bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Digene Hybrid Capture 2 and Conventional Culture for Detection of
Chlamydia trachomatis
and
Neisseria gonorrhoeae
in Cervical Specimens
Authors: Darwin Ling H. , Cullen Allison P. , Arthur Patrick M. , Long Carole D. , Smith Kim R. , Girdner Jennifer L. , Hook Edward W. , Quinn Thomas C. , Lorincz Attila T.
Published: July 2002

Digene's Hybrid Capture 2 (HC2) CT/GC, CT-ID, and GC-ID DNA tests were evaluated by comparison to traditional culture methods for detecting
Chlamydia trachomatis
and
Neisseria gonorrhoeae
infections in 669 cervical specimens from high-risk female populations attending two sexually transmitted disease clinics. For detection of either or both infections, the HC2 CT/GC test algorithm had 93.8% sensitivity and 95.9% specificity compared to those of culture. After resolution of discrepant results by direct fluorescent-antibody (DFA) staining or PCR assay, the relative sensitivity and specificity of the HC2 CT/GC test algorithm increased to 94.8 and 99.8%, while the values for culture were 83.6% (McNemar's
P
value, 0.0062) and 100%, respectively. For detection of the individual pathogens, the relative sensitivities for the HC2 CT-ID and GC-ID tests were 97.2 and 92.2% and the specificities were greater than 99% compared to culture adjucated by DFA staining and PCR. Test performance varied at the two clinics: the HC2 CT/GC algorithm, CT-ID, and GC-ID tests had significantly higher sensitivities (McNemar's
P
value, <0.05) than that of culture for the population at one clinic as well as for the combined populations. At the other clinic, the HC2 tests performed as well as culture.
Genetic Variation of Capsid Protein VP7 in Genotype G4 Human Rotavirus Strains: Simultaneous Emergence and Spread of Different Lineages in Argentina
Authors: Bok Karin , Matson David O. , Gomez Jorge A.
Published: July 2002

Rotavirus is the most-common cause of severe diarrhea in young children. Complete rotavirus characterization includes determination of the antigenic type of the two outer capsid proteins, VP7 and VP4, designated G and P types, respectively. During a nationwide rotavirus surveillance study, genotype G4 frequency increased during the second year. To evaluate further the mechanism of emergence and the relationship among G4 strains, the genetic diversity of VP7 capsid protein in these samples was studied in detail. Overall nucleotide sequence divergence ranged from less than 0.1 to 19.5%, a higher divergence than that observed for other rotavirus G types (0.1 to 9%). Sequences were classified into two major lineages (designated I and II) based on their nucleotide distances. The most heterogeneous lineage was further subdivided into four sublineages (designated Ia to Id). Most Argentine sequences were of sublineages Ib and Ic, which were confirmed to be independent sequence clusters by parsimony analysis. This study describes different lineages and sublineages within G4 strains and shows that Argentine strains are distantly related to reference strain ST3. The appearance of at least two G4 genotype (sub)lineages during 1998 demonstrates that the increased frequency of these strains was due to the synchronized emergence of different groups of strains.
Transdominant Activity of Human Immunodeficiency Virus Type 1 Vpr with a Mutation at Residue R73
Authors: Sawaya Bassel E. , Khalili Kamel , Gordon Jennifer , Srinivasan Alagarsamy , Richardson Max , Rappaport Jay , Amini Shohreh
Published: July 2002

The 96-amino-acid-long human immunodeficiency virus type 1 virion-encoded accessory protein Vpr is of particular interest, as this protein, which is found in association with viral particles, can exert a regulatory effect on both virus replication and host cell function. Evidently, Vpr, through interaction with several host regulatory proteins, can modulate transcription from the viral long terminal repeat promoter. Expression of Vpr in cells results in deregulation of cell proliferation during the cell cycle pathway at the G
2
stage. Vpr has unique structural features consisting of multiple functional domains. In this study, we have focused on the leucine/isoleucine-rich domain near the carboxyl terminus of Vpr at residue 73 (arginine) and have demonstrated that alterations at this residue result in ablation of transcriptional activity of Vpr and its ability to block cell cycle events at the G
2
stage. Interestingly, substitution mutations at R73 have resulted in a peptide with dominant negative activities on wild-type functions in transcription and host proliferation events. Results from in vitro and in vivo protein-protein interaction studies have revealed that functionally inactive mutant Vpr can be associated with wild-type protein, presumably through the N-terminal regions of the protein which have been shown to be important for Vpr oligomerization. Thus, it is likely that complexation of the mutant Vpr with wild-type protein functionally inactivates Vpr. The importance of these findings in light of the development of therapeutic strategies is discussed.
Maternally Transferred Antibodies from DNA-Immunized Avians Protect Offspring against Hepadnavirus Infection
Authors: Rollier Christine , Charollois Celine , Jamard Catherine , Trepo Christian , Cova Lucyna
Published: July 2002

The outcome and protective efficacy of maternal antibodies elicited by DNA immunization to the large (L) hepadnavirus envelope protein were studied using the duck hepatitis B virus (DHBV) model. Following genetic immunization of breeding ducks with a DHBV L protein gene-bearing plasmid, specific and highly neutralizing antibodies were transferred from the sera of immunized ducks, via the egg yolk, to the progeny of vaccinees. Interestingly, large amounts (60 to 100 mg/egg) of high-titer and L protein-specific yolk immunoglobulins (immunoglobulin Y) accumulated in the egg yolk. These results suggest that eggs from genetically immunized avians may represent a potent source of DNA-designed antibodies specific to viral antigen. Importantly, these antibodies are vertically transmitted and protect offspring against high-titer DHBV challenge.
Characterization of a Baculovirus Alkaline Nuclease
Authors: Li Lulin , Rohrmann George F.
Published: July 2002

