bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis for a Limited Number of Gene Codons Can Predict Drug Resistance of
Mycobacterium tuberculosis
in a High-Incidence Community
Authors: Van Rie Annelies , Warren Robin , Mshanga Idris , Jordaan Annemarie M , van der Spuy Gian D. , Richardson Madalene , Simpson John , Gie Robert P. , Enarson Donald A. , Beyers Nulda , van Helden Paul D. , Victor Thomas C.
Published: July 2002

Correct and rapid diagnosis is essential in the management of multidrug-resistant tuberculosis (MDR-TB). In this population-based study of 61 patients with drug-resistant tuberculosis, we evaluated the frequency of mutations and compared the performance of genotypic (mutation analysis by dot blot hybridization) and phenotypic (indirect proportion method) drug resistance tests. Three selected codons (
rpoB531, rpoB526
, and
katG315
) allowed identification of 90% of MDR-TB cases. Ninety percent of rifampin, streptomycin, and ethambutol resistance and 75% of isoniazid resistance were detected by screening for six codons:
rpoB531, rpoB526, rrs-513, rpsL43, embB306
, and
katG315
. The performance (reproducibility, sensitivity, and specificity) of the genotypic method was superior to that of the routine phenotypic method, with the exception of sensitivity for isoniazid resistance. A commercialized molecular genetic test for a limited number of target loci might be a good alternative for a drug resistance screening test in the context of an MDR “DOTS-plus” strategy.
Rapid Detection of Mutations in the 23S rRNA Gene of
Helicobacter pylori
That Confers Resistance to Clarithromycin Treatment to the Bacterium
Authors: Matsumura Masayuki , Hikiba Yoko , Ogura Keiji , Togo Goichi , Tsukuda Izumi , Ushikawa Kenji , Shiratori Yasushi , Omata Masao
Published: July 2002

We developed a new method capable of detecting point mutations in the 23S rRNA gene of
Helicobacter pylori
using a LightCycler. Our method can detect a mutation in this gene in less than 1 h and can process many samples at once, thereby contributing to the selection of patients suitable for clarithromycin-based therapy.
Comparison of Three Nucleic Acid Amplification Assays of Cerebrospinal Fluid for Diagnosis of Cytomegalovirus Encephalitis
Authors: Bestetti Arabella , Pierotti Chiara , Terreni Mariarosa , Zappa Alessandra , Vago Luca , Lazzarin Adriano , Cinque Paola
Published: July 2002

The diagnostic reliabilities of three cytomegalovirus (CMV) nucleic acid amplification assays of cerebrospinal fluid (CSF) were compared by using CSF samples from human immunodeficiency virus-infected patients with a postmortem histopathological diagnosis of CMV encephalitis (
n
= 15) or other central nervous system conditions (
n
= 16). By using a nested PCR assay, the quantitative COBAS AMPLICOR CMV MONITOR PCR, and the NucliSens CMV pp67 nucleic acid sequence-based amplification assay, sensitivities were 93.3, 86.6, and 93.3%, respectively, and specificities were 93.7, 93.7, and 87.5%, respectively. The COBAS AMPLICOR assay revealed significantly higher CMV DNA levels in patients with diffuse ventriculoencephalitis than in patients with focal periventricular lesions.
Serological, Epidemiological, and Molecular Differences between Human T-Cell Lymphotropic Virus Type 1 (HTLV-1)-Seropositive Healthy Carriers and Persons with HTLV-I Gag Indeterminate Western Blot Patterns from the Caribbean
Authors: Rouet François , Meertens Laurent , Courouble Géry , Herrmann-Storck Cécile , Pabingui Raymond , Chancerel Bruno , Abid Adda , Strobel Michel , Mauclere Philippe , Gessain Antoine
Published: July 2002

To investigate the significance of serological human T-cell lymphotropic virus type 1 (HLTV-1) Gag indeterminate Western blot (WB) patterns in the Caribbean, a 6-year (1993 to 1998) cross-sectional study was conducted with 37,724 blood donors from Guadeloupe (French West Indies), whose sera were routinely screened by enzyme immunoassay (EIA) for the presence of HTLV-1 and -2 antibodies. By using stringent WB criteria, 77 donors (0.20%) were confirmed HTLV-1 seropositive, whereas 150 (0.40%;
P
< 0.001) were considered HTLV seroindeterminate. Among them, 41.3% (62) exhibited a typical HTLV-1 Gag indeterminate profile (HGIP). Furthermore 76 (50.7%) out of the 150 HTLV-seroindeterminate subjects were sequentially retested, with a mean duration of follow-up of 18.3 months (range, 1 to 70 months). Of these, 55 (72.4%) were still EIA positive and maintained the same WB profile whereas the others became EIA negative. This follow-up survey included 33 persons with an HGIP. Twenty-three of them (69.7%) had profiles that did not evolve over time. Moreover, no case of HTLV-1 seroconversion could be documented over time by studying such sequential samples. HTLV-1 seroprevalence was characterized by an age-dependent curve, a uniform excess in females, a significant relation with hepatitis B core (HBc) antibodies, and a microcluster distribution along the Atlantic coast of Guadeloupe. In contrast, the persons with an HGIP were significantly younger, had a 1:1 sex ratio, did not present any association with HBc antibodies, and were not clustered along the Atlantic façade. These divergent epidemiological features, together with discordant serological screening test results for subjects with HGIP and with the lack of HTLV-1 proviral sequences detected by PCR in their peripheral blood mononuclear cell DNA, strongly suggest that an HGIP does not reflect true HTLV-1 infection. In regard to these data, healthy blood donors with HGIP should be reassured that they are unlikely to be infected with HTLV-1 or HTLV-2.
Assessment of
Helicobacter pylori vacA
and
cagA
Genotypes and Host Serological Response
Authors: Figueiredo Céu , Quint Wim , Nouhan Nathalie , van den Munckhof Henk , Herbrink Paul , Scherpenisse Joost , de Boer Wink , Schneeberger Peter , Perez-Perez Guillermo , Blaser Martin J. , van Doorn Leen-Jan
Published: July 2002

