bluuebunny/crossref_metadata_2025 huggingface dataset:
Two Subclasses of Kaposi's Sarcoma-Associated Herpesvirus Lytic Cycle Promoters Distinguished by Open Reading Frame 50 Mutant Proteins That Are Deficient in Binding to DNA
Authors: Chang Pey-Jium , Shedd Duane , Miller George
Published: July 2005

A transcriptional activator encoded in open reading frame 50 (ORF50) of the Kaposi's sarcoma-associated herpesvirus (KSHV) genome initiates the viral lytic cycle. Here we classify four lytic cycle genes on the basis of several characteristics of the ORF50 response elements (ORF50 REs) in their promoters: nucleotide sequence homology, the capacity to bind ORF50 protein in vitro, the ability to bind the cellular protein RBP-Jκ in vitro, and the capacity to confer activation by DNA binding-deficient mutants of ORF50 protein. ORF50 expressed in human cells binds the promoters of PAN and K12 but does not bind ORF57 or vMIP-1 promoters. Conversely, the RBP-Jκ protein binds ORF57 and vMIP-1 but not PAN or K12 promoters. DNA binding-deficient mutants of ORF50 protein differentiate these two subclasses of promoters in reporter assays; the PAN and K12 promoters cannot be activated, while the ORF57 and vMIP-1 promoters are responsive. Although DNA binding-deficient mutants of ORF50 protein are defective in activating direct targets, they are nonetheless capable of activating the lytic cascade of KSHV. Significantly, DNA binding-deficient ORF50 mutants are competent to autostimulate expression of endogenous ORF50 and to autoactivate ORF50 promoter reporters. The experiments show that ORF50 protein activates downstream targets by at least two distinct mechanisms: one involves direct binding of ORF50 REs in promoter DNA; the other mechanism employs interactions with the RBP-Jκ cellular protein bound to promoter DNA in the region of the ORF50 RE. The DNA binding-deficient mutants allow classification of ORF50-responsive genes and will facilitate study of the several distinct mechanisms of activation of KSHV lytic cycle genes that are under the control of ORF50 protein.
Evaluating the Immunogenicity of a Disulfide-Stabilized, Cleaved, Trimeric Form of the Envelope Glycoprotein Complex of Human Immunodeficiency Virus Type 1
Authors: Beddows Simon , Schülke Norbert , Kirschner Marc , Barnes Kelly , Franti Michael , Michael Elizabeth , Ketas Thomas , Sanders Rogier W. , Maddon Paul J. , Olson William C. , Moore John P.
Published: July 2005

The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) complex comprises three gp120 exterior glycoproteins each noncovalently linked to a gp41 transmembrane glycoprotein. Monomeric gp120 proteins can elicit antibodies capable of neutralizing atypically sensitive test viruses in vitro, but these antibodies are ineffective against representative primary isolates and the gp120 vaccines failed to provide protection against HIV-1 transmission in vivo. Alternative approaches to raising neutralizing antibodies are therefore being pursued. Here we report on the antibody responses generated in rabbits against a soluble, cleaved, trimeric form of HIV-1
JR-FL
Env. In this construct, the gp120 and gp41 moieties are covalently linked by an intermolecular disulfide bond (SOS gp140), and an I559P substitution has been added to stabilize gp41-gp41 interactions (SOSIP gp140). We investigated the value of DNA priming and compared the use of membrane-bound and soluble priming antigens and of repeat boosting with soluble and particulate protein antigen. Compared to monomeric gp120, SOSIP gp140 trimers elicited approximately threefold lower titers of anti-gp120 antibodies. Priming with DNA encoding a membrane-bound form of the SOS gp140 protein, followed by several immunizations with soluble SOSIP gp140 trimers, resulted in antibodies capable of neutralizing sensitive strains at high titers. A subset of these sera also neutralized, at lower titers, HIV-1
JR-FL
and some other primary isolates in pseudovirus and/or whole-virus assays. Neutralization of these viruses was immunoglobulin mediated and was predominantly caused by antibodies to gp120 epitopes, but not the V3 region.
A Human T-Cell Leukemia Virus Type 1 Regulatory Element Enhances the Immunogenicity of Human Immunodeficiency Virus Type 1 DNA Vaccines in Mice and Nonhuman Primates
Authors: Barouch Dan H. , Yang Zhi-yong , Kong Wing-pui , Korioth-Schmitz Birgit , Sumida Shawn M. , Truitt Diana M. , Kishko Michael G. , Arthur Janelle C. , Miura Ayako , Mascola John R. , Letvin Norman L. , Nabel Gary J.
Published: July 2005

Plasmid DNA vaccines elicit potent and protective immune responses in numerous small-animal models of infectious diseases. However, their immunogenicity in primates appears less potent. Here we investigate a novel approach that optimizes regulatory elements in the plasmid backbone to improve the immunogenicity of DNA vaccines. Among various regions analyzed, we found that the addition of a regulatory sequence from the R region of the long terminal repeat from human T-cell leukemia virus type 1 (HTLV-1) to the cytomegalovirus (CMV) enhancer/promoter increased transgene expression 5- to 10-fold and improved cellular immune responses to human immunodeficiency virus type 1 (HIV-1) antigens. In cynomolgus monkeys, DNA vaccines containing the CMV enhancer/promoter with the HTLV-1 R region (CMV/R) induced markedly higher cellular immune responses to HIV-1 Env from clades A, B, and C and to HIV-1 Gag-Pol-Nef compared with the parental DNA vaccines. These data demonstrate that optimization of specific regulatory elements can substantially improve the immunogenicity of DNA vaccines encoding multiple antigens in small animals and in nonhuman primates. This strategy could therefore be explored as a potential method to enhance DNA vaccine immunogenicity in humans.
Efficient Axonal Localization of Alphaherpesvirus Structural Proteins in Cultured Sympathetic Neurons Requires Viral Glycoprotein E
Authors: Ch'ng T. H. , Enquist L. W.
Published: July 2005