All baculovirus genomes sequenced to date encode a homolog of an alkaline nuclease that has been characterized in the
Herpesviridae
. In this report we describe the characterization of the alkaline nuclease (AN) homolog of the
Autographa californica
multinucleocapsid nucleopolyhedrovirus (Ac
M
NPV) (open reading frame 133). His-tagged AN constructs were expressed in recombinant baculoviruses and affinity purified, and then their enzymatic activity was characterized. AN was found to degrade linear DNA at alkaline pH, preferred Mg
2+
over Mn
2+
, had optimal activity at 35°C, and did not appear to have a salt requirement. To rule out contamination by the endogenous baculovirus gene product or a cellular enzyme, point mutations were introduced into a highly conserved domain of the gene. These mutations were found to markedly reduce or eliminate most of the activity of the affinity-purified enzyme. An antibody generated against the protein was used to analyze its expression by Western blot analysis. AN was found to be expressed at low levels by 12 h postinfection, with maximal expression at 24 h postinfection. Attempts to generate a virus with this gene inactivated were unsuccessful, suggesting that AN may be encoded by an essential gene.
Enhanced Infectivity of an R5-Tropic Simian/Human Immunodeficiency Virus Carrying Human Immunodeficiency Virus Type 1 Subtype C Envelope after Serial Passages in Pig-Tailed Macaques (
Macaca nemestrina
)
Authors: Chen Zhiwei , Huang Yaoxing , Zhao Xiuqing , Skulsky Eva , Lin Dorothy , Ip James , Gettie Agegnehu , Ho David D.
Published: July 2002

The increasing prevalence of human immunodeficiency virus type 1 (HIV-1) subtype C infection worldwide calls for efforts to develop a relevant animal model for evaluating strategies against the transmission of the virus. A chimeric simian/human immunodeficiency virus (SHIV), SHIV
CHN19
, was generated with a primary, non-syncytium-inducing HIV-1 subtype C envelope from a Chinese strain in the background of SHIV
33
. Unlike R5-tropic SHIV
162
, SHIV
CHN19
was not found to replicate in rhesus CD4
+
T lymphocytes. SHIV
CHN19
does, however, replicate in CD4
+
T lymphocytes of pig-tailed macaques (
Macaca nemestrina
). The observed replication competence of SHIV
CHN19
requires the full
tat/rev
genes and partial gp41 region derived from SHIV
33
. To evaluate in vivo infectivity, SHIV
CHN19
was intravenously inoculated, at first, into two pig-tailed and two rhesus macaques. Although all four animals became infected, the virus replicated preferentially in pig-tailed macaques with an earlier plasma viral peak and a faster seroconversion. To determine whether in vivo adaptation would enhance the infectivity of SHIV
CHN19
, passages were carried out serially in three groups of two pig-tailed macaques each, via intravenous blood-bone marrow transfusion. The passages greatly enhanced the infectivity of the virus as shown by the increasingly elevated viral loads during acute infection in animals with each passage. Moreover, the doubling time of plasma virus during acute infection became much shorter in passage 4 (P4) animals (0.2 day) in comparison to P1 animals (1 to 2 days). P2 to P4 animals all became seropositive around 2 to 3 weeks postinoculation and had a decline in CD4/CD8 T-cell ratio during the early phase of infection. In P4 animals, a profound depletion of CD4 T cells in the lamina propria of the jejunum was observed. Persistent plasma viremia has been found in most of the infected animals with sustained viral loads ranging from 10
3
to 10
5
per ml up to 6 months postinfection. Serial passages did not change the viral phenotype as confirmed by the persistence of the R5 tropism of SHIV
CHN19
isolated from P4 animals. In addition, the infectivity of SHIV
CHN19
in rhesus peripheral blood mononuclear cells was also increased after in vivo passages. Our data indicate that SHIV
CHN19
has adapted well to grow in macaque cells. This established R5-tropic SHIV
CHN19
/macaque model would be very useful for HIV-1 subtype C vaccine and pathogenesis studies.
Human Immunodeficiency Virus Type 1 Vpr Contains Two Leucine-Rich Helices That Mediate Glucocorticoid Receptor Coactivation Independently of Its Effects on G
2
Cell Cycle Arrest
Authors: Sherman Michael P. , de Noronha Carlos M. C. , Pearce David , Greene Warner C.
Published: July 2002

Human immunodeficiency virus type 1 (HIV-1) Vpr participates in nuclear targeting of the viral preintegration complex in nondividing cells and induces G
2
cell cycle arrest in proliferating cells, which creates an intracellular milieu favorable for viral replication. Vpr also activates the transcription of several promoters and enhancers by a poorly understood mechanism. Vpr enhances glucocorticoid receptor (GR) signaling and may mediate the effects of steroids on HIV replication. More specifically, recombinant Vpr can potentiate virion production from U937 cells, downregulate NF-κB induction, and enhance programmed cell death, all effects also mediated by glucocorticoids. Vpr has been proposed to act as a GR coactivator, although other studies suggest that these enhancing effects are merely a consequence of G
2
cell cycle arrest. We now demonstrate that Vpr functions as a GR coactivator and that this activity is independent of cell cycle arrest. In addition, we show that the Vpr-induced coactivation requires an intact glucocorticoid response element, that it is dependent on the presence of hormone and the corresponding receptor, and that it is mediated by the two highly conserved leucine-rich domains within Vpr that resemble the GR coactivator signature motif.
Granulocyte-Macrophage Colony-Stimulating Factor Priming plus Papillomavirus E6 DNA Vaccination: Effects on Papilloma Formation and Regression in the Cottontail Rabbit Papillomavirus-Rabbit Model
Authors: Leachman Sancy A. , Tigelaar Robert E. , Shlyankevich Mark , Slade Martin D. , Irwin Michele , Chang Ed , Wu T. C. , Xiao Wei , Pazhani Sundaram , Zelterman Daniel , Brandsma Janet L.
Published: July 2002

