of histopathology in rainbow trout, SDV induced significantly less severe lesions in salmon than did SPDV. Virus neutralization tests performed with sera from experimentally infected salmon indicated that SPDV and SDV belonged to the same serotype; however, antigenic variation was detected among SDV and geographically different SPDV isolates by using monoclonal antibodies. Although SPDV and SDV exhibit minor biological differences, we conclude on the basis of the close genetic similarity that SPDV and SDV are closely related isolates of the same virus species for which the name
Salmonid alphavirus
is proposed.
Structural Requirements for the Assembly of Norwalk Virus-Like Particles
Authors: Bertolotti-Ciarlet Andrea , White Laura J. , Chen Rong , Prasad B. V. Venkataram , Estes Mary K. 
Published: July 2002

ABSTRACT
Norwalk virus (NV) is the prototype strain of a group of human caliciviruses responsible for epidemic outbreaks of acute gastroenteritis. While these viruses do not grow in tissue culture cells or animal models, expression of the capsid protein in insect cells results in the self-assembly of recombinant NV virus-like particles (rNV VLPs) that are morphologically and antigenically similar to native NV. The X-ray structure of the rNV VLPs has revealed that the capsid protein folds into two principal domains: a shell (S) domain and a protruding (P) domain (B. V. V. Prasad, M. E. Hardy, T. Dokland, J. Bella, M. G. Rossmann, and M. K. Estes, Science 286:287-290, 1999). To investigate the structural requirements for the assembly of rNV VLPs, we performed mutational analyses of the capsid protein. We examined the ability of 10 deletion mutants of the capsid protein to assemble into VLPs in insect cell cultures. Deletion of the N-terminal 20 residues, suggested by the X-ray structure to be involved in a switching mechanism during assembly, did not affect the ability of the mutant capsid protein to self-assemble into 38-nm VLPs with a T=3 icosahedral symmetry. Further deletions in the N-terminal region affected particle assembly. Deletions in the C-terminal regions of the P domain, involved in the interactions between the P and S domains, did not block the assembly process, but they affected the size and stability of the particles. Mutants carrying three internal deletion mutations in the P domain, involved in maintaining dimeric interactions, produced significantly larger 45-nm particles, albeit in low yields. The complete removal of the protruding domain resulted in the formation of smooth particles with a diameter that is slightly smaller than the 30-nm diameter expected from the rNV structure. These studies indicate that the shell domain of the NV capsid protein contains everything required to initiate the assembly of the capsid, whereas the entire protruding domain contributes to the increased stability of the capsid by adding intermolecular contacts between the dimeric subunits and may control the size of the capsid.
Symptoms of musculoskeletal disorders in stage rally drivers and co-drivers
Authors: Mansfield N J , Marshall J M 
Published: July 2002

Background—During stage rallying, musculoskeletal injuries may be provoked by the high magnitude of vibration and shock to which the driver and co-driver are exposed. Drivers and co-drivers experience similar exposure to whole body mechanical shocks and vibration but different exposure to hand/wrist stressors.Objectives—To investigate by a questionnaire study the prevalence of symptoms of musculoskeletal injuries after rallying in 13 professional and 105 amateur stage rally competitors.Methods—The self administered questionnaire investigated whole body and hand/wrist symptoms of musculoskeletal injury. It was loosely based on the Nordic design.Results—91% of participants who competed or tested for more than 10 days a year (n=90) reported discomfort in at least one body area after rallying. Problems in the lumbar spine (70%), cervical spine (54%), shoulders (47%), and thoracic spine (36%) were the most common. There was a higher prevalence of cervical spine discomfort for co-drivers (62%) than for drivers (46%). Conversely, there was higher prevalence of discomfort in the hands and wrists for drivers (32%) than co-drivers (9%). The prevalence of low back pain in rally participants is higher than that generally reported for workers exposed to whole body vibration. The prevalence of discomfort in the hand and wrist for rally drivers is similar to that previously reported for Formula 1 drivers.Conclusions—Most stage rally drivers and co-drivers report symptoms of musculoskeletal injury. It is logical to relate the high prevalence of symptoms of injury to the extreme environment of the rally car.
Acid regulates inflammatory response in a rat model of induction of gastric ulcer recurrence by interleukin 1β
Authors: Watanabe T , Higuchi K , Tominaga K , Fujiwara Y , Arakawa T 
Published: July 2002