Pseudorabies virus (PRV) glycoprotein E (gE) is a type I viral membrane protein that facilitates the anterograde spread of viral infection from the peripheral nervous system to the brain. In animal models, a gE-null mutant infection spreads inefficiently from presynaptic neurons to postsynaptic neurons (anterograde spread of infection). However, the retrograde spread of infection from post- to presynaptic neurons remains unaffected. Here we show that gE is required for wild-type localization of viral structural proteins in axons of infected neurons. During a gE-null PRV infection, a subset of viral glycoproteins, capsids, and tegument proteins enter and localize to the axon inefficiently. This defect is most obvious in the distal axon and growth cones. However, axonal entry and localization of other viral membrane proteins and endogenous cellular proteins remains unaffected. Neurons infected with gE-null mutants produce wild-type levels of viral structural proteins and infectious virions in the cell body. Our results indicate that reduced axonal targeting of viral structural proteins is a compelling explanation for the lack of anterograde spread in neural circuits following infection by a gE-null mutant.
Differential Susceptibility to Human Immunodeficiency Virus Type 1 Infection of Myeloid and Plasmacytoid Dendritic Cells
Authors: Smed-Sörensen Anna , Loré Karin , Vasudevan Jayanand , Louder Mark K. , Andersson Jan , Mascola John R. , Spetz Anna-Lena , Koup Richard A.
Published: July 2005

Human immunodeficiency virus type 1 (HIV-1) infection of dendritic cells (DCs) plays an important role in HIV-1 transmission and pathogenesis. Here, we studied the susceptibility of ex vivo-isolated CD11c+myeloid DCs (MDCs) and CD123+plasmacytoid DCs (PDCs) to HIV-1 infection and the function of these cells early after infection. Both DC subsets were susceptible to CCR5- and CXCR4-using HIV-1 isolates (BaL and IIIB, respectively). However, MDCs were more susceptible to HIV-1BaLinfection than donor-matched PDCs. In addition, HIV-1BaLinfected MDCs more efficiently than HIV-1IIIB, whereas PDCs were equally susceptible to both isolates. While exposure to HIV-1 alone resulted in only weak maturation of DCs, Toll-like receptor 7/8 ligation induced full maturation in both infected and uninfected DCs. Maturation did not increase HIV-1 replication in infected DCs, and infected DCs retained their ability to produce tumor necrosis factor alpha after stimulation. Both HIV-1 isolates induced alpha interferon production exclusively in PDCs, irrespective of productive infection. In conclusion, PDCs and MDCs were susceptible to HIV-1 infection, but neither displayed functional defects as a consequence of infection. The difference in susceptibility of PDCs and MDCs to HIV-1 may have implications for HIV-1 transmission and DC-mediated transfer of HIV-1 to T cells.
Pathogenicity of Simian-Human Immunodeficiency Virus SHIV-89.6P and SIVmac Is Attenuated in Cynomolgus Macaques and Associated with Early T-Lymphocyte Responses
Authors: Reimann Keith A. , Parker Robert A. , Seaman Michael S. , Beaudry Kristin , Beddall Margaret , Peterson Lauren , Williams Kenneth C. , Veazey Ronald S. , Montefiori David C. , Mascola John R. , Nabel Gary J. , Letvin Norman L.
Published: July 2005

Because most studies of AIDS pathogenesis in nonhuman primates have been performed in Indian-origin rhesus macaques (
Macaca mulatta
), little is known about lentiviral pathogenicity and control of virus replication following infection of alternative macaque species. Here, we report the consequences of simian-human immunodeficiency virus SHIV-89.6P and SIVmac251 infection in cynomolgus (
Macaca fascicularis
) and rhesus macaques of Chinese origin. Compared to the pathogenicity of the same viruses in Indian rhesus macaques, both cynomolgus and Chinese rhesus macaques showed lower levels of plasma virus. By 9 to 10 months after infection, both viruses became undetectable in plasma more frequently in cynomolgus than in either Chinese or Indian rhesus macaques. Furthermore, after SHIV-89.6P infection, CD4
+
T-cell numbers declined less and survival was longer in cynomolgus and Chinese rhesus macaques than in Indian rhesus macaques. This attenuated pathogenicity was associated with gamma interferon ELISPOT responses to Gag and Env that were generated earlier and of higher frequency in cynomolgus than in Indian rhesus macaques. Cynomolgus macaques also developed higher titer neutralizing antibodies against SHIV-89.6 at 10 and 20 weeks postinoculation than Indian rhesus macaques. These studies demonstrate that the pathogenicity of nonhuman primate lentiviruses varies markedly based on the species or geographic origin of the macaques infected and suggest that the cellular immune responses may contribute to the control of pathogenicity in cynomolgus macaques. While cynomolgus and Chinese rhesus macaques provide alternative animal models of lentiviral infection, the lower levels of viremia in cynomolgus macaques limit the usefulness of infection of this species for vaccine trials that utilize viral load as an experimental endpoint.
Parvovirus Nonstructural Proteins Induce an Epigenetic Modification through Histone Acetylation in Host Genes and Revert Tumor Malignancy to Benignancy
Authors: Iseki Hiroyoshi , Shimizukawa Rie , Sugiyama Fumihiro , Kunita Satoshi , Iwama Atsushi , Onodera Masafumi , Nakauchi Hiromitsu , Yagami Ken-ichi
Published: July 2005