A cottontail rabbit papillomavirus (CRPV) E6 DNA vaccine that induces significant protection against CRPV challenge was used in a superior vaccination regimen in which the cutaneous sites of vaccination were primed with an expression vector encoding granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that induces differentiation and local recruitment of professional antigen-presenting cells. This treatment induced a massive influx of major histocompatibility complex class II-positive cells. In a vaccination-challenge experiment, rabbit groups were treated by E6 DNA vaccination, GM-CSF DNA inoculation, or a combination of both treatments. After two immunizations, rabbits were challenged with CRPV at low, moderate, and high stringencies and monitored for papilloma formation. As expected, all clinical outcomes were monotonically related to the stringency of the viral challenge. The results demonstrate that GM-CSF priming greatly augmented the effects of CRPV E6 vaccination. First, challenge sites in control rabbits (at the moderate challenge stringency) had a 0% probability of remaining disease free, versus a 50% probability in E6-vaccinated rabbits, and whereas GM-CSF alone had no effect, the interaction between GM-CSF priming and E6 vaccination increased disease-free survival to 67%. Second, the incubation period before papilloma onset was lengthened by E6 DNA vaccination alone or to some extent by GM-CSF DNA inoculation alone, and the combination of treatments induced additive effects. Third, the rate of papilloma growth was reduced by E6 vaccination and, to a lesser extent, by GM-CSF treatment. In addition, the interaction between the E6 and GM-CSF treatments was synergistic and yielded more than a 99% reduction in papilloma volume. Finally, regression occurred among the papillomas that formed in rabbits treated with the E6 vaccine and/or with GM-CSF, with the highest regression frequency occurring in rabbits that received the combination treatment.
Leader Proteinase of the Beet Yellows Closterovirus: Mutation Analysis of the Function in Genome Amplification
Authors: Peng Chih-Wen , Dolja Valerian V.
Published: July 2002

The beet yellows closterovirus leader proteinase (L-Pro) possesses a C-terminal proteinase domain and a nonproteolytic N-terminal domain. It was found that although L-Pro is not essential for basal-level replication, deletion of its N-terminal domain resulted in a 1,000-fold reduction in RNA accumulation. Mutagenic analysis of the N-terminal domain revealed its structural flexibility except for the 54-codon-long, 5′-terminal element in the corresponding open reading frame that is critical for efficient RNA amplification at both RNA and protein levels.
Alphavirus RNA Genome Repair and Evolution: Molecular Characterization of Infectious Sindbis Virus Isolates Lacking a Known Conserved Motif at the 3′ End of the Genome
Authors: George Jyothi , Raju Ramaswamy
Published: July 2002

The 3′ nontranslated region of the genomes of Sindbis virus (SIN) and other alphaviruses carries several repeat sequence elements (RSEs) as well as a 19-nucleotide (nt) conserved sequence element (3′CSE). The 3′CSE and the adjoining poly(A) tail of the SIN genome are thought to act as viral promoters for negative-sense RNA synthesis and genome replication. Eight different SIN isolates that carry altered 3′CSEs were studied in detail to evaluate the role of the 3′CSE in genome replication. The salient findings of this study as it applies to SIN infection of BHK cells are as follows: i) the classical 19-nt 3′CSE of the SIN genome is not essential for genome replication, long-term stability, or packaging; ii) compensatory amino acid or nucleotide changes within the SIN genomes are not required to counteract base changes in the 3′ terminal motifs of the SIN genome; iii) the 5′ 1-kb regions of all SIN genomes, regardless of the differences in 3′ terminal motifs, do not undergo any base changes even after 18 passages; iv) although extensive addition of AU-rich motifs occurs in the SIN genomes carrying defective 3′CSE, these are not essential for genome viability or function; and v) the newly added AU-rich motifs are composed predominantly of RSEs. These findings are consistent with the idea that the 3′ terminal AU-rich motifs of the SIN genomes do not bind directly to the viral polymerase and that cellular proteins with broad AU-rich binding specificity may mediate this interaction. In addition to the classical 3′CSE, other RNA motifs located elsewhere in the SIN genome must play a major role in template selection by the SIN RNA polymerase.
Persistence and Tissue Distribution of DNA in Normal and Immunodeficient Mice Inoculated with Polyomavirus VP1 Pseudocapsid Complexes or Polyomavirus
Authors: Heidari S. , Krauzewicz N. , Kalantari M. , Vlastos A. , Griffin B. E. , Dalianis T.
Published: July 2002

Introduction of DNA into normal and immunodeficient mice, alone or in complex with VP1 pseudocapsids, has been compared to DNA transfer by viral infection. Similar to natural infection and in contrast to plasmid alone, VP1 pseudocapsids efficiently introduced DNA, which remained for months in normal mice and possibly longer in B- and T-cell-deficient mice.
Humoral Immunity to Adeno-Associated Virus Type 2 Vectors following Administration to Murine and Nonhuman Primate Muscle
Authors: Chirmule Narendra , Xiao Weidong , Truneh Alemseged , Schnell Michael A. , Hughes Joseph V. , Zoltick Philip , Wilson James M.
Published: July 2002