BACKGROUNDIn a previous study we showed that interleukin 1β (IL-1β) caused recurrence of gastric ulcers in rats, and that adhesion molecules (intercellular adhesion molecule 1 and leucocytic β2 integrins) play a role in this recurrence. Although gastric acid plays an important role in many types of gastric injuries, including peptic ulcer recurrence, the mechanism(s) remains unclear.AIMSTo examine the involvement of gastric acid in induction of ulcer recurrence by IL-1β, and to investigate the role of gastric acid in inflammatory responses during ulcer recurrence.METHODSRats with healed ulcers were used. Rats were given 1 μg/kg IL-1β intraperitoneally. Another group of rats was given 20 mg/kg omeprazole for three days to inhibit acid secretion, and received IL-1β 20 hours after the first administration of omeprazole. They were then given 0.15 N HCl or vehicle at 0, 12, 24, and 36 hours after IL-1β treatment. Some rats were given acid alone at the same time points. Expression of adhesion molecules was examined immunohistochemically and concentrations of IL-1β and tumour necrosis factor α (TNF-α) were measured by ELISA in scar tissue 24 hours after IL-1β treatment.RESULTSIL-1β increased expression of adhesion molecules and concentrations of IL-1β and TNF-α in scar tissue by 24 hours after IL-1β treatment, and nine of 11 healed ulcers had recurred by 48 hours. Omeprazole inhibited the effects of IL-1β. HCl acid abolished the inhibitory effects of omeprazole. Acid alone affected neither expression of adhesion molecules nor cytokine concentrations, and did not cause recurrence.CONCLUSIONSGastric acid is required for recurrence of gastric ulcers caused by IL-1β, and gastric acid stimulates the inflammatory process in scarred mucosa during ulcer recurrence.
Acute vascular responses to the frequency of vibration transmitted to the hand
Authors: Bovenzi Massimo , Lindsell Christopher J , Griffin Michael J 
Published: July 2002

OBJECTIVESTo investigate the acute effects of the frequency of hand transmitted vibration on finger circulation. A further aim was to investigate whether the frequency weighting assumed in current standards for hand transmitted vibration reflects the haemodynamic changes which occur in the fingers exposed to vibration with different frequencies but with the same frequency weighted acceleration magnitude.METHODSFinger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men. With a static load of 10 N, the right hand was exposed for 15 minutes to the following root mean square (rms) acceleration magnitudes and frequencies of vertical vibration: 5.5 m/s2at 16 Hz; 11 m/s2at 31.5 Hz; 22 m/s2at 63 Hz; 44 m/s2at 125 Hz; and 88 m/s2at 250 Hz. These exposures to vibration produce the same frequency weighted acceleration magnitude (5.5 m/s2rms) according to the frequency weighting included in the international standard ISO 5349. A control condition consisted of exposure to the static load only. Finger circulation was measured before application of the vibration and static load and at fixed intervals during exposure to vibration and a 45 minute recovery period.RESULTSNo significant changes in finger circulation were found with only the static load. The FST did not change significantly during or after acute exposure to vibration. In the vibrated right finger, exposures to vibration with frequencies of 31.5–250 Hz provoked a greater reduction in FBF than did vibration of 16 Hz or the static load only. In the non-vibrated left finger, the FBF measured with vibration at each frequency of 63–250 Hz was significantly lower than that measured with static load only. The reduction in FBF during exposure to vibration with any frequency was stronger in the vibrated finger than in the non-vibrated finger. In both fingers, there was a progressive decrease in FBF after the end of exposure to vibration with frequencies of 31.5–250 Hz. The higher the frequency of vibration, the stronger the decrease in FBF in both fingers during recovery.CONCLUSIONSAcute exposures to vibration with equal frequency weighted magnitude reduce the FBF in both vibrated and non-vibrated fingers for frequencies between 31.5 and 250 Hz. The extent of digital vasoconstriction after exposure to vibration increases with increasing frequency. The frequency weighting given in current standards tends to overestimate the vasoconstriction associated with acute exposures to vibration frequencies around 16 Hz.