Several malignant tumor cells become apoptotic and revert to the benign phenotype upon parvovirus infection. Recently, we demonstrated that the rat parvovirus RPV/UT also induces apoptosis in the rat thymic lymphoma cell line C58(NT)D. However, a minority of cells that escaped apoptosis showed properties different from the parental cells, such as resistance to apoptosis, enhanced cell adherence, and suppressed tumorigenicity. The present study was performed to determine the molecular mechanism of parvovirus-induced phenotypic modification, including oncosuppression. We demonstrated that the nonstructural (NS) proteins of RPV/UT induced apoptosis in C58(NT)D cells and suppressed tumor growth in vivo. Interestingly, NS proteins induced the expression of ciliary neurotrophic factor receptor alpha, which is up-regulated in revertant cell clones, and enhanced histone acetylation of its gene. These results indicate that parvoviral NS regulate host gene expression through histone acetylation, suggesting a possible mechanism of oncosuppression.
Pathogenesis of Human Metapneumovirus Lung Infection in BALB/c Mice and Cotton Rats
Authors: Hamelin Marie-Ève , Yim Kevin , Kuhn Katie H. , Cragin Rose P. , Boukhvalova Marina , Blanco Jorge C. G. , Prince Gregory A. , Boivin Guy
Published: July 2005

Human metapneumovirus (hMPV) is a newly described member of theParamyxoviridaefamily causing acute respiratory tract infections, especially in young children. We studied the pathogenesis of this viral infection in two experimental small animal models (BALB/c mice and cotton rats). Significant viral replication in the lungs of both animals was found following an intranasal challenge of 10850% tissue culture infectious doses (TCID50) and persisted for <2 and <3 weeks in the case of cotton rats and mice, respectively. Peak viral loads were found on day 5 postinfection in both mice (mean of 1.92 × 107TCID50/g lung) and cotton rats (mean of 1.03 × 105TCID50/g). Clinical symptoms consisting of breathing difficulties, ruffled fur, and weight loss were noted in mice only around the time of peak viral replication. Most significant pulmonary inflammatory changes and peak expression of macrophage inflammatory protein 1α, gamma interferon, and RANTES occurred at the time of maximal viral replication (day 5) in both models. Cellular infiltration occurred predominantly around and within alveoli and persisted for at least 21 days in mice, whereas it was more limited in time with more peribronchiolitis in cotton rats. Both animal models would be of great value in evaluating different therapeutic agents, as well as vaccine candidates against hMPV.
Nairovirus RNA Sequences Expressed by a Semliki Forest Virus Replicon Induce RNA Interference in Tick Cells
Authors: Garcia Stephan , Billecocq Agnès , Crance Jean-Marc , Munderloh Ulrike , Garin Daniel , Bouloy Michèle
Published: July 2005

We report the successful infection of the cell line ISE6 derived from
Ixodes scapularis
tick embryos by the tick-borne Hazara virus (HAZV), a nairovirus in the family
Bunyaviridae
. Using a recombinant Semliki Forest alphavirus replicon that replicates in these cells, we were able to inhibit replication of HAZV, and we showed that this blockage is mediated by the replication of the Semliki Forest alphavirus replicon; the vector containing the HAZV nucleoprotein gene in sense or antisense orientation efficiently inhibited HAZV replication. Moreover, expression of a distantly related nucleoprotein gene from Crimean-Congo hemorrhagic fever nairovirus failed to induce HAZV silencing, indicating that the inhibition is sequence specific. The resistance of these cells to replicate HAZV correlated with the detection of specific RNase activity and 21- to 24-nucleotide-long small interfering RNAs. Altogether, these results strongly suggest that pathogen-derived resistance can be established in the tick cells via a mechanism of RNA interference.
Low CD8 T-Cell Proliferative Potential and High Viral Load Limit the Effectiveness of Therapeutic Vaccination
Authors: Wherry E. John , Blattman Joseph N. , Ahmed Rafi
Published: July 2005

Therapeutic vaccination has the potential to boost immune responses and enhance viral control during chronic infections. However, many therapeutic vaccination approaches have fallen short of expectations, and effective boosting of antiviral T-cell responses is not always observed. To examine these issues, we studied the impact of therapeutic vaccination, using a murine model of chronic infection with lymphocytic choriomeningitis virus (LCMV). Our results demonstrate that therapeutic vaccination using a recombinant vaccinia virus expressing the LCMV GP33 CD8 T-cell epitope can be effective at accelerating viral control. However, mice with lower viral loads at the time of vaccination responded better to therapeutic vaccination than did those with high viral loads. Also, the proliferative potential of GP33-specific CD8 T cells from chronically infected mice was substantially lower than that of GP33-specific memory CD8 T cells from mice with immunity to LCMV, suggesting that poor T-cell expansion may be an important reason for suboptimal responses to therapeutic vaccination. Thus, our results highlight the potential positive effects of therapeutic vaccination on viral control during chronic infection but also provide evidence that a high viral load at the time of vaccination and the low proliferative potential of responding T cells are likely to limit the effectiveness of therapeutic vaccination.
Mutations in the Putative Zinc-Binding Motif of UL52 Demonstrate a Complex Interdependence between the UL5 and UL52 Subunits of the Human Herpes Simplex Virus Type 1 Helicase/Primase Complex
Authors: Chen Yan , Carrington-Lawrence Stacy D. , Bai Ping , Weller Sandra K.
Published: July 2005