Adeno-associated virus (AAV) is being developed as a vector capable of conferring long-term gene expression, which is useful in the treatment of chronic diseases. In most therapeutic applications, it is necessary to readminister the vector. This study characterizes the humoral immune response to AAV capsid proteins following intramuscular injection and its impact on vector readministration. Studies of mice and rhesus monkeys demonstrated the formation of neutralizing antibodies to AAV capsid proteins that persisted for over 1 year and then diminished, but this did not prevent the efficacy of vector readministration. More-detailed studies strongly suggested that the B-cell response was T cell dependent. This was further evaluated with a blocking antibody to human CD4, primatized for clinical trials, in a biologically compatible mouse in which the endogenous murine CD4 gene was functionally replaced with the human counterpart. Transient pharmacologic inhibition of CD4 T cells with CD4 antibody prevented an antivector response long after the effects of the CD4 antibody diminished; readministration of vector without diminution of gene expression was possible. Our studies suggest that truly durable transgene expression (i.e., prolonged genetic engraftment together with vector readministration) is possible with AAV in skeletal muscle, although it will be necessary to transiently inhibit CD4 T-cell function to avoid the activation of memory B cells.
Rinderpest Viruses Lacking the C and V Proteins Show Specific Defects in Growth and Transcription of Viral RNAs
Authors: Baron Michael D. , Barrett Thomas
Published: July 2002

Rinderpest virus
is a morbillivirus and the causative agent of an important disease of cattle and wild bovids. The P genes of all morbilliviruses give rise to two proteins in addition to the P protein itself: use of an alternate start translation site, in a second open reading frame, gives rise to the C protein, while cotranscriptional insertion of an extra base gives rise to the V protein, a fusion of the amino-terminal half of P to a short, highly conserved, cysteine-rich zinc binding domain. Little is known about the function of either of these two proteins in the rinderpest virus life cycle. We have constructed recombinant rinderpest viruses in which the expression of these proteins has been suppressed, individually and together, and studied the replication of these viruses in tissue culture. We show that the absence of the V protein has little effect on the replication rate of the virus but does lead to an increase in synthesis of genome and antigenome RNAs and a change in cytopathic effect to a more syncytium-forming phenotype. Virus that does not express the C protein, on the other hand, is clearly defective in growth in all cell lines tested, and this defect appears to be related to a decreased transcription of mRNA from viral genes. The phenotypes of both individual mutant virus types are both expressed in the double mutant expressing neither V nor C.
Activation of Lymphocyte Signaling by the R1 Protein of Rhesus Monkey Rhadinovirus
Authors: Damania Blossom , DeMaria Maryann , Jung Jae U. , Desrosiers Ronald C.
Published: July 2002

Rhesus monkey rhadinovirus(RRV) is a gamma-2 herpesvirus that exhibits a considerable degree of similarity to the humanKaposi's sarcoma-associated herpesvirus(KSHV). The R1 protein of RRV is distantly related to the K1 protein of KSHV, and R1, like K1, can contribute to cell growth transformation. In this study we analyzed the ability of the cytoplasmic tail of R1 to function as a signal transducer. The cytoplasmic domain of the R1 protein contains several tyrosine residues whose phosphorylation is induced in cells expressing Syk kinase. Expression of a CD8 chimera protein containing the extracellular and transmembrane domains of CD8 fused to the cytoplasmic domain of R1 mobilized intracellular calcium and induced cellular tyrosine phosphorylation in B cells upon stimulation with anti-CD8 antibody. None of the CD8-R1 cytoplasmic deletion mutants tested were able to mobilize intracellular calcium or to induce tyrosine phosphorylation to a significant extent upon addition of anti-CD8 antibody. Expression of wild-type R1 protein activated nuclear factor of activated T lymphocytes (NFAT) eightfold in B cells in the absence of antibody stimulation; expression of the CD8-R1C chimera strongly induced NFAT activity (60-fold) but only upon the addition of anti-CD8 antibody. We conclude that the cytoplasmic domain of R1 is capable of transducing signals that elicit B-lymphocyte activation events. The signal-inducing properties of R1 appear to be similar to those of K1 but differ in that the required sequences are distributed over a much longer stretch of the cytoplasmic domain (>150 amino acids). In addition, the induction of calcium mobilization was considerably longer in duration and stronger with R1 than with K1.
Mengovirus and Encephalomyocarditis Virus Poly(C) Tract Lengths Can Affect Virus Growth in Murine Cell Culture
Authors: Martin Lee R. , Neal Zane C. , McBride M. Scott , Palmenberg Ann C.
Published: July 2002

Many virulent aphthoviruses and cardioviruses have long homopolymeric poly(C) tracts in the 5′ untranslated regions of their RNA genomes. A panel of genetically engineered mengo-type cardioviruses has been described which contain a variety of different poly(C) tract lengths. Studies of these viruses have shown the poly(C) tract to be dispensable for growth in HeLa cells, although the relative murine virulence of the viruses correlates directly and positively with tract length. Compared with wild-type mengovirus strain M, mutants with shortened poly(C) tracts grow poorly in mice and protectively immunize rather than kill recipient animals. In the present study, several murine cell populations were tested to determine whether, unlike HeLa cells, they allowed a differential amplification of viruses with long or short poly(C) tracts. Replication and cytopathic studies with four hematopoietically derived cell lines (CH2B, RAW 264.7, A20.J, and P815) and two murine fibroblast cell lines [L929 and L(Y)] demonstrated that several of these cell types indeed allowed differential virus replication as a function of viral poly(C) tract length. Among the most discerning of these cells, RAW 264.7 macrophages supported vigorous lytic growth of a long-tract virus, vMwt (C
44
UC
10
), but supported only substantially diminished and virtually nonlytic growth of vMC
24
(C
13
UC
10
) and vMC
0
short-tract viruses. The viral growth differences evident in all cell lines were apparent early and continuously during every cycle of virus amplification. The data suggest that poly(C) tract-dependent attenuation of mengovirus may be due in part to a viral replication defect manifest in similar hematopoietic-type cells shortly after murine infection. The characterized cultures should provide excellent tools for molecular study of poly(C) tract-mediated virulence.
An Adeno-Associated Virus (AAV) Initiator Protein, Rep78, Catalyzes the Cleavage and Ligation of Single-Stranded AAV
ori
DNA
Authors: Smith Richard H. , Kotin Robert M.
Published: July 2002

