bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Balanced Type 1/Type 2 Response Is Associated with Long-Term Nonprogressive Human Immunodeficiency Virus Type 1 Infection
Authors: Imami Nesrina , Pires Antonio , Hardy Gareth , Wilson Jamie , Gazzard Brian , Gotch Frances 
Published: October 2002

ABSTRACTPrevious reports have emphasized the requirements for strong type 1 cell-mediated responses in the control of human immunodeficiency virus type 1 (HIV-1). HIV-1 Gag p24-specific CD4 helper T-lymphocyte (HTL) responses have been shown to inversely correlate with viral burden in HIV-1-infected individuals. In this study, peripheral blood mononuclear cells from 70 individuals with chronic progressive HIV-1 infection (clinical progressors), 10 clinical nonprogressors, and 3 immunologically discordant progressors were assessed for HTL proliferation and type 1/type 2 cytokine production. Clinical progressors lacked functional HIV-1-specific HTLs with proliferative and cytokine-producing capacity. Clinical nonprogressors were found to respond to a wide range of HIV-1 antigens from different clades, producing both type 1 and type 2 cytokines. Immunologically discordant progressors responded strongly to clade B Gag p24 with a type 1 cytokine profile but not to other antigens. Thus, in contrast to clinical nonprogressors, neither progressors nor immunologically discordant progressors secreted interleukin-4 (IL-4) in response to HIV-1 antigens. Both clinical nonprogressors and immunologically discordant progressors responded broadly to B clade Gag p24-overlapping peptides. However, IL-4 production in the nonprogressors was restricted to a limited number of p24 peptides. No HIV-1-specific T-cell responses were seen in 20 seronegative controls. Additionally, we observed a rapid type 1 to type 2 shift in the response of one immunologically discordant progressor upon onset of clinical symptoms. These results suggest that a balanced type 1/type 2 profile correlates with successful long-term control of HIV-1.
Human Monoclonal Antibodies Specific for Conformation-Sensitive Epitopes of V3 Neutralize Human Immunodeficiency Virus Type 1 Primary Isolates from Various Clades
Authors: Gorny Miroslaw K. , Williams Constance , Volsky Barbara , Revesz Kathy , Cohen Sandra , Polonis Victoria R. , Honnen William J. , Kayman Samuel C. , Krachmarov Chavdar , Pinter Abraham , Zolla-Pazner Susan 
Published: October 2002

ABSTRACTThe epitopes of the V3 domain of the human immunodeficiency virus type 1 (HIV-1) gp120 glycoprotein have complex structures consisting of linear and conformational antigenic determinants. Anti-V3 antibodies (Abs) recognize both types of elements, but Abs which preferentially react to the conformational aspect of the epitopes may have more potent neutralizing activity against HIV-1, as recently suggested. To test this hypothesis, human anti-V3 monoclonal Abs (MAbs) were selected using a V3 fusion protein (V3-FP) which retains the conformation of the third variable region. The V3-FP consists of the V3JR-CSFsequence inserted into a truncated form of murine leukemia virus gp70. Six human MAbs which recognize epitopes at the crown of the V3 loop were selected with the V3-FP. They were found to react more strongly with molecules displaying conformationally intact V3 than with linear V3 peptides. In a virus capture assay, these MAbs showed cross-clade binding to native, intact virions of clades A, B, C, D, and F. No binding was found to isolates from subtype E. The neutralizing activity of MAbs against primary isolates was determined in three assays: the GHOST cell assay, a phytohemagglutinin-stimulated peripheral blood mononuclear cell assay, and a luciferase assay. While these new MAbs displayed various degrees of activity, the pattern of cross-clade neutralization of clades A, B, and F was most pronounced. The neutralization of clades C and D viruses was weak and sporadic, and neutralization of clade E by these MAbs was not detected. Analysis by linear regression showed a highly significant correlation (P< 0.0001) between the strength of binding of these anti-V3 MAbs to intact virions and the percent neutralization. These studies demonstrate that human MAbs to conformation-sensitive epitopes of V3 display cross-clade reactivity in both binding to native, intact virions and neutralization of primary isolates.
Characterization of the
cis-
Acting Contributions to Avian Hepadnavirus RNA Encapsidation
Authors: Ostrow Kristin M. , Loeb Daniel D. 
Published: October 2002