Herpes simplex virus type 1 (HSV-1) encodes a heterotrimeric helicase-primase (UL5/8/52) complex. UL5 contains seven motifs found in helicase superfamily 1, and UL52 contains conserved motifs found in primases. The contributions of each subunit to the biochemical activities of the complex, however, remain unclear. We have previously demonstrated that a mutation in the putative zinc finger at UL52 C terminus abrogates not only primase but also ATPase, helicase, and DNA-binding activities of a UL5/UL52 subcomplex, indicating a complex interdependence between the two subunits. To test this hypothesis and to further investigate the role of the zinc finger in the enzymatic activities of the helicase-primase, a series of mutations were constructed in this motif. They differed in their ability to complement a UL52 null virus: totally defective, partial complementation, and potentiating. In this study, four of these mutants were studied biochemically after expression and purification from insect cells infected with recombinant baculoviruses. All mutants show greatly reduced primase activity. Complementation-defective mutants exhibited severe defects in ATPase, helicase, and DNA-binding activities. Partially complementing mutants displayed intermediate levels of these activities, except that one showed a wild-type level of helicase activity. These data suggest that the UL52 zinc finger motif plays an important role in the activities of the helicase-primase complex. The observation that mutations in UL52 affected helicase, ATPase, and DNA-binding activities indicates that UL52 binding to DNA via the zinc finger may be necessary for loading UL5. Alternatively, UL5 and UL52 may share a DNA-binding interface.
Envelope Glycoprotein Mutations Mediate Equine Amplification and Virulence of Epizootic Venezuelan Equine Encephalitis Virus
Authors: Greene Ivorlyne P. , Paessler Slobodan , Austgen Laura , Anishchenko Michael , Brault Aaron C. , Bowen Richard A. , Weaver Scott C.
Published: July 2005

Epidemics of Venezuelan equine encephalitis (VEE) result from high-titer equine viremia of IAB and IC subtype viruses that mediate increased mosquito transmission and spillover to humans. Previous genetic studies suggest that mutations in the E2 envelope glycoprotein allow relatively viremia-incompetent, enzootic subtype ID strains to adapt for equine replication, leading to VEE emergence. To test this hypothesis directly, chimeric VEEV strains containing the genetic backbone of enzootic subtype ID strains and the partial envelope glycoprotein genes of epizootic subtype IC and IAB strains, as well as reciprocal chimeras, were used for experimental infections of horses. Insertion of envelope genes from two different, closely related enzootic subtype ID strains into the epizootic backbones resulted in attenuation, demonstrating that the epizootic envelope genes are necessary for the equine-virulent and viremia-competent phenotypes. The partial epizootic envelope genes introduced into an enzootic ID backbone were sufficient to generate the virulent, viremia-competent equine phenotype. These results indicate that a small number of envelope gene mutations can generate an equine amplification-competent, epizootic VEEV from an enzootic progenitor and underscore the limitations of small animal models for evaluating and predicting the epizootic phenotype.
Analysis of Human Immunodeficiency Virus Type 1 Gag Ubiquitination
Authors: Gottwein Eva , Kräusslich Hans-Georg
Published: July 2005

Ubiquitin is important for the release of human immunodeficiency virus type 1 (HIV-1) and several other retroviruses, but the functional significance of Gag ubiquitination is unknown. To address this problem, we decided to analyze Gag ubiquitination in detail. A low percentage of the HIV-1 p6 protein has previously been shown to be ubiquitinated, and published mutagenesis data suggested that Gag ubiquitination is largely lost upon mutation of the two lysine residues in p6. In this study, we show that Gag proteins lacking the p6 domain or the two lysine residues within p6 are ubiquitinated at levels comparable to those of the wild-type Gag protein. We detected monoubiquitinated forms of the matrix (MA), capsid (CA), and nucleocapsid (NC) proteins in mature virus preparations. Protease digestion of Gag polyproteins extracted from immature virions indicated that ubiquitinated MA, CA, and possibly NC are as abundant as ubiquitinated p6. The HIV-1 late-domain motifs PTAP and LRSLF were not required for Gag ubiquitination, and mutation of the PTAP motif even resulted in an increase in the amount of Gag-Ub conjugates detected. Finally, at steady state, ubiquitinated Gag proteins were not enriched in either membrane-associated or virus-derived Gag fractions. In summary, these results indicate that HIV-1 Gag can be monoubiquitinated in all domains and that ubiquitination of lysine residues outside p6 may thus contribute to viral release and/or infectivity.
Compartmentalization of Hepatitis C Virus Quasispecies in Blood Mononuclear Cells of Patients with Mixed Cryoglobulinemic Syndrome
Authors: Zehender Gianguglielmo , De Maddalena Chiara , Bernini Flavia , Ebranati Erika , Monti Giuseppe , Pioltelli Piero , Galli Massimo
Published: July 2005