The Rep78 protein of adeno-associated virus (AAV) contains amino acid sequence motifs common to rolling-circle replication (RCR) initiator proteins. In this report, we describe RCR initiator-like activities of Rep78. We demonstrate that a maltose-binding protein (MBP)–Rep78 fusion protein can catalyze the cleavage and ligation of single-stranded DNA substrates derived from the AAV origin of replication. Rep-mediated single-stranded DNA cleavage was strictly dependent on the presence of certain divalent cations (e.g., Mn
2+
or Mg
2+
) but did not require the presence of a nucleoside triphosphate cofactor. Electrophoretic mobility shift assays demonstrated that binding of single-stranded DNA by MBP-Rep78 was influenced by the length of the substrate as well as the presence of potential single-stranded
cis
-acting sequence elements. Site-directed mutagenesis was used to examine the role of specific tyrosine residues within a conserved RCR motif (motif 3) of Rep78. Replacement of Tyr-156 with phenylalanine abolished the ability of MBP-Rep78 to mediate the cleavage and ligation of single-stranded DNA substrates but not the ability to stably bind single-stranded DNA. The cleaving-joining activity of Rep78 is consistent with the mechanism of replicative intermediate dimer resolution proposed for the autonomous parvoviruses and may have implications for targeted integration of recombinant AAV vectors.
Induction of Potent Human Immunodeficiency Virus Type 1-Specific T-Cell-Restricted Immunity by Genetically Modified Dendritic Cells
Authors: Lisziewicz Julianna , Gabrilovich Dmitry I. , Varga Georg , Xu Jianqing , Greenberg Philip D. , Arya Suresh K. , Bosch Marnix , Behr Jean-Paul , Lori Franco
Published: July 2002

A novel technology combining replication- and integration-defective human immunodeficiency virus type 1 (HIV-1) vectors with genetically modified dendritic cells was developed in order to induce T-cell immunity. We introduced the vector into dendritic cells as a plasmid DNA using polyethylenimine as the gene delivery system, thereby circumventing the problem of obtaining viral vector expression in the absence of integration. Genetically modified dendritic cells (GMDC) presented viral epitopes efficiently, secreted interleukin 12, and primed both CD4+and CD8+HIV-specific T cells capable of producing gamma interferon and exerting potent HIV-1-specific cytotoxicity in vitro. In nonhuman primates, subcutaneously injected GMDC migrated into the draining lymph node at an unprecedentedly high rate and expressed the plasmid DNA. The animals presented a vigorous HIV-specific effector cytotoxic-T-lymphocyte (CTL) response as early as 3 weeks after a single immunization, which later developed into a memory CTL response. Interestingly, antibodies did not accompany these CTL responses, indicating that GMDC can induce a pure Th1 type of immune response. Successful induction of a broad and long-lasting HIV-specific cellular immunity is expected to control virus replication in infected individuals.
Ex Vivo Stimulation and Expansion of both CD4+and CD8+T Cells from Peripheral Blood Mononuclear Cells of Human Cytomegalovirus-Seropositive Blood Donors by Using a Soluble Recombinant Chimeric Protein, IE1-pp65
Authors: Vaz-Santiago Jocelyn , Lulé Jacqueline , Rohrlich Pierre , Jacquier Céline , Gibert Nicolas , Le Roy Emmanuelle , Betbeder Didier , Davignon Jean-Luc , Davrinche Christian
Published: July 2002

The transfer of anti-human cytomegalovirus (HCMV) effector T cells to allogeneic bone marrow recipients results in protection from HCMV disease associated with transplantation, suggesting the direct control of CMV replication by T cells. IE1 and pp65 proteins, both targets of CD4+and CD8+T cells, are considered the best candidates for immunotherapy and vaccine design against HCMV. In this report, we describe the purification of a 165-kDa chimeric protein, IE1-pp65, and its use for in vitro stimulation and expansion of anti-HCMV CD4+and CD8+T cells from peripheral blood mononuclear cells (PBMC) of HCMV-seropositive donors. We demonstrate that an important proportion of anti-HCMV CD4+T cells was directed against IE1-pp65 in HCMV-seropositive donors and that the protein induced activation of HLA-DR3-restricted anti-IE1 CD4+T-cell clones, as assessed by gamma interferon (IFN-γ) secretion and cytotoxicity. Moreover, soluble IE1-pp65 stimulated and expanded anti-pp65 CD8+T cells from PBMC of HLA-A2, HLA-B35, and HLA-B7 HCMV-seropositive blood donors, as demonstrated by cytotoxicity, intracellular IFN-γ labeling, and quantitation of peptide-specific CD8+cells using an HLA-A2–peptide tetramer and staining of intracellular IFN-γ. These results suggest that soluble IE1-pp65 may provide an alternative to infectious viruses used in current adoptive strategies of immunotherapy.
Human T-Cell Leukemia Virus Type 1 Receptor Expression among Syncytium-Resistant Cell Lines Revealed by a Novel Surface Glycoprotein-Immunoadhesin
Authors: Jassal Sushma R. , Pöhler Richard G. , Brighty David W.
Published: July 2002