Helicobacter pylori
strains can be distinguished by genotyping of virulence-associated genes, such as
vacA
and
cagA
. Because serological discrimination between strain types would reduce the need for endoscopy, 61 patients carrying
H. pylori
were studied by
vacA
and
cagA
genotyping of
H. pylori
in gastric biopsy specimens and by detection of specific serum antibodies. Serological responses to
H. pylori
were determined by Helicoblot (versions 2.0 and 2.1). Antibodies to CagA also were determined by a rapid anti-CagA assay (Pyloriset screen CagA) as well as by two noncommercially developed enzyme immunoassays, each using a recombinant CagA protein. Assessment of performance of the Helicoblot assays indicated substantial interobserver variation, with kappa values between 0.20 and 0.93. There was no relationship between the serological profiles on the Helicoblot and the genotypes from the same patients, except for strong associations between the presence of anti-CagA and the
cagA
-positive and
vacA
s1
H. pylori
genotypes. Detection of anti-CagA by the five different assays varied considerably, with kappa values ranging from 0.21 to 0.78. Using the
cagA
genotype as the “gold standard,” the sensitivity and specificity of the anti-CagA assays varied from 71.4 to 85.7% and from 54.2 to 100%, respectively. Thus, serological profiles of antibodies to
H. pylori
are heterogeneous and, with the exception of anti-CagA antibodies, show no relation to the
H. pylori vacA
and
cagA
genotypes. Detection of anti-CagA antibodies is strongly dependent on the test used.
Human Papillomavirus Type 16 E7 Oncoprotein Represses Transcription of Human Fibronectin
Authors: Rey Osvaldo , Lee Sora , Park No-Hee
Published: July 2002

The E7 oncoprotein encoded by human papillomavirus (HPV) type 16 repressed the transcription of fibronectin, a key component of the extracellular matrix. This repression, detected in several HPV-positive nontumorigenic and tumorigenic cell lines, was abolished when the Cys-X-X-Cys repeats in E7 were disrupted.
Cloning and Mutagenesis of the Murine Gammaherpesvirus 68 Genome as an Infectious Bacterial Artificial Chromosome
Authors: Adler Heiko , Messerle Martin , Wagner Markus , Koszinowski Ulrich H.
Published: July 2002

Gammaherpesviruses cause important infections of humans, in particular in immunocompromised patients. Recently, murine gammaherpesvirus 68 (MHV-68) infection of mice has been developed as a small animal model of gammaherpesvirus pathogenesis. Efficient generation of mutants of MHV-68 would significantly contribute to the understanding of viral gene functions in virus-host interaction, thereby further enhancing the potential of this model. To this end, we cloned the MHV-68 genome as a bacterial artificial chromosome (BAC) in
Escherichia coli
. During propagation in
E. coli
, spontaneous recombination events within the internal and terminal repeats of the cloned MHV-68 genome, affecting the copy number of the repeats, were occasionally observed. The gene for the green fluorescent protein was incorporated into the cloned BAC for identification of infected cells. BAC vector sequences were flanked by
loxP
sites to allow the excision of these sequences using recombinase Cre and to allow the generation of recombinant viruses with wild-type genome properties. Infectious virus was reconstituted from the BAC-cloned MHV-68. Growth of the BAC-derived virus in cell culture was indistinguishable from that of wild-type MHV-68. To assess the feasibility of mutagenesis of the cloned MHV-68 genome, a mutant virus with a deletion of open reading frame 4 was generated. Genetically modified MHV-68 can now be analyzed in functionally modified mouse strains to assess the role of gammaherpesvirus genes in virus-host interaction and pathogenesis.
The Human Cytomegalovirus IE86 Protein Can Block Cell Cycle Progression after Inducing Transition into the S Phase of Permissive Cells
Authors: Murphy Eain A. , Streblow Daniel N. , Nelson Jay A. , Stinski Mark F.
Published: July 2002

Human cytomegalovirus (HCMV) infection of permissive cells has been reported to induce a cell cycle halt. One or more viral proteins may be involved in halting progression at different stages of the cell cycle. We investigated how HCMV infection, and specifically IE86 protein expression, affects the cell cycles of permissive and nonpermissive cells. We used a recombinant virus that expresses the green fluorescent protein (GFP) to determine the effects of HCMV on the cell cycle of permissive cells. Fluorescence by GFP allowed us to select for only productively infected cells. Replication-defective adenovirus vectors expressing the IE72 or IE86 protein were also used to efficiently transduce 95% or more of the cells. The adenovirus-expressed IE86 protein was determined to be functional by demonstrating negative autoregulation of the major immediate-early promoter and activation of an early viral promoter in the context of the viral genome. To eliminate adenovirus protein effects, plasmids expressing GFP for fluorescent selection of only transfected cells and wild-type IE86 protein or a mutant IE86 protein were tested in permissive and nonpermissive cells. HCMV infection induced the entry of U373 cells into the S phase. All permissive cells infected with HCMV were blocked in cell cycle progression and could not divide. After either transduction or transfection and IE86 protein expression, the number of all permissive or nonpermissive cell types in the S phase increased significantly, but the cells could no longer divide. The IE72 protein did not have a significant effect on the S phase. Since IE86 protein inhibits cell cycle progression, the IE2 gene in a human fibroblast IE86 protein-expressing cell line was sequenced. The IE86 protein in these retrovirus-transduced cells has mutations in a critical region of the viral protein. The locations of the mutations and the function of the IE86 protein in controlling cell cycle progression are discussed.
Identification of an Export Control Sequence and a Requirement for the KH Domains in ICP27 from Herpes Simplex Virus Type 1
Authors: Soliman Tarik M. , Silverstein Saul J.
Published: July 2002