The aim of this study was to investigate the quasispecies heterogeneity of hepatitis C virus (HCV) in the plasma, cryoprecipitate, and peripheral lymphocytes of chronically infected HCV patients with mixed cryoglobulinemia (MC). We studied 360 clones from 10 HCV-positive patients with MC and 8 age-, gender- and HCV genotype-matched subjects with chronic HCV infection but without MC. A partial nucleotide sequence encompassing the E1/E2 region, including hypervariable region 1 (HVR1), was amplified and cloned from plasma, cryoprecipitates, and peripheral blood mononuclear cells (PBMC), and the genetic diversity and complexity and synonymous and nonsynonymous substitution rates were determined. Heterogeneous selection pressure at codon sites was evaluated. Compartmentalization was estimated by phylogenetic and phenetic (Mantel's test) approaches. The patients with MC had 3.3 times lower nonsynonymous substitution rates (1.7 versus 5.7 substitutions/100 sites). Among the subjects with HCV genotype 1, the MC patients had significantly less complexity than the controls, whereas the diversity and complexity were similar in the genotype 2 patients and controls. Site-specific selection analysis confirmed the low frequency of MC patients showing positive selection. There was a significant correlation between positive selection and the infecting HCV genotype. The quasispecies were less heterogeneous in PBMC than in plasma. Significant compartmentalization of HCV quasispecies was observed in the PBMC of four of nine subjects (three with MC) and seven of nine cryoprecipitates. In one subject with MC, we detected a 5-amino-acid insertion at codons 385 to 389 of HVR1. Our results suggest reduced quasispecies heterogeneity in MC patients that is related to a low selection pressure which is probably due to an impaired immune response, the HCV genotype, and/or the duration of the infection. The frequent HCV quasispecies compartmentalization in patients' PBMC suggests a possible pathogenetic significance.
Regulation of Human Immunodeficiency Virus Type 1 Gene Expression by Clade-Specific Tat Proteins
Authors: Desfosses Yan , Solis Mayra , Sun Qiang , Grandvaux Nathalie , Van Lint Carine , Burny Arsene , Gatignol Anne , Wainberg Mark A. , Lin Rongtuan , Hiscott John
Published: July 2005

The major group of human immunodeficiency virus type 1 (HIV-1) strains that comprise the current global pandemic have diversified during their worldwide spread into at least 10 distinct subtypes, or clades. Subtype C predominates in sub-Saharan Africa and is responsible for the majority of worldwide HIV-1 infections, subtype B predominates in North America and Europe, and subtype E is prevalent in Southeast Asia. Significant amino acid variations have been observed among the clade-specific Tat proteins. For the present study, we examined clade-specific interactions between Tat, transactivation-responsive (TAR) element, and P-TEFb proteins and how these interactions may modulate the efficiency of HIV-1 transcription. Clade-specific Tat proteins significantly modified viral gene expression. Tat proteins derived from HIV-1 clades C and E were strong transactivators of long terminal repeat (LTR) activity; Tat E also had a longer half-life than the other Tat proteins and interacted more efficiently with the stem-loop TAR element. Chimeric Tat proteins harboring the Tat E activation domain were strong transactivators of LTR expression. While Tat B, C, and E were able to rescue a Tat-defective HIV-1 proviral clone, Tat E was significantly more efficient at rescue than Tat C, possibly due to the relative stability of the Tat protein. Swapping the activation domains of Tat B, C, and E identified the cyclin T1 association domain as a critical determinant of the transactivation efficiency and of Tat-defective HIV-1 provirus rescue.
Mannose Binding Lectin Genotypes Influence Recovery from Hepatitis B Virus Infection
Authors: Thio Chloe L. , Mosbruger Timothy , Astemborski Jacquie , Greer Spencer , Kirk Gregory D. , O'Brien Stephen J. , Thomas David L.
Published: July 2005

Mannose binding lectin (MBL) is a central component of the innate immune response and thus may be important for determining hepatitis B virus (HBV) persistence. Since single-nucleotide polymorphisms (SNPs) in the gene encoding MBL (mbl2) alter the level of functional MBL, we hypothesized thatmbl2genotypes are a determinant of HBV persistence or recovery from viral infection. We tested this hypothesis by using a nested case control design with 189 persons with HBV persistence matched to 338 individuals who had naturally recovered from HBV infection. We determined genotypes of two promoter and three exon 1 SNPs inmbl2and grouped these genotypes according to the amount of functional MBL production. We found that the promoter SNP −221C, which leads to deficient MBL production, was more common in those subjects with viral persistence (odds ratio [OR], 1.38; 95% confidence interval [CI], 1.01 to 1.89;P= 0.04). Those subjects homozygous for the combination of promoter and exon 1 genotypes associated with the highest amount of functional MBL had significantly increased odds of recovery from infection (OR, 0.55; 95% CI, 0.37 to 0.84;P= 0.005). Conversely, those homozygous for the combination of promoter and exon 1 genotypes which produce the lowest amount of functional MBL were more likely to have viral persistence (OR, 1.76; 95% CI, 1.02 to 3.01;P= 0.04). These data are consistent with the hypothesis that functional MBL plays a central role in the pathogenesis of acute hepatitis B.
In Vitro Suppression of Human Immunodeficiency Virus Type 1 Replication by Measles Virus
Authors: García Mayra , Yu Xiao-Fang , Griffin Diane E. , Moss William J.
Published: July 2005