The envelope glycoproteins of human T-cell leukemia virus type 1 (HTLV-1) perform functions that are crucial for virus entry into cells. The surface glycoprotein (SU) is responsible for viral recognition of, and binding to, target cells through its interaction with an unknown cell surface receptor. To facilitate molecular analysis of the receptor-binding properties of SU and to characterize the cellular receptor employed by HTLV-1, we have expressed a recombinant SU fused to the Fc domain of human immunoglobulin G. Here, we demonstrate that this novel SU-immunoadhesin retains both the biochemical properties of Fc and the receptor-binding specificity of the HTLV-1 SU. We use this SU-immunoadhesin to demonstrate, by direct cell surface binding assays, that the receptor used by HTLV-1 has been conserved through vertebrate evolution. Moreover, using murine-human somatic cell hybrids we provide data that do not support the previously assigned location for the HTLV-1 receptor on human chromosome 17. Most importantly, we show that many cell lines that are resistant to HTLV-1 envelope-mediated infection and syncytium formation express functional receptors that are recognized by the HTLV-1 SU. Based on our results, we suggest that for some HTLV-1-resistant cell lines the block to viral entry occurs at a late post-receptor-binding step of the entry process. Our findings will be of value in developing new strategies to identify the cellular receptor used by HTLV-1.
Transient Disruption of Intercellular Junctions Enables Baculovirus Entry into Nondividing Hepatocytes
Authors: Bilello John P. , Delaney William E. , Boyce Frederick M. , Isom Harriet C.
Published: July 2002

Baculovirus infection has extended the capabilities for transfection of exogenous genes into a variety of mammalian cell types. Because rat hepatocytes plated on collagen-coated dishes and maintained in dimethyl sulfoxide (DMSO)-supplemented chemically defined medium are an excellent model system for studying liver function in vitro, we investigated the ability of baculoviruses to infect and deliver exogenous genes to cells in this culture system. Efficient delivery to hepatocytes in short-term culture becomes restricted to peripheral cells, or “edge” cells, as the hepatocytes acquire intercellular junctions and form islands with time in culture. This barrier to baculovirus entry can be overcome, and the percentage of internal cells within the hepatocyte islands that are infected with the baculovirus can be increased more than 100-fold, when cells are subjected to transient calcium depletion before and during infection. These findings suggest that at least in some cell types, such as hepatocytes, baculovirus entry may require contact with the basolateral surface. We conclude from this study that recombinant baculovirus infection following transient depletion of extracellular calcium results in delivery of exogenous genes to at least 75% of hepatocytes in long-term DMSO culture, thereby making it possible for the first time to carry out gain-of-function and loss-of-function studies in this cell system.
Inhibition of Major Histocompatibility Complex Class II-Dependent Antigen Presentation by Neutralization of Gamma Interferon Leads to Breakdown of Resistance against Measles Virus-Induced Encephalitis
Authors: Weidinger Gerald , Henning Golo , ter Meulen Volker , Niewiesk Stefan
Published: July 2002

BALB/c mice are resistant to measles virus (MV)-induced encephalitis due to their strong MV-specific CD4+T-cell response. Resistance is broken by neutralization of gamma interferon with monoclonal antibodies, indicating an important role for this pleiotropic cytokine. Here, we demonstrate that mouse gamma interferon has no direct antiviral effect in vitro and in vivo. The breakdown of resistance is due neither to a switch in the T-helper response nor to an impaired migration of CD4+T cells. Neutralization of gamma interferon interferes with the major histocompatibility complex class II-dependent antigen presentation and subsequent proliferation of CD4+T cells in vitro and in vivo. In consequence, the reduction in numbers of CD4+T cells below a protective threshold leads to susceptibility to MV-induced encephalitis.
Kaposi's Sarcoma-Associated Herpesvirus K-bZIP Protein Is Phosphorylated by Cyclin-Dependent Kinases
Authors: Polson Andrew G. , Huang Lan , Lukac David M. , Blethrow Justin D. , Morgan David O. , Burlingame Alma L. , Ganem Don
Published: July 2002

The K8 locus in Kaposi's sarcoma-associated herpesvirus (KSHV) is syntenic with the Epstein-Barr virus (EBV) BZLF (Z) locus and expresses three alternatively spliced transcripts. The fully spliced transcript encodes K-bZIP, the KSHV homologue of the EBV immediate-early transcriptional transactivator Z. Here we show that despite the presence of alternatively spliced transcripts, the protein from the fully spliced RNA, K-bZIP, is the principal product detectable in KSHV-infected B cells. The protein is detected only in lytically infected cells and is localized to the nucleus. We further characterized K-bZIP by determining its phosphorylation status. Phosphoamino acid analysis revealed phosphorylation on serine and threonine. Analysis of the sites of K-bZIP phosphorylation by tandem mass spectrometry revealed that K-bZIP was phosphorylated on Thr 111 and Ser 167. These phosphorylation sites are contained within cyclin-dependent kinase (CDK) recognition sites with the consensus sequence (S/T)PXR, suggesting that K-bZIP could be phosphorylated by CDKs. We tested this hypothesis using an in vitro kinase reaction performed in whole-cell extracts that resemble in vivo conditions more closely than standard in vitro kinase reactions. We found that the three CDK-cyclin complexes we tested phosphorylated K-bZIP but not the control ORF 73 protein, which contains four (S/T)PXR sites. Ectopic expression of K-bZIP cannot reactivate KSHV from latency, and single and double mutants of K-bZIP in which alanines replaced the phosphorylated serine and/or threonine also failed to induce lytic replication. These studies indicate that K-bZIP is a substrate for CDKs and should inform further functional analyses of the protein.
Restoration of Anti-Human Immunodeficiency Virus Type 1 (HIV-1) Responses in CD8+T Cells from Late-Stage Patients on Prolonged Antiretroviral Therapy by Stimulation In Vitro with HIV-1 Protein-Loaded Dendritic Cells
Authors: Fan Zheng , Huang Xiao-Li , Borowski Luann , Mellors John W. , Rinaldo Charles R.
Published: July 2002