The herpes simplex virus type 1 (HSV-1) immediate-early protein ICP27 is an RNA-binding protein that performs multiple functions required for the expression of HSV-1 genes during a productive infection. One essential function involves shuttling between the nucleus and the cytoplasm. Some of the domains identified in ICP27 include a leucine-rich nuclear export sequence (NES), a nuclear localization signal, three KH-like RNA-binding domains, and an RGG-box type RNA-binding motif. To study the contribution of two of the essential domains in ICP27 to HSV gene expression, we generated recombinant herpesviruses carrying deleterious mutations in the NES and KH domains of ICP27. To accomplish this, we fused the green fluorescent protein (GFP) to ICP27 and utilized fluorescence as a marker to isolate recombinant herpesviruses. Fusion of GFP to wild-type ICP27 did not disturb its localization or function or significantly reduce virus yield. Analysis of HSV gene expression in cells infected with a recombinant virus carrying a point mutation in the first KH-like RNA-binding domain revealed that nuclear export of ICP27 was not blocked, and the expression of only a subset of ICP27-dependent late genes was affected. These findings suggest that individual KH-like RNA-binding motifs in ICP27 may be involved in binding distinct RNAs. Analysis of recombinant viruses carrying a lethal mutation in the NES of ICP27 was not accomplished because this mutation results in a strong dominant-negative phenotype. Finally, we demonstrate that shuttling by ICP27 is regulated by an export control sequence adjacent to its NES that functions like the inhibitory sequence element found adjacent to the NES of NS1 from influenza virus.
In Vivo Genomic Footprinting of the Human T-Cell Leukemia Virus Type 1 (HTLV-1) Long Terminal Repeat Enhancer Sequences in HTLV-1-Infected Human T-Cell Lines with Different Levels of Tax I Activity
Authors: Datta Shoibal , Kothari Nayantara H. , Fan Hung
Published: July 2002

The Tax protein of human T-cell leukemia virus type 1 (HTLV-1) enhances viral gene expression through sequences in the U3 region of the viral long terminal repeat. These sequences consist of three imperfect 21-bp repeats (TRE-1s) and a region between the promoter-central and promoter-proximal 21-bp repeats (TRE-2). The TRE-1s contain a core cyclic AMP response element (CRE) motif and can be bound by CREB, ATF-1, ATF-2, and other members of the CREB-ATF superfamily of transcription factors. Tax enhances CREB binding to TRE-1 in vitro, and it promotes dimerization of CREB as well as other bZIP proteins. Using ligation-mediated PCR on in vivo dimethyl sulfate-treated HTLV-1-infected cell lines MT-2 and MT-4, we have compiled a profile of protein occupancy in the HTLV-1 enhancer sequences in the presence of high (MT-2) and low (MT-4) levels of biologically active Tax I. The in vivo footprinting showed that all three TRE-1s were bound by protein(s), but only in MT-2 cells. In MT-2 cells, all TRE-1s showed strong protection of the G residues in the central CRE, and the footprints extended to differing degrees into the GC-rich flanking sequences. This indicated Tax I-dependent loading of transcription factors onto the HTLV-1 TRE-1s in vivo. In vivo footprinting on TRE-2 indicated that this region was bound by proteins regardless of the Tax I status of the cell line. However, the presence of Tax I increased the extent and altered the profile of proteins binding TRE-2 in vivo.
Sindbis-Group Alphavirus Replication in Periosteum and Endosteum of Long Bones in Adult Mice
Authors: Heise Mark T. , Simpson Dennis A. , Johnston Robert E.
Published: July 2002

Several alphaviruses, including the Sindbis-group viruses, Ross River virus, O'nyong-nyong virus, and Chikungunya virus, are associated with outbreaks of acute and persistent arthralgia and arthritis in humans. Mechanisms underlying alphavirus-induced arthralgia and arthritis are not clearly understood, though direct viral replication within or around the affected joints is thought to contribute to disease. S.A.AR86 is a Sindbis-group alphavirus closely related to the arthralgia-associated Ockelbo and GirdwoodS.A viruses. Following inoculation with S.A.AR86 derived from a molecular clone, infectious virus was isolated from bone and joint tissue 1 to 6 days postinfection. Studies using either in situ hybridization or S.A.AR86-derived double promoter viruses and replicons expressing green fluorescent protein localized sites of viral replication to the periosteum, tendons, and endosteum within the epiphyses of the long bones adjacent to articular joints. These results demonstrate that alphaviruses associated with arthralgia in humans replicate within bone-associated connective tissue adjacent to articular joints in an adult mouse model.
Cytoplasmic Domain Signal Sequences That Mediate Transport of Varicella-Zoster Virus gB from the Endoplasmic Reticulum to the Golgi
Authors: Heineman Thomas C. , Krudwig Nancy , Hall Susan L.
Published: July 2002