ABSTRACT

Previous analysis of duck hepatitis B virus (DHBV) indicated the presence of at least two
cis
-acting sequences required for efficient encapsidation of its pregenomic RNA (pgRNA), ε and region II. ε, an RNA stem-loop near the 5′ end of the pgRNA, has been characterized in detail, while region II, located in the middle of the pgRNA, is not as well defined. Our initial aim was to identify the sequence important for the function of region II in DHBV. We scanned region II and the surrounding sequence by using a quantitative encapsidation assay. We found that the sequence between nucleotides (nt) 438 and 720 contributed to efficient pgRNA encapsidation, while the sequence between nt 538 and 610 made the largest contribution to encapsidation. Additionally, deletions between the two encapsidation sequences, ε and region II, had variable effects on encapsidation, while substitutions of heterologous sequence between ε and region II disrupted the ability of the pgRNA to be encapsidated efficiently. Overall, these data indicate that the intervening sequences between ε and region II play a role in encapsidation. We also analyzed heron hepatitis B virus (HHBV) for the presence of region II and found features similar to DHBV: a broad region necessary for efficient encapsidation that contained a critical region II sequence. Furthermore, we analyzed variants of DHBV that were substituted with HHBV sequence over region II and found that the chimeras were not fully functional for RNA encapsidation. These results indicate that sequences within region II may need to be compatible with other viral components in order to function in pgRNA encapsidation.
In Vivo Association of Adenovirus Large E1A Protein with the Human Mediator Complex in Adenovirus-Infected and -Transformed Cells
Authors: Wang Gang , Berk Arnold J. 
Published: October 2002

ABSTRACT
The adenovirus large E1A protein activates transcription from early viral promoters by a mechanism that requires a forty amino acid zinc finger activation domain in E1A conserved region 3 (CR3). Recent results indicate that activation by a Gal4 DNA-binding domain-E1A-CR3 fusion requires an interaction between the E1A-CR3 zinc finger and the Sur2 subunit of the mammalian Mediator (of transcription) complex. Although several host proteins have been shown to bind stably to E1A proteins in adenovirus-infected and -transformed cells, an in vivo interaction with Mediator complex subunits has not been described previously. Using immunoprecipitation and gel filtration analyses of nuclear extracts prepared from HeLa cells infected with adenovirus 5 or mutants that express either large or small E1A specifically and from adenovirus 5-transformed cells, we report here that large E1A, but not small E1A, binds to Mediator complex in vivo. Only ∼1 to 10% of large E1A is bound to Mediator complex at 18 h postinfection and in transformed cells, probably explaining why Mediator complex subunits were not identified among cellular E1A-binding proteins described earlier. Surprisingly, even though extracted Mediator can quantitatively bind to an E1A-CR3 affinity column, only on the order of 1% of cellular Mediator complex is bound by E1A in vivo. Much of the large E1A bound to Mediator in 293 cells is in a stable complex that includes RNA polymerase II, leading us to suggest that the interaction of E1A-CR3 with Mediator stabilizes the interaction of Mediator with the polymerase. This stabilization of the interaction between Mediator and RNA polymerase II may contribute to the mechanism of activation by E1A-CR3.
Potent and Specific Inhibition of Human Immunodeficiency Virus Type 1 Replication by RNA Interference
Authors: Coburn Glen A. , Cullen Bryan R. 
Published: October 2002

ABSTRACT
Synthetic small interfering RNAs (siRNAs) have been shown to induce the degradation of specific mRNA targets in human cells by inducing RNA interference (RNAi). Here, we demonstrate that siRNA duplexes targeted against the essential Tat and Rev regulatory proteins encoded by human immunodeficiency virus type 1 (HIV-1) can specifically block Tat and Rev expression and function. More importantly, we show that these same siRNAs can effectively inhibit HIV-1 gene expression and replication in cell cultures, including those of human T-cell lines and primary lymphocytes. These observations demonstrate that RNAi can effectively block virus replication in human cells and raise the possibility that RNAi could provide an important innate protective response, particularly against viruses that express double-stranded RNAs as part of their replication cycle.
Upregulation of Surface Feline CXCR4 Expression following Ectopic Expression of CCR5: Implications for Studies of the Cell Tropism of Feline Immunodeficiency Virus
Authors: Willett Brian J. , Cannon Celia A. , Hosie Margaret J. 
Published: October 2002