We demonstrate that dendritic cells loaded in vitro with human immunodeficiency virus type 1 (HIV-1) protein-liposome complexes activate HLA class I-restricted anti-HIV-1 cytotoxic T-lymphocyte and gamma interferon (IFN-γ) responses in autologous CD8+T cells from late-stage HIV-1-infected patients on prolonged combination drug therapy. Interleukin-12 enhanced this effect through an interleukin-2- and IFN-γ-mediated pathway. This suggests that dendritic cells from HIV-1-infected persons can be engineered to evoke stronger anti-HIV-1 CD8+T-cell reactivity as a strategy to augment antiretroviral therapy.
Complete Sequence of a Novel Highly Divergent Simian T-Cell Lymphotropic Virus from Wild-Caught Red-Capped Mangabeys (
Cercocebus torquatus
) from Cameroon: a New Primate T-Lymphotropic Virus Type 3 Subtype
Authors: Meertens Laurent , Mahieux Renaud , Mauclère Philippe , Lewis John , Gessain Antoine
Published: July 2002

Among 65 samples obtained from a primate rescue center located in Cameroon, two female adult red-capped mangabeys (
Cercocebus torquatus
) (CTO-602 and CTO-604), of wild-caught origin, had a peculiar human T-cell lymphotropic virus type 2 (HTLV-2)-like Western blot seroreactivity (p24, RGD21, +/-K55). Analyses of the simian T-cell lymphotropic virus type 3 (STLV-3)/CTO-604 complete proviral sequence (8,919 bp) indicated that this novel strain was highly divergent from HTLV-1 (60% nucleotide similarity), HTLV-2 (62%), or STLV-2 (62%) prototypes. It was, however, related to STLV-3/PH-969 (87%), a divergent STLV strain previously isolated from an Eritrean baboon. The STLV-3/CTO-604 sequence possesses the major open reading frames corresponding to the structural, enzymatic, and regulatory proteins. However, its long terminal repeat is shorter, with only two 21-bp repeats. Furthermore, as demonstrated by reverse transcriptase PCR, this new STLV exhibits significant differences from STLV-3/PH-969 at the mRNA splice junction position level. In all phylogenetic analyses, STLV-3/CTO-604 and STLV-3/PH-969 clustered in a highly supported single clade, indicating an evolutionary lineage independent from primate T-lymphotropic virus type 1 (PTLV-1) and PTLV-2. Nevertheless, the nucleotide divergence between STLV-3/PH-969 and STLV-3/CTO-604 is equivalent to or higher than the divergence observed between the different HTLV-1 or HTLV-2 subtypes. Thus, the STLV-3/CTO-604 strain can be considered the prototype of a second subtype in the PTLV-3 type. The presence of two related viruses in evolutionarily distantly related African monkeys species, living in two opposite ecosystems (rain forest versus desert), reinforces the possible African origin of PTLV and opens new avenues regarding the search for a possible human counterpart of these viruses in individuals exhibiting such HTLV-2-like seroreactivities.
Identification of Amino Acid Residues of gp130 Signal Transducer and gp80 α Receptor Subunit That Are Involved in Ligand Binding and Signaling by Human Herpesvirus 8-Encoded Interleukin-6
Authors: Li Hong , Nicholas John
Published: July 2002

Human herpesvirus 8-encoded interleukin-6 (vIL-6) signals through the gp130 signal transducer but is not dependent on the IL-6 receptor α subunit (IL-6R, gp80) that is required for signaling by endogenous IL-6 proteins; however, IL-6R can enhance vIL-6 activity and can enable signaling through a gp130 variant, gp130.PM5, that is itself unable to support vIL-6 signaling. These findings suggest that the vIL-6-gp130 interactions are qualitatively different from those of human IL-6 (hIL-6) and that vIL-6 signaling may be more promiscuous than that of hIL-6 but that IL-6R may play a role in vIL-6 signaling in vivo. To examine the receptor binding requirements of vIL-6, we have undertaken mutational analyses of regions of gp130 and IL-6R potentially involved in interactions with ligand or in functional complex formation and used these variants in functional, ligand-binding, and receptor dimerization assays. The data presented identify positions within two interstrand loops of the gp130 cytokine-receptor homology domain that are important for vIL-6 signaling and vIL-6-induced receptor dimerization and show that vIL-6, like hIL-6, can form complexes with IL-6R and gp130 but that the roles of putative cytokine-binding residues of IL-6R in ligand-induced functional complex formation are qualitatively different in the case of vIL-6 and hIL-6.
Comprehensive Analysis of CD8+-T-Cell Responses against Hepatitis C Virus Reveals Multiple Unpredicted Specificities
Authors: Lauer Georg M. , Ouchi Kei , Chung Raymond T. , Nguyen Tam N. , Day Cheryl L. , Purkis Deborah R. , Reiser Markus , Kim Arthur Y. , Lucas Michaela , Klenerman Paul , Walker Bruce D.
Published: July 2002