Normal herpesvirus assembly and egress depend on the correct intracellular localization of viral glycoproteins. While several post-Golgi transport motifs have been characterized within the cytoplasmic domains of various viral glycoproteins, few specific endoplasmic reticulum (ER)-to-Golgi transport signals have been described. We report the identification of two regions within the 125-amino-acid cytoplasmic domain of Varicella-Zoster virus gB that are required for its ER-to-Golgi transport. Native gB or gB containing deletions and specific point mutations in its cytoplasmic domain was expressed in mammalian cells. ER-to-Golgi transport of gB was assessed by indirect immunofluorescence and by the acquisition of Golgi-dependent posttranslational modifications. These studies revealed that the ER-to-Golgi transport of gB requires a nine-amino-acid region (YMTLVSAAE) within its cytoplasmic domain. Mutations of individual amino acids within this region markedly impaired the transport of gB from the ER to the Golgi, indicating that this domain functions by a sequence-dependent mechanism. Deletion of the C-terminal 17 amino acids of the gB cytoplasmic domain was also shown to impair the transport of gB from the ER to the Golgi. However, internal mutations within this region did not disrupt the transport of gB, indicating that its function during gB transport is not sequence dependent. Native gB is also transported to the nuclear membrane of transfected cells. gB lacking as many as 67 amino acids from the C terminus of its cytoplasmic domain continued to be transported to the nuclear membrane at apparently normal levels, indicating that the cytoplasmic domain of gB is not required for nuclear membrane localization.
Canine Adenovirus Type 2 Attachment and Internalization: Coxsackievirus-Adenovirus Receptor, Alternative Receptors, and an RGD-Independent Pathway
Authors: Soudais Claire , Boutin Sylvie , Hong Saw See , Chillon Miguel , Danos Olivier , Bergelson Jeffrey M. , Boulanger Pierre , Kremer Eric J.
Published: July 2002

The best-characterized receptors for adenoviruses (Ads) are the coxsackievirus-Ad receptor (CAR) and integrins αvβ5and αvβ3, which facilitate entry. The αvintegrins recognize an Arg-Gly-Asp (RGD) motif found in some extracellular matrix proteins and in the penton base in most human Ads. Using a canine adenovirus type 2 (CAV-2) vector, we found that CHO cells that express CAR but not wild-type CHO cells are susceptible to CAV-2 transduction. Cells expressing αMβ2integrins or major histocompatibility complex class I (MHC-I) molecules but which do not express CAR were not transduced. Binding assays showed that CAV-2 attaches to a recombinant soluble form of CAR and that Ad type 5 (Ad5) fiber, penton base, and an anti-CAR antibody partially blocked attachment. Using fluorescently labeled CAV-2 particles, we found that in some cells nonpermissive for transduction, inhibition was at the point of internalization and not attachment. The transduction efficiency of CAV-2, which lacks an RGD motif, surprisingly mimicked that of Ad5 when tested in cells selectively expressing αvβ5and αvβ3integrins. Our results demonstrate that CAV-2 transduction is augmented by CAR and possibly by αvβ5, though transduction can be CAR and αvβ3/5independent but is αMβ2, MHC-I, and RGD independent, demonstrating a transduction mechanism which is distinct from that of Ad2/5.
Life Cycle of an Endogenous Retrovirus,
ZAM
, in
Drosophila melanogaster
Authors: Leblanc P. , Desset S. , Giorgi F. , Taddei A. R. , Fausto A. M. , Mazzini M. , Dastugue B. , Vaury C.
Published: July 2002

ZAM
is an
env
-containing member of the
gypsy
family of retrotransposons that represents a possible retrovirus of invertebrates. In this paper, we traced
ZAM
mobilization to get information about a potential path a retroelement may take to reach the germ line of its host. In situ hybridization on whole-mount tissues and immunocytochemistry analyses with antibodies raised against
ZAM
Gag and Env proteins have shown that all components necessary to assemble
ZAM
viral particles, i.e.,
ZAM
full-length RNAs and Gag and Env polypeptides, are coexpressed in a small set of follicle cells surrounding the oocyte. By electron microscopy, we have shown that
ZAM
viral particles are indeed detected in this somatic lineage of cells, which they leave and enter the closely apposed oocyte. Our data provide evidence that the vesicular traffic and yolk granules in the process of vitellogenesis play an important role in
ZAM
transfer to the oocyte. Our data support the possibility that vitellogenin transfer to the oocyte may help a retroelement pass to the germ line with no need of its envelope product.
Characterization of Transcripts Expressed from Human Herpesvirus 6A Strain GS Immediate-Early Region B U16-U17 Open Reading Frames
Authors: Flebbe-Rehwaldt Linda M. , Wood Charles , Chandran Bala
Published: July 2002