During the acute phase of measles, human immunodeficiency virus type 1 (HIV-1)-infected children have a transient, but dramatic, decrease in plasma HIV-1 RNA levels (W. J. Moss, J. J. Ryon, M. Monze, F. Cutts, T. C. Quinn, and D. E. Griffin, J. Infect. Dis.185:1035-1042, 2002). To determine the mechanism(s) by which coinfection with measles virus (MV) decreases HIV-1 replication, we established an in vitro culture system that reproduces this effect. The addition of MV to CCR5- or CXCR4-tropic HIV-1-infected human peripheral blood mononuclear cells (PBMCs) decreased HIV-1 p24 antigen production in a dose-dependent manner. This decrease occurred with the addition of MV before or after HIV-1. The inhibition of HIV-1 p24 antigen production was decreased when UV-inactivated MV or virus-free supernatant fluid from MV-infected PBMCs was used. Inhibition was not due to increased production of chemokines known to block coreceptor usage by HIV-1, a decrease in the percentage of CD4+T cells, or a decrease in chemokine receptor expression by CD4+T cells. Viability of PBMCs was decreased only 10 to 20% by MV coinfection; however, lymphocyte proliferation was decreased by 60 to 90% and correlated with decreased production of p24 antigen. These studies showed that an in vitro system of coinfected PBMCs could be used to dissect the mechanism(s) by which MV suppresses HIV-1 replication in coinfected children and suggest that inhibition of lymphocyte proliferation by MV may play a role in the suppression of HIV-1 p24 antigen production.
Propagation and Dissemination of Infection after Vaginal Transmission of Simian Immunodeficiency Virus
Authors: Miller Christopher J. , Li Qingsheng , Abel Kristina , Kim Eun-Young , Ma Zhong-Min , Wietgrefe Stephen , La Franco-Scheuch Lisa , Compton Lara , Duan Lijie , Shore Marta Dykhuizen , Zupancic Mary , Busch Marc , Carlis John , Wolinksy Steven , Haase Ashley T.
Published: July 2005

In the current global AIDS pandemic, more than half of new human immunodeficiency virus type 1 (HIV-1) infections are acquired by women through intravaginal HIV exposure. For this study, we explored pathogenesis issues relevant to the development of effective vaccines to prevent infection by this route, using an animal model in which female rhesus macaques were exposed intravaginally to a high dose of simian immunodeficiency virus (SIV). We examined in detail the events that transpire from hours to a few days after intravaginal SIV exposure through week 4 to provide a framework for understanding the propagation, dissemination, and establishment of infection in lymphatic tissues (LTs) during the acute stage of infection. We show that the mucosal barrier greatly limits the infection of cervicovaginal tissues, and thus the initial founder populations of infected cells are small. While there was evidence of rapid dissemination to distal sites, we also show that continuous seeding from an expanding source of production at the portal of entry is likely critical for the later establishment of a productive infection throughout the systemic LTs. The initially small founder populations and dependence on continuous seeding to establish a productive infection in systemic LTs define a small window of maximum vulnerability for the virus in which there is an opportunity for the host, vaccines, or other interventions to prevent or control infection.
CD8+T-Lymphocyte Response to Major Immunodominant Epitopes after Vaginal Exposure to Simian Immunodeficiency Virus: Too Late and Too Little
Authors: Reynolds Matthew R. , Rakasz Eva , Skinner Pamela J. , White Cara , Abel Kristina , Ma Zhong-Min , Compton Lara , Napoé Gnankang , Wilson Nancy , Miller Christopher J. , Haase Ashley , Watkins David I.
Published: July 2005

In the acute stage of infection following sexual transmission of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV), virus-specific CD8+T-lymphocyte responses partially control but do not eradicate infection from the lymphatic tissues (LTs) or prevent the particularly massive depletion of CD4+T lymphocytes in gut-associated lymphatic tissue (GALT). We explored hypothetical explanations for this failure to clear infection and prevent CD4+T-lymphocyte loss in the SIV/rhesus macaque model of intravaginal transmission. We examined the relationship between the timing and magnitude of the CD8+T-lymphocyte response to immunodominant SIV epitopes and viral replication, and we show first that the failure to contain infection is not because the female reproductive tract is a poor inductive site. We documented robust responses in cervicovaginal tissues and uterus, but only several days after the peak of virus production. Second, while we also documented a modest response in the draining genital and peripheral lymph nodes, the response at these sites also lagged behind peak virus production in these LT compartments. Third, we found that the response in GALT was surprisingly low or undetectable, possibly contributing to the severe and sustained depletion of CD4+T lymphocytes in the GALT. Thus, the virus-specific CD8+T-lymphocyte response is “too late and too little” to clear infection and prevent CD4+T-lymphocyte loss. However, the robust response in female reproductive tissues may be an encouraging sign that vaccines that rapidly induce high-frequency CD8+T-lymphocyte responses might be able to prevent acquisition of HIV-1 infection by the most common route of transmission.
Protease-Dependent Uncoating of a Complex Retrovirus
Authors: Lehmann-Che Jacqueline , Giron Marie-Lou , Delelis Olivier , Löchelt Martin , Bittoun Patricia , Tobaly-Tapiero Joelle , de Thé Hugues , Saïb Ali
Published: July 2005

Although retrovirus egress and budding have been partly unraveled, little is known about early stages of the replication cycle. In particular, retroviral uncoating, a process during which incoming retroviral cores are altered to allow the integration of the viral genome into host chromosomes, is poorly understood. To get insights into these early events of the retroviral cycle, we have used foamy complex retroviruses as a model. In this report, we show that a protease-defective foamy retrovirus is noninfectious, although it is still able to bud and enter target cells efficiently. Similarly, a retrovirus mutated in an essential viral protease-dependent cleavage site in the central part of Gag is noninfectious. Following entry, wild-type and mutant retroviruses are able to traffic along microtubules towards the microtubule-organizing center (MTOC). However, whereas nuclear import of Gag and of the viral genome was observed for the wild-type virus as early as 8 hours postinfection, incoming capsids and genome from mutant viruses remained at the MTOC. Interestingly, a specific viral protease-dependent Gag cleavage product was detected only for the wild-type retrovirus early after infection, demonstrating that cleavage of Gag by the viral protease at this stage of the virus life cycle is absolutely required for productive infection, an unprecedented observation among retroviruses.
Growth Suppression Induced by Downregulation of E6-AP Expression in Human Papillomavirus-Positive Cancer Cell Lines Depends on p53
Authors: Hengstermann Arnd , D'silva Michael A. , Kuballa Petric , Butz Karin , Hoppe-Seyler Felix , Scheffner Martin
Published: July 2005