ABSTRACT

Feline CXCR4 and CCR5 were expressed in feline cells as fusion proteins with enhanced green fluorescent protein (EGFP). Expression of the EGFP fusion proteins was localized to the cell membrane, and surface expression of CXCR4 was confirmed by using a cross-species-reactive anti-CXCR4 monoclonal antibody. Ectopic expression of feline CCR5 enhanced expression of either endogenous feline CXCR4 or exogenous feline or human CXCR4 expressed from a retrovirus vector, indicating that experiments investigating the effect of CCR5 expression on feline immunodeficiency virus (FIV) infection must be interpreted with caution. Susceptibility to infection with cell culture-adapted strains of FIV or to syncytium formation following transfection with a eukaryotic vector expressing an
env
gene from a cell culture-adapted strain of virus correlated with expression of either human or feline CXCR4, whereas feline CCR5 had no effect. In contrast, neither CXCR4 nor CCR5 rendered cells permissive to either productive infection with primary strains of FIV or syncytium formation following transfection with primary
env
gene expression vectors. Screening a panel of Ghost cell lines expressing diverse human chemokine receptors confirmed that CXCR4 alone supported fusion mediated by the FIV Env from cell culture-adapted viruses. CXCR4 expression was upregulated in Ghost cells coexpressing CXCR4 and CCR5 or CXCR4, CCR5, and CCR3, and susceptibility to FIV infection could be correlated with the level of CXCR4 expression. The data suggest that β-chemokine receptors may influence FIV infection by modulating the expression of CXCR4.
Combination of Drugs and Drug-Resistant Reverse Transcriptase Results in a Multiplicative Increase of Human Immunodeficiency Virus Type 1 Mutant Frequencies
Authors: Mansky Louis M. , Pearl Dennis K. , Gajary Lisa C. 
Published: October 2002

ABSTRACT
Replication of drug-resistant human immunodeficiency virus type 1 (HIV-1) in the presence of drug can lead to the failure of antiretroviral drug treatment. Drug failure is associated with the accumulation of drug resistance mutations. Previous studies have shown that 3′-azido-3′-deoxythymidine (AZT), (−)2′,3′-dideoxy-3′-thiacytidine (3TC), and AZT-resistant HIV-1 reverse transcriptase (RT) can increase the virus in vivo mutation rate. In this study, the combined effects of drug-resistant RT and antiretroviral drugs on the HIV-1 mutant frequency were determined. In most cases, a multiplicative effect was observed with AZT-resistant or AZT/3TC dually resistant RT and several drugs (i.e., AZT, 3TC, hydroxyurea, and thymidine) and led to increases in the odds of recovering virus mutants to over 20 times that of the HIV-1 mutant frequency in the absence of drug or drug-resistance mutations. This observation indicates that HIV-1 can mutate at a significantly higher rate when drug-resistant virus replicates in the presence of drug. These increased mutant frequencies could have important implications for HIV-1 population dynamics and drug therapy regimens.
Hepatitis C Virus Core Protein Leads to Immune Suppression and Liver Damage in a Transgenic Murine Model
Authors: Soguero Carolina , Joo Myungsoo , Chianese-Bullock Kimberly A. , Nguyen Duong Tony , Tung Kenneth , Hahn Young S. 
Published: October 2002

ABSTRACTHepatitis C virus (HCV) is remarkably efficient in establishing persistent infection, possibly mediated by an impaired immune response to HCV infection. There is compelling evidence that HCV can infect immune cells, such as macrophages, B cells, and T cells. It has been previously reported that HCV core, the first protein expressed during the early phase of viral infection, contains the immunomodulatory function of suppressing host immune responses. This altered function of immune cells caused by HCV infection may explain the ineffective immune response to HCV. To further characterize the immunomodulatory role of HCV core in vivo, we generated transgenic (TG) mice by directing the expression of core protein to T lymphocytes by using the CD2 promoter. T-lymphocyte responses, including the production of gamma interferon and interleukin-2, were significantly diminished in these mice compared to their non-TG littermates. The inhibition of T-lymphocyte responsiveness may be due to the increased susceptibility of peripheral T lymphocytes to Fas-mediated apoptosis. Surprisingly, significant lymphocyte infiltration was observed in the portal tracts of livers isolated from core TG mice, associated with increasing serum alanine aminotransferase levels. Moreover, no intrahepatic lymphocytes or liver damage was found in non-TG littermates and core TG mice bred to Fas-deficientlprmice. These results suggest that HCV core drives liver injury by increasing Fas-mediated apoptosis and liver infiltration of peripheral T cells.
The Epstein-Barr Virus SM Protein Is Functionally Similar to ICP27 from Herpes Simplex Virus in Viral Infections
Authors: Boyer Julie L. , Swaminathan Sankar , Silverstein Saul J. 
Published: October 2002