Several gene fragments of human herpesvirus 6 (HHV-6) have been shown to activate the human immunodeficiency virus (HIV) type 1 long terminal repeat (LTR). An open reading frame (ORF) designated B701 (Y. Geng, B. Chandran, S. F. Josephs, and C. Wood, J. Virol. 66:1564–1570, 1992), found within a 22-kb HHV-6A strain GS [HHV-6A(GS)] genomic fragment and a 3.8-kb
Sal
I subfragment, was shown to activate the HIV LTR. B701, also known as HHV-6 U16, is located in the immediate-early B (IE-B) region of the genome. The sequence of the 3.8-kb genomic fragment of HHV-6A(GS) is nearly identical to the published sequence of HHV-6A strain U1102, with minor differences. The HHV-6A(GS) B701 ORF (U16) was used to screen an HHV-6A(GS) cDNA library, and two different but overlapping cDNAs were identified. These cDNAs represent differently spliced transcripts ending at different polyadenylation signals. The ORFs included in the cDNAs are positionally homologous to the human cytomegalovirus (HCMV) UL36 ORF. The ORF in one cDNA was generated by splicing together in frame ORFs U17 and U16, and the second cDNA included ORFs U16 and U15. A third differentially spliced cDNA (U16+), was identified by 5′ rapid amplification of cDNA ends. The predicted protein was identical to the U16 portion of the U17/U16 spliced gene product but did not include the U17 portion. 5′-extension analyses of the mRNAs demonstrated that at least two potential transcription initiation sites were used to express the transcripts encoding U17 and U16 gene products. Single-stranded U16 and U17 gene-specific RNA probes hybridized with at least five RNA species from infected cells and demonstrated that the expression of these transcripts was differentially regulated. The U17/U16 spliced gene products were expressed at IE times after infection, but a multiply spliced gene product encoded by U16 was expressed as a late gene. The U17/U16 and the U16+ gene products transactivated the HIV LTR. Thus, while there are similarities to the HCMV UL36-UL38 gene family, some of the IE-B U17/U16 transcripts are unique to HHV-6.
Mutational Analysis of Conserved Domains within the Cytoplasmic Tail of gp41 from Human Immunodeficiency Virus Type 1: Effects on Glycoprotein Incorporation and Infectivity
Authors: Piller Sabine C. , Dubay John W. , Derdeyn Cynthia A. , Hunter Eric
Published: July 2002

The transmembrane (TM) glycoprotein gp41 of human immunodeficiency virus type 1 possesses an unusually long (∼150 amino acids) and highly conserved cytoplasmic region. Previous studies in which this cytoplasmic tail had been deleted partially or entirely have suggested that it is important for virus infectivity and incorporation of the gp120-gp41 glycoprotein complex into virions. To determine which regions of the conserved C-terminal domains are important for glycoprotein incorporation and infectivity, several small deletions and amino acid substitutions which modify highly conserved motifs were constructed in the infectious proviral background of NL4.3. The effects of these mutations on infectivity and glycoprotein incorporation into virions produced from transfected 293-T cells and infected H9 and CEM×174 cells were determined. With the exception of a mutation deleting amino acids QGL, all of the constructs resulted in decreased infectivity of the progeny virus both in a single-round infectivity assay and in a multiple-infection assay in H9 and CEM×174 cells. For most mutations, the decreased infectivity was correlated with a decreased incorporation of glycoprotein into virions. Substitution of the arginines (residues 839 and 846) with glutamates also reduced infectivity, but without a noticeable decrease in the amount of glycoprotein incorporated into virus produced from infected T cells. These results demonstrate that minor alterations in the conserved C-terminal region of the gp41 cytoplasmic tail can result in reductions in infectivity that correlate for most but not all constructs with a decrease in glycoprotein incorporation. Observed cell-dependent differences suggest the involvement of cellular factors in regulating glycoprotein incorporation and infectivity.
Abundant Defective Viral Particles Budding from Microglia in the Course of Retroviral Spongiform Encephalopathy
Authors: Hansen Regine , Czub Stefanie , Werder Evi , Herold Jens , Gosztonyi Georg , Gelderblom Hans , Schimmer Simone , Mazgareanu Stefan , ter Meulen Volker , Czub Markus
Published: July 2002

A pathogenetic hallmark of retroviral neurodegeneration is the affinity of neurovirulent retroviruses for microglia cells, while degenerating neurons are excluded from retroviral infections. Microglia isolated ex vivo from rats peripherally infected with a neurovirulent retrovirus released abundant mature type C virions; however, infectivity associated with microglia was very low. In microglia, viral transcription was unaffected but envelope proteins were insufficiently cleaved into mature viral proteins and were not detected on the microglia cell surface. These microglia-specific defects in envelope protein translocation and processing not only may have prevented formation of infectious virus particles but also may have caused further cellular defects in microglia with the consequence of indirect neuronal damage. It is conceivable that similar events play a role in neuro-AIDS.
An Envelope Glycoprotein of the Human Endogenous Retrovirus HERV-W Is Expressed in the Human Placenta and Fuses Cells Expressing the Type D Mammalian Retrovirus Receptor
Authors: Blond Jean-Luc , Lavillette Dimitri , Cheynet Valérie , Bouton Olivier , Oriol Guy , Chapel-Fernandes Sylvie , Mandrand Bernard , Mallet François , Cosset François-Loïc
Published: July 2002

A new human endogenous retrovirus (HERV) family, termed HERV-W, was recently described (J.-L. Blond, F. Besème, L. Duret, O. Bouton, F. Bedin, H. Perron, B. Mandrand, and F. Mallet, J. Virol. 73:1175–1185, 1999). HERV-W mRNAs were found to be specifically expressed in placenta cells, and an
env
cDNA containing a complete open reading frame was recovered. In cell-cell fusion assays, we demonstrate here that the product of the HERV-W
env
gene is a highly fusogenic membrane glycoprotein. Transfection of an HERV-W Env expression vector in a panel of cell lines derived from different species resulted in formation of syncytia in primate and pig cells upon interaction with the type D mammalian retrovirus receptor. Moreover, envelope glycoproteins encoded by HERV-W were specifically detected in placenta cells, suggesting that they may play a physiological role during pregnancy and placenta formation.
Rta of Murine Gammaherpesvirus 68 Reactivates the Complete Lytic Cycle from Latency
Authors: Wu Ting-Ting , Usherwood Edward J. , Stewart James P. , Nash Anthony A. , Sun Ren
Published: July 2002