The ubiquitin-protein ligase E6-AP is utilized by the E6 oncoprotein of human papillomaviruses (HPVs) associated with cervical cancer to target the tumor suppressor p53 for degradation. Here, we report that downregulation of E6-AP expression by RNA interference results in both the accumulation of p53 and growth suppression of the HPV-positive cervical cancer cell lines HeLa and SiHa. In addition, HeLa cells, in which p53 expression was suppressed by RNA interference, are significantly less sensitive to the downregulation of E6-AP expression with respect to growth suppression than parental HeLa cells. These data indicate that the anti-growth-suppressive properties of E6-AP in HPV-positive cells depend on its ability to induce p53 degradation.
Evidence of Recombination between Divergent Hepatitis E Viruses
Authors: van Cuyck Hélène , Fan Jun , Robertson David L. , Roques Pierre
Published: July 2005

Phylogenetic and recombination analysis was performed on 32 complete hepatitis E virus (HEV) genomes from infected humans and pigs. For the first time, evidence for recombination between divergent HEV strains was obtained, with at least two strains being found to have discordant phylogenetic relationships consistent with the occurrence of intragenotype recombination. This finding confirms that humans can be dually infected with divergent HEV strains and has implications for the emergence and evolution of new HEV epidemics.
Identification of TRAIL as an Interferon Regulatory Factor 3 Transcriptional Target
Authors: Kirshner Jessica R. , Karpova Alla Y. , Kops Maren , Howley Peter M.
Published: July 2005

Interferon production and apoptosis in virus-infected cells are necessary to prevent progeny virus production and to eliminate infected cells. Paramyxovirus infection induces apoptosis through interferon regulatory factor 3 (IRF-3), but the exact mechanism of how IRF-3 functions is unknown. We show that IRF-3 is involved in the transcriptional induction of TRAIL, a key player in the apoptosis pathway. IRF-3 upregulates TRAIL transcription following viral infection and binds an interferon-stimulated response element in the TRAIL promoter. The mRNA for TRAIL and its receptor, DR5, are induced following viral infection. These studies identify TRAIL as a novel IRF-3 transcriptional target.
Identification of Proteins Phosphorylated Directly by the Us3 Protein Kinase Encoded by Herpes Simplex Virus 1
Authors: Kato Akihisa , Yamamoto Mayuko , Ohno Takashi , Kodaira Hiroshi , Nishiyama Yukihiro , Kawaguchi Yasushi
Published: July 2005

We have developed a system to analyze the specific protein kinase activity of herpes simplex virus 1 Us3 in vitro and shown that Us3 directly phosphorylates viral proteins UL34, ICP22, and Us9 and the cellular protein Bad, previously reported to be putative substrates. Using this system, we determined the phosphorylation sites of UL34 and identified UL31 as a previously unreported, novel substrate of Us3. This system will be useful for further identification of Us3 substrates and their phosphorylation sites, clarification of the role of Us3 in viral replication, and identification of additional Us3 function(s).
Dissection of Gammaretroviral Receptor Function by Using Type III Phosphate Transporters as Models
Authors: Farrell Karen B. , Eiden Maribeth V.
Published: July 2005

Gammaretroviruses that enter cells via binding to a surface receptor use one of two fundamental mechanisms. In the first, binding of the virus particle to its cognate receptor is followed by fusion and internalization. The second, less common mechanism requires the addition of an accessory protein in order to achieve fusion and entry into the target cells; this protein is usually the soluble form of the envelope protein containing the receptor-binding domain (RBD). For some viruses, such as amphotropic murine leukemia virus (A-MLV), particles with fusion-defective envelope proteins can enter cells in the presence of their own RBD or that of another viral envelope, regardless of its cognate receptor, suggesting that these viruses share a common entry mechanism. A notable exception is gibbon ape leukemia virus (GALV). Fusion-impaired GALV envelope mutants can be
trans
-activated for infectivity only by GALV RBDs. Using dually functional GALV/A-MLV receptors, we examined the role of receptor with respect to which RBD could overcome fusion impaired virus entry.
Role of CXCR3 in the Immune Response to Murine Gammaherpesvirus 68
Authors: Lee Bong Joo , Giannoni Francesca , Lyon Ashley , Yada Shinichiro , Lu Bao , Gerard Craig , Sarawar Sally R.
Published: July 2005

The chemokine IP-10 (CXCL10) and its cellular receptor CXCR3 are upregulated in the lung during murine gammaherpesvirus 68 (MHV-68) infection. In order to determine the role of the CXCR3 chemokine receptor in the immune response to MHV-68, CXCR3
−/−
mice were infected with the virus. CXCR3
−/−
mice showed delayed clearance of replicating MHV-68 from the lungs. This correlated with delayed T-cell recruitment to the lungs and reduced cytolytic activity prior to viral clearance. Splenomegaly and the numbers of latently infected cells per spleen were transiently increased. Ηowever, CXCR3
−/−
mice showed normal virus-specific antibody titers and effective long-term control of MHV-68 infection.
Intrapatient Escape in the A*0201-Restricted Epitope SLYNTVATL Drives Evolution of Human Immunodeficiency Virus Type 1 at the Population Level
Authors: Edwards Charles T. T. , Pfafferott Katja J. , Goulder Philip J. R. , Phillips Rodney E. , Holmes Edward C.
Published: July 2005