ABSTRACT
The herpes simplex virus type 1 (HSV-1) ICP27 protein is an essential RNA-binding protein that shuttles between the nucleus and cytoplasm to increase the cytoplasmic accumulation of viral late mRNAs. ICP27 homologs have been identified in each of the herpesvirus subfamilies, and accumulating evidence indicates that homologs from the gammaherpesvirus subfamily function similarly to ICP27. In particular, the Epstein-Barr virus (EBV) SM protein posttranscriptionally regulates gene expression, binds RNA in vitro and in vivo, and shuttles between the nucleus and cytoplasm. To determine if these two proteins function through a common mechanism, the ability of EBV SM to complement the growth defect of an HSV-1 ICP27-null virus was examined in a transient-expression assay. ICP27 stimulated the growth of the null mutant more efficiently than did SM, but the ability of SM to compensate for the ICP27 defects suggests conservation of common functions. To assay for complementation in the context of a viral infection, the growth properties of an HSV recombinant expressing SM in an ICP27-null background were analyzed. SM stimulated growth of the recombinant, although this growth was reduced by comparison to that of an ICP27-expressing virus. By contrast, an HSV recombinant expressing an SM mutant allele defective for transactivation activity and nucleocytoplasmic shuttling did not grow at all. These results suggest that SM and ICP27 may regulate gene expression through a common pathway that is evolutionarily conserved in herpesviruses.
Baculovirus Transregulator IE1 Requires a Dimeric Nuclear Localization Element for Nuclear Import and Promoter Activation
Authors: Olson Victoria A. , Wetter Justin A. , Friesen Paul D. 
Published: October 2002

ABSTRACT

Immediate-early protein IE1 is a principal regulator of viral transcription and a contributor to origin-specific DNA replication of the baculovirus
Autographa californica
multicapsid nucleopolyhedrovirus (Ac
M
NPV). Since these viral functions involve interaction of dimeric IE1 with palindromic homologous region (
hr
) enhancer-origin elements of the Ac
M
NPV genome within the nucleus, it is presumed that proper nuclear transport of IE1 is essential for productive infection. To investigate the mechanisms of IE1 nuclear import, we analyzed the effect of site-directed mutations on IE1 subcellular distribution. As demonstrated by fluorescence microscopy and biochemical fractionation of plasmid-transfected cells, wild-type IE1 localized predominantly to the nucleus. Substitution or deletion of amino acid residues within a positively charged domain (residues 534 to 538) adjacent to IE1's oligomerization motif impaired nuclear import and caused loss of transactivation. Moreover, upon coexpression, these import-defective mutations prevented nuclear entry of wild-type IE1. In contrast, double-mutated IE1 defective for both nuclear import and dimerization failed to block nuclear entry or transactivation by wild-type IE1. Thus, import-defective IE1 dominantly interfered with wild-type IE1 by direct interaction and cytosolic trapping. Collectively, our data indicate that the small basic domain encompassing residues R
537
and R
538
constitutes a novel nuclear localization element that functions only upon IE1 dimerization. These findings support a model wherein IE1 oligomerizes within the cytosol as a prerequisite for nuclear entry and subsequent high-affinity interaction with the symmetrical binding sites comprising Ac
M
NPV
hr
enhancer-origin elements.
Growth of Rotaviruses in Primary Pancreatic Cells
Authors: Coulson Barbara S. , Witterick Paul D. , Tan Yan , Hewish Marilyn J. , Mountford Joanne N. , Harrison Leonard C. , Honeyman Margo C. 
Published: October 2002