Herpesviruses are characterized as having two distinct life cycle phases: lytic replication and latency. The mechanisms of latency establishment and maintenance, as well as the switch from latency to lytic replication, are poorly understood. Human gammaherpesviruses, including Epstein-Barr virus (EBV) and human herpesvirus-8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), are associated with lymphoproliferative diseases and several human tumors. Unfortunately, the lack of cell lines to support efficient de novo productive infection and restricted host ranges of EBV and HHV-8 make it difficult to explore certain important biological questions. Murine gammaherpesvirus 68 (MHV-68, or γHV68) can establish de novo lytic infection in a variety of cell lines and is also able to infect laboratory mice, offering an ideal model with which to study various aspects of gammaherpesvirus infection. Here we describe in vitro studies of the mechanisms of the switch from latency to lytic replication of MHV-68. An MHV-68 gene,
rta
(replication and transcription activator), encoded primarily by open reading frame 50 (ORF50), is homologous to the
rta
genes of other gammaherpesviruses, including HHV-8 and EBV. HHV-8 and EBV Rta have been shown to play central roles in viral reactivation from latency. We first studied the kinetics of MHV-68
rta
gene transcription during de novo lytic infection. MHV-68
rta
was predominantly expressed as a 2-kb immediate-early transcript. Sequence analysis of MHV-68
rta
cDNA revealed that an 866-nucleotide intron 5′ of ORF50 was removed to create the Rta ORF of 583 amino acids. To test the functions of MHV-68 Rta in reactivation, a plasmid expressing Rta was transfected into a latently infected cell line, S11E, which was established from a B-cell lymphoma in an MHV-68-infected mouse. Rta induced expression of viral early and late genes, lytic replication of viral DNA, and production of infectious viral particles. We conclude that Rta alone is able to disrupt latency, activate viral lytic replication, and drive the lytic cycle to completion. This study indicates that MHV-68 provides a valuable model for investigating regulation of the balance between latency and lytic replication in vitro and in vivo.
Recombinant Bovine/Human Parainfluenza Virus Type 3 (B/HPIV3) Expressing the Respiratory Syncytial Virus (RSV) G and F Proteins Can Be Used To Achieve Simultaneous Mucosal Immunization against RSV and HPIV3
Authors: Schmidt Alexander C. , McAuliffe Josephine M. , Murphy Brian R. , Collins Peter L.
Published: July 2002

Recombinant bovine/human parainfluenza virus type 3 (rB/HPIV3), a recombinant bovine PIV3 (rBPIV3) in which the F and HN genes were replaced with their HPIV3 counterparts, was used to express the major protective antigens of respiratory syncytial virus (RSV) in order to create a bivalent mucosal vaccine against RSV and HPIV3. The attenuation of rB/HPIV3 is provided by the host range restriction of the BPIV3 backbone in primates. RSV G and F open reading frames (ORFs) were placed under the control of PIV3 transcription signals and inserted individually into the rB/HPIV3 genome in the promoter-proximal position preceding the nucleocapsid protein gene. The recombinant PIV3 expressing the RSV G ORF (rB/HPIV3-G1) was not restricted in its replication in vitro, whereas the virus expressing the RSV F ORF (rB/HPIV3-F1) was eightfold restricted compared to its rB/HPIV3 parent. Both viruses replicated efficiently in the respiratory tract of hamsters, and each induced RSV serum antibody titers similar to those induced by RSV infection and anti-HPIV3 titers similar to those induced by HPIV3 infection. Immunization of hamsters with rB/HPIV3-G1, rB/HPIV3-F1, or a combination of both viruses resulted in a high level of resistance to challenge with RSV or HPIV3 28 days later. These results describe a vaccine strategy that obviates the technical challenges associated with a live attenuated RSV vaccine, providing, against the two leading viral agents of pediatric respiratory tract disease, a bivalent vaccine whose attenuation phenotype is based on the extensive host range sequence differences of BPIV3.
“Stealth” Adenoviruses Blunt Cell-Mediated and Humoral Immune Responses against the Virus and Allow for Significant Gene Expression upon Readministration in the Lung
Authors: Croyle Maria A. , Chirmule Narendra , Zhang Yi , Wilson James M.
Published: July 2002

Most of the early gene therapy trials for cystic fibrosis have been with adenovirus vectors. First-generation viruses with E1a and E1b deleted are limited by transient expression of the transgene and substantial inflammatory responses. Gene transfer is also significantly curtailed following a second dose of virus. In an effort to reduce adenovirus-associated inflammation, capsids of first-generation vectors were modified with various activated monomethoxypolyethylene glycols. Cytotoxic T-lymphocyte production was significantly reduced in C57BL/6 mice after a single intratracheal administration of modified vectors, and length of gene expression was extended from 4 to 42 days. T-cell subsets from mice exposed to the conjugated vectors demonstrated a marked decrease in Th1 responses and slight enhancement of Th2 responses compared to animals dosed with native virus. Neutralizing antibodies (NAB) against adenovirus capsid proteins were reduced in serum and bronchoalveolar lavage fluid of animals after a single dose of modified virus, allowing significant levels of gene expression upon rechallenge with native adenovirus. Modification with polyethylene glycol (PEG) also allowed substantial gene expression from the new vectors in animals previously immunized with unmodified virus. However, gene expression was significantly reduced after two doses of the same PEG-conjugated vector. Alternating the activation group of PEG between doses did produce significant gene expression upon readministration. This technology in combination with second-generation or helper-dependent adenovirus could produce dosing strategies which promote successful readministration of vector in clinical trials and marked expression in patients with significant anti-adenovirus NAB levels and reduce the possibility of immune reactions against viral vectors for gene therapy.
A Herpes Simplex Virus Type 1 γ34.5 Second-Site Suppressor Mutant That Exhibits Enhanced Growth in Cultured Glioblastoma Cells Is Severely Attenuated in Animals
Authors: Mohr Ian , Sternberg David , Ward Stephen , Leib David , Mulvey Matthew , Gluzman Yakov
Published: July 2002