The hypothesis that the intrapatient emergence of cytotoxic T-lymphocyte escape variants contributes to the evolution of human immunodeficiency virus type 1 at the population (interpatient) level was tested using the HLA-A*0201-restricted
gag p17
epitope SLYNTVATL. Using a simple experimental design, we investigated the evolutionary processes operating within this epitope among patients while compensating for the confounding influence of intrapatient natural selection. Using this approach, we revealed a pattern of A*0201-driven escape within patients, followed by the sustained transmission of these escape variants among patients irrespective of their HLA type.
Autonomy, consent, and limiting healthcare costs
Authors: Graber M A , Tansey J F
Published: July 2005

While protection of autonomy is crucial to the practice of medicine, there is the persistent risk of a disconnect between the notion of self-determination and the need for a socially responsible medical system. An example of unbridled autonomy is the preferential use of costly medications without an appreciation of the impact of using these more expensive drugs on the resource pool of others. In the USA, costly medications of questionable incremental benefit are frequently prescribed with the complicity of both doctors and patients. Limiting self-determination in medication choices via an appreciation of the principle of justice reaches a better moral balance, while at the same time acknowledging the goals of doing good and avoiding harm in patient care.
Newborn screening: new developments, new dilemmas
Authors: Kerruish N J , Robertson S P
Published: July 2005

Scientific and technological advances are lending pressure to expand the scope of newborn screening. Whereas this has great potential for improving child health, it also challenges our current perception of such programmes. Standard newborn screening programmes are clearly justified by the fact that early detection and treatment of affected individuals avoids significant morbidity and mortality. However, proposals to expand the scope and complexity of such testing are not all supported by a similar level of evidence for unequivocal benefit. We argue that screening for genetic susceptibility to complex disorders is inherently different from standard screening and, while of potential value, must be considered separately from conventional testing.
Stopping trials early for commercial reasons: the risk–benefit relationship as a moral compass: Table 1
Authors: Iltis A S
Published: July 2005

Decisions by industry sponsors to end clinical trials early for commercial reasons have been the subject of controversy. I argue that the principal consideration in assessing these decisions ought to be the way in which the termination would affect the trial’s risk–benefit relationship. If there is not yet sufficient benefit to be gained from the study to offset the risks to which participants were exposed and it is expected that important scientific information would be obtained if the trial were continued, early termination constitutes an unethical alteration of the risk−benefit relationship. This violates the grounds on which permission is given to conduct human research, patients consent to participate, and investigators agree to conduct studies. These knowable and avoidable changes in risk–benefit relationship shouldgenerallybe seen as impermissible.
Building on relationships of trust in biobank research
Authors: Hansson M G
Published: July 2005

Trust among current and future patients is essential for the success of biobank research. The submission of an informed consent is an act of trust by a patient or a research subject, but a strict application of the rule of informed consent may not be sensitive to the multiplicity of patient interests at stake, and could thus be detrimental to trust. According to a recently proposed law on “genetic integrity” in Sweden, third parties will be prohibited from requesting or seeking genetic information about an individual. Cumbersome restrictions on research may be lifted, thus creating a more favourable climate for medical research.
Justice and the NHS: a comment on Culyer
Authors: McLachlan H V
Published: July 2005

The nature and significance of equity and equality in relation to health and healthcare policy is discussed in the light of a recent article by Culyer. Culyer makes the following claims: (a) the importance of equity in relation to the provision of health care derives from the human need for health in order to flourish; and (b) for the sake of equity, equality of health among the members of particular political jurisdictions should be the aim of health policy. Both these claims are challenged in this paper.

The argument put forward is that it is only when needs arise and are met in particular contexts that need and equity are fused. The state and its agents and agencies should distribute what it distributes impartially, whatever it distributes. Whether or not equity applies to the distribution of healthcare services depends on how they are provided and not on their nature as “primary goods”. Contrary to what Culyer suggests, a policy of trying to produce the outcome of health equality would be inequitable. It would not be impartial and it would fail to treat persons as persons ought to be treated.
Does it matter that organ donors are not dead? Ethical and policy implications
Authors: Potts M , Evans D W
Published: July 2005

The “standard position” on organ donation is that the donor must be dead in order for vital organs to be removed, a position with which we agree. Recently, Robert Truog and Walter Robinson have argued that (1) brain death is not death, and (2) even though “brain dead” patients are not dead, it is morally acceptable to remove vital organs from those patients. We accept and defend their claim that brain death is not death, and we argue against both the US “whole brain” criterion and the UK “brain stem” criterion. Then we answer their arguments in favour of removing vital organs from “brain dead” and other classes of comatose patients. We dispute their claim that the removal of vital organs is morally equivalent to “letting nature take its course”, arguing that, unlike “allowing to die”, it is the removal of vital organs that kills the patient, not his or her disease or injury. Then, we argue that removing vital organs from living patients is immoral and contrary to the nature of medical practice. Finally, we offer practical suggestions for changing public policy on organ transplantation.
What is the role of the research ethics committee? Paternalism, inducements, and harm in research ethics
Authors: Garrard E , Dawson A
Published: July 2005

In a recent paper Edwards, Kirchin, and Huxtable have argued that research ethics committees (RECs) are often wrongfully paternalistic in their approach to medical research. They argue that it should be left to competent potential research subjects to make judgments about the acceptability of harms and benefits relating to research, and that this is not a legitimate role for any REC. They allow an exception to their overall antipaternalism, however, in that they think RECs should have the power to prohibit the use of financial inducements to recruit research subjects into trials. In this paper it is argued that these claims are unjustified and implausible. A sketch is provided of an alternative model of the role of the REC as an expert body making judgments about the acceptability of research proposals through a consensual weighing of different moral considerations.