ABSTRACT
Rotavirus infection in children at risk of developing type 1 diabetes has been temporally associated with development of pancreatic islet autoantibodies. In this study, nonobese diabetic mice were shown to be susceptible to rhesus rotavirus infection and pancreatic islets from nonobese diabetic mice, nonobese diabetes-resistant mice, fetal pigs, and macaque monkeys supported various degrees of rotavirus growth. Human rotaviruses replicated in monkey islets only. This islet susceptibility shows that rotavirus infection of the pancreas in vivo might be possible.
An audit of first aid qualifications and knowledge among team officials in two English youth football leagues: a preliminary study
Authors: Cunningham A 
Published: October 2002

Objectives: To determine if youth football officials responsible for dealing with injuries have appropriate first aid qualifications and knowledge?Methods: Information was collected from two youth football leagues by questionnaire. First aiders were asked to provide details of their qualifications and their response from a list of alternatives to an injury scenario.Results: Fifty two of 86 respondents did not have a current first aid qualification. Only 12% and 38% respectively gave the correct response to the injury scenarios “player choking” and “player unconscious”. Health and injury records for the players were kept by 40% and 19% of teams. Written parental consent to emergency treatment was obtained by 30%.Conclusion: This preliminary study shows an obligation on teams who do not possess a qualified first aider to evaluate their legal and moral responsibilities to their players. The Football Association and Health and Safety Executive should produce a list of recommended equipment, facilities, and first aid qualified personnel to which teams should have access at games and training sessions. Providers of first aid training should reassess their teaching of the management of the choking and unconscious casualty.
Children are not goldfish—mark/recapture techniques and their application to injury data
Authors: Jarvis Stephen N , Lowe Philip J , Avery Alison , Levene Sara , Cormack Richard M 
Published: October 2002

Objectives—Mark/recapture (or capture-recapture) is a simple technique commonly applied to estimate the hypothetical total (including undercount) in a register composed of cases from two or more independent and separately incomplete case lists. This paper seeks to illustrate serious drawbacks in the use of the mark/recapture technique when applied to injuries.Setting and subjects—Northumbrian children under 15 years of age who were seriously injured in motor vehicle accidents (MVAs) over a five year period ascertained from two data sources: police reports and hospital inpatient records.Methods—Individuals (n) appearing in both police (S) and hospital (H) case lists are identified using various matching criteria. The separate and combined influence of age, sex, and casualty class (cyclist, passengers, pedestrians) on the probability of such matching is estimated using multivariate techniques. The hypothetical total incidence of child MVA victims (N) is calculated from N = (S × H)/n.Main outcomes—Estimates of the incidences of “serious” injuries in MVAs under various conditions of stratification and matching. The overall procedure is tested for conformity with accepted criteria for valid use of mark/recapture.Results—About one third of the 1009 police and 836 hospital records could be exactly matched. There were significant variations in matching proportions by class of accident (pedestrianvpassengervcyclist). This selective recapture or “heterogeneity” was not affected by sex, but was independently influenced by the age of the child. Further uncertainty was introduced when matching criteria were slightly relaxed. Estimates of the total population of children with serious injuries vary accordingly from 1729 to 2743. A number of plausible reasons why these two data sources might not be unbiased or mutually independent samples of the total target population are proposed as explanations for this heterogeneity.Conclusion—This typical example of two sample mark/recapture estimation in an epidemiological setting can be shown to violate virtually all the requirements for valid use of the technique. Very little can be deduced accurately about the scale or characteristics of an unobserved group by the use of mark/recapture applied to two overlapping health event registers.
Testing the impact attenuation of loose-fill playground surfaces
Authors: Mack Mick G , Sacks Jeffrey J , Thompson Donna 
Published: October 2002

Objectives—Our objective was to measure the impact attenuation performance of five types of loose-fill playground surfaces at a variety of drop heights, material depths, and conditions.Methods—In a laboratory setting, an instrumented head form was dropped on varying depths of loose-fill materials at one foot height increments until critical deceleration values were exceeded. The effects of test box size, material temperature, and compression were also studied.Results—Data suggest that a larger test box size influences test results. Uncompressed materials performed quite unexpectedly, that is, resilience did not necessarily increase with increasing depth of material and temperature did not have uniform effects. Compression before testing improved consistency of results.Conclusion—The current standard test procedure (ASTM F1292) appears problematic for loose-fill materials. Our results indicate that (1) shredded rubber was the best performer; (2) there was little difference between sand, wood fibers, and wood chips; and (3) pea gravel had the worst performance, making it a poor choice for playground surfacing.