We describe here the neurovirulence properties of a herpes simplex virus type 1 γ34.5 second-site suppressor mutant. γ34.5 mutants are nonneurovirulent in animals and fail to grow in a variety of cultured cells due to a block at the level of protein synthesis. Extragenic suppressors with restored capacity to replicate in cells that normally do not support the growth of the parental γ34.5 deletion mutant have been isolated. Although the suppressor virus reacquires the ability to grow in nonpermissive cultured cells, it remains severely attenuated in mice and is indistinguishable from the mutant γ34.5 parent virus at the doses investigated. Repairing the γ34.5 mutation in the suppressor mutant restores neurovirulence to wild-type levels. These studies illustrate that (i) the protein synthesis and neurovirulence defects observed in γ34.5 mutant viruses can be genetically separated by an extragenic mutation at another site in the viral chromosome; (ii) the extragenic suppressor mutation does not affect neurovirulence; and (iii) the attenuated γ34.5 mutant, which replicates poorly in many cell types, can be modified by genetic selection to generate a nonpathogenic variant that regains the ability to grow robustly in a nonpermissive glioblastoma cell line. As this γ34.5 second-site suppressor variant is attenuated and replicates vigorously in neoplastic cells, it may have potential as a replication-competent, viral antitumor agent.
DNA Replication Efficiency Depends on Transcription Factor-Binding Sites
Authors: Turner William J. , Woodworth Mary E.
Published: July 2002

Naturally arising variants of simian virus 40 (SV40), generated by serial passage of the virus at high multiplicities of infection, provide important insight into the role of transcription factor-binding sites in enhancing DNA replication. Although the variants that arise from numerous recombination events are the result of selective pressure to replicate more efficiently than the other variants in the infection, there is no transcription pressure. Therefore, it is interesting that a minimum of two viral Sp1 transcription factor-binding sites are retained and that host AP-1 and NF-1 transcription factor-binding sites are incorporated into the 100-bp regulatory region that maximizes DNA replication in these variants. We cotransfected COS-1 cells (that provide viral large T antigen for DNA replication) to examine the effect of transcription factor-binding sites on the replication of plasmid constructs that contain the SV40 origin of replication (
ori
). The level of relative replication efficiency (RRE) depends on the number and type of transcription factor-binding sites. Replication increases as the number of transcription factor-binding sites increases within the regulatory region of the variants; AP-1 sites are more effective than NF-1 transcription factor-binding sites. Competition between constructs in transfections magnifies the difference in their RREs. The results indicate that transcription factor-binding sites play an important role in enhancing DNA replication.
Identification of a Novel Transcriptional Repressor Encoded by Human Cytomegalovirus
Authors: LaPierre Lorie A. , Biegalke Bonita J.
Published: July 2002

The expression of human cytomegalovirus (HCMV) genes during viral replication is precisely regulated, with the interactions of both transcriptional activators and repressors determining the level of gene expression. One gene of HCMV, the US3 gene, is transcriptionally repressed early in infection. Repression of US3 expression requires viral infection and protein synthesis and is mediated through a DNA sequence, the transcriptional repressive element. In this report, we identify the protein that represses US3 transcription as the product of the HCMV UL34 open reading frame. The protein encoded by UL34 (pUL34) binds to the US3 transcriptional repressive element in yeast and in vitro. pUL34 localizes to the nucleus and alone is sufficient for repression of US3 expression. The data presented here, along with earlier data (B. J. Biegalke, J. Virol. 72:5457–5463, 1998), suggests that pUL34 binding of the transcriptional repressive element prevents transcription initiation complex formation.
Free Major Histocompatibility Complex Class I Heavy Chain Is Preferentially Targeted for Degradation by Human T-Cell Leukemia/Lymphotropic Virus Type 1 p12IProtein
Authors: Johnson Julie M. , Nicot Christophe , Fullen Jake , Ciminale Vincenzo , Casareto Luca , Mulloy James C. , Jacobson Steve , Franchini Genoveffa
Published: July 2002

Human T-cell leukemia virus type 1 (HTLV-1) establishes a persistent infection in the host despite a vigorous virus-specific immune response. Here we demonstrate that an HTLV-1-encoded protein, p12I, resides in the endoplasmic reticulum (ER) and Golgi and physically binds to the free human major histocompatibility complex class I heavy chains (MHC-I-Hc) encoded by the HLA-A2, -B7, and -Cw4 alleles. As a result of this interaction, the newly synthesized MHC-I-Hc fails to associate with β2-microglobulin and is retrotranslocated to the cytosol, where it is degraded by the proteasome complex. Targeting of the free MHC-I-Hc, and not the MHC-I-Hc–β2-microglobulin complex, by p12Irepresents a novel mechanism of viral interference and disrupts the intracellular trafficking of MHC-I, which results in a significant decrease in surface levels of MHC-I on human T-cells. These findings suggest that the interaction of p12Iwith MHC-1-Hc may interfere with antigen presentation in vivo and facilitate escape of HTLV-1-infected cells from immune recognition.
Efficacy of Dideoxynucleosides against Human Foamy Virus and Relationship to Its Reverse Transcriptase Amino Acid Sequence and Structure
Authors: Yvon-Groussin Anne , Mugnier Pierre , Bertin Philippe , Grandadam Marc , Agut Henri , Huraux Jean Marie , Calvez Vincent
Published: July 2002