The hepatitis C virus (HCV)-specific CD8+-T-cell response is thought to play a critical role in HCV infection. Studies of these responses have largely relied on the analysis of a small number of previously described or predicted HCV epitopes, mostly restricted by HLA A2. In order to determine the actual breadth and magnitude of CD8+-T-cell responses in the context of diverse HLA class I alleles, we performed a comprehensive analysis of responses to all expressed HCV proteins. By using a panel of 301 overlapping peptides, we analyzed peripheral blood mononuclear cells (PBMC) from a cohort of 14 anti-HCV-positive, HLA A2-positive individuals in an enzyme-linked immunospot assay. Only four subjects had detectable HLA A2-restricted responses in PBMC, and only 3 of 19 predicted A2 epitopes were targeted, all of which were confirmed by tetramer analysis. In contrast, 9 of 14 persons showed responses with more comprehensive analyses, with many responses directed against previously unreported epitopes. These results indicate that circulating HCV-specific CD8+-T-cell responses can be detected in PBMC in the majority of infected persons and that these responses are heterogeneous with no immunodominant epitopes consistently recognized. Since responses to epitopes restricted by single HLA alleles such as HLA A2 do not predict the overall response in an individual, more comprehensive approaches, as shown here, should facilitate definition of the role of the CD8+-T-cell response in HCV infection. Moreover, the low level or absence of responses to many predicted epitopes provides a rationale for immunotherapeutic interventions to broaden cytotoxic-T-lymphocyte recognition.
Increased CCR5 Affinity and Reduced CCR5/CD4 Dependence of a Neurovirulent Primary Human Immunodeficiency Virus Type 1 Isolate
Authors: Gorry Paul R. , Taylor Joann , Holm Geoffrey H. , Mehle Andrew , Morgan Tom , Cayabyab Mark , Farzan Michael , Wang Hui , Bell Jeanne E. , Kunstman Kevin , Moore John P. , Wolinsky Steven M. , Gabuzda Dana
Published: July 2002

Most human immunodeficiency virus type 1 (HIV-1) viruses in the brain use CCR5 as the principal coreceptor for entry into a cell. However, additional phenotypic characteristics are necessary for HIV-1 neurotropism. Furthermore, neurotropic strains are not necessarily neurovirulent. To better understand the determinants of HIV-1 neurovirulence, we isolated viruses from brain tissue samples from three AIDS patients with dementia and HIV-1 encephalitis and analyzed their ability to induce syncytia in monocyte-derived macrophages (MDM) and neuronal apoptosis in primary brain cultures. Two R5X4 viruses (MACS1-br and MACS1-spln) were highly fusogenic in MDM and induced neuronal apoptosis. The R5 viruses UK1-br and MACS2-br are both neurotropic. However, only UK1-br induced high levels of fusion in MDM and neuronal apoptosis. Full-length Env clones from UK1-br required lower CCR5 and CD4 levels than Env clones from MACS2-br to function efficiently in cell-to-cell fusion and single-round infection assays. UK1-br Envs also had a greater affinity for CCR5 than MACS2-br Envs in binding assays. Relatively high levels of UK1-br and MACS2-br Envs bound to CCR5 in the absence of soluble CD4. However, these Envs could not mediate CD4-independent infection, and MACS2-br Envs were unable to mediate fusion or infection in cells expressing low levels of CD4. The UK1-br virus was more resistant than MACS2-br to inhibition by the CCR5-targeted inhibitors TAK-779 and Sch-C. UK1-br was more sensitive than MACS2-br to neutralization by monoclonal antibodies (2F5 and immunoglobulin G1b12 [IgG1b12]) and CD4-IgG2. These results predict the presence of HIV-1 variants with increased CCR5 affinity and reduced dependence on CCR5 and CD4 in the brains of some AIDS patients with central nervous system disease and suggest that R5 variants with increased CCR5 affinity may represent a pathogenic viral phenotype contributing to the neurodegenerative manifestations of AIDS.
Differential Effect of Murine Alpha/Beta Interferon Transgenes on Antagonization of Herpes Simplex Virus Type 1 Replication
Authors: Härle Peter , Cull Vanessa , Agbaga Martin-Paul , Silverman Robert , Williams Bryan R. G. , James Cassandra , Carr Daniel J. J.
Published: July 2002

Alpha/beta interferons (IFN-α/β) are potent, endogenous antiviral cytokines that suppress the replication of RNA and DNA viruses, including herpes simplex virus type 1 (HSV-1). The present study compared the efficacies of IFN-α/β transgenes, including IFN-α1, -α4, -α5, -α6, -α9, and -β, against HSV-1 infection. L929 cells transfected with the IFN-α/β transgenes produced similar levels of IFN, as measured by bioassay and enzyme-linked immunosorbent assay. In addition, transfected cells were less susceptible to HSV-1 infection than were cells transfected with a plasmid vector control. The murine IFN-β plasmid construct exhibited the greatest reduction, while the murine IFN-α5 transgene showed a modest inhibitory effect in viral titers recovered from the supernatants of transfected, infected L929 cultures. Consistent with this observation, the IFN-β transgene antagonized viral transcript levels, including infected cell protein 27, thymidine kinase, and glycoprotein B, to a greater extent than did the IFN-α transgenes at 6 to 10 h postinfection as determined by real-time PCR. Cells transfected with the IFN-α4, IFN-α9, or IFN-β transgenes showed the