Human foamy virus (HFV), a retrovirus of simian origin which occasionally infects humans, is the basis of retroviral vectors in development for gene therapy. Clinical considerations of how to treat patients developing an uncontrolled infection by either HFV or HFV-based vectors need to be raised. We determined the susceptibility of the HFV to dideoxynucleosides and found that only zidovudine was equally efficient against the replication of human immunodeficiency virus type 1 (HIV-1) and HFV. By contrast, zalcitabine (ddC), lamivudine (3TC), stavudine (d4T), and didanosine (ddI) were 3-, 3-, 30-, and 46-fold less efficient against HFV than against HIV-1, respectively. Some amino acid residues known to be involved in HIV-1 resistance to ddC, 3TC, d4T, and ddI were found at homologous positions of HFV reverse transcriptase (RT). These critical amino acids are located at the same positions in the three-dimensional structure of HIV-1 and HFV RT, suggesting that both enzymes share common patterns of inhibition.
Protection against Simian Immunodeficiency Virus Vaginal Challenge by Using Sabin Poliovirus Vectors
Authors: Crotty Shane , Miller Christopher J. , Lohman Barbara L. , Neagu Martha R. , Compton Lara , Lu Ding , Lü Fabien X.-S. , Fritts Linda , Lifson Jeffrey D. , Andino Raul
Published: July 2002

Here we provide the first report of protection against a vaginal challenge with a highly virulent simian immunodeficiency virus (SIV) by using a vaccine vector. New poliovirus vectors based on Sabin 1 and 2 vaccine strain viruses were constructed, and these vectors were used to generate a series of new viruses containing SIVgag,pol,env,nef, andtatin overlapping fragments. Two cocktails of 20 transgenic polioviruses (SabRV1-SIV and SabRV2-SIV) were inoculated into seven cynomolgus macaques. All monkeys produced substantial anti-SIV serum and mucosal antibody responses. SIV-specific cytotoxic T-lymphocyte responses were detected in three of seven monkeys after vaccination. All 7 vaccinated macaques, as well as 12 control macaques, were challenged vaginally with pathogenic SIVmac251. Strikingly, four of the seven vaccinated animals exhibited substantial protection against the vaginal SIV challenge. All 12 control monkeys became SIV positive. In two of the seven SabRV-SIV-vaccinated monkeys we found no virological evidence of infection following challenge, indicating that these two monkeys were completely protected. Two additional SabRV-SIV-vaccinated monkeys exhibited a pronounced reduction in postacute viremia to <103copies/ml, suggesting that the vaccine elicited an effective cellular immune response. Three of six control animals developed clinical AIDS by 48 weeks postchallenge. In contrast, all seven vaccinated monkeys remained healthy as judged by all clinical parameters. These results demonstrate the efficacy of SabRV as a potential human vaccine vector, and they show that the use of a vaccine vector cocktail expressing an array of defined antigenic sequences can be an effective vaccination strategy in an outbred population.
Antibody-Directed Targeting of Retroviral Vectors via Cell Surface Antigens
Authors: Morizono Kouki , Bristol Gregory , Xie Yi-ming , Kung Sam Kam-Pun , Chen Irvin S. Y.
Published: July 2002

Targeted stable transduction of specific cells is a highly desirable goal for gene therapy applications. We report an efficient and broadly applicable approach for targeting retroviral vectors to specific cells. We find that the envelope of the alphavirus Sindbis virus can pseudotype human immunodeficiency virus type 1- and murine leukemia virus-based retroviral vectors. When modified to contain the Fc-binding domain of protein A, this envelope gives a significant enhancement in specificity in combination with antibodies specific for HLA and CD4 relative to that without antibody. Unlike previous targeting strategies for retroviral transduction, the virus titers are relatively high and stable and can be further increased by ultracentrifugation. This study provides proof of principle for a targeting strategy that would be generally useful for many gene therapy applications.
A Preponderance of CCR5+CXCR4+Mononuclear Cells Enhances Gastrointestinal Mucosal Susceptibility to Human Immunodeficiency Virus Type 1 Infection
Authors: Poles Michael A. , Elliott Julie , Taing Philip , Anton Peter A. , Chen Irvin S. Y.
Published: July 2002

The gastrointestinal mucosa harbors the majority of the body's CD4+cells and appears to be uniquely susceptible to human immunodeficiency virus type 1 (HIV-1) infection. We undertook this study to examine the role of differences in chemokine receptor expression on infection of mucosal mononuclear cells (MMCs) and peripheral blood mononuclear cells (PBMCs) by R5- and X4-tropic HIV-1. We performed in vitro infections of MMCs and PBMCs with R5- and X4-tropic HIV-1, engineered to express murine CD24 on the infected cell's surface, allowing for quantification of HIV-infected cells and their phenotypic characterization. A greater percentage of MMCs than PBMCs are infected by both R5- and X4-tropic HIV-1. Significant differences exist in terms of chemokine receptor expression in the blood and gastrointestinal mucosa; mucosal cells are predominantly CCR5+CXCR4+, while these cells make up less than 20% of the peripheral blood cells. It is this cell population that is most susceptible to infection with both R5- and X4-tropic HIV-1 in both compartments. Regardless of whether viral isolates were derived from the blood or mucosa of HIV-1-infected patients, HIV-1 p24 production was greater in MMCs than in PBMCs. Further, the chemokine receptor tropism of these patient-derived viral isolates did not differ between compartments. We conclude that, based on these findings, the gastrointestinal mucosa represents a favored target for HIV-1, in part due to its large population of CXCR4+CCR5+target cells and not to differences in the virus that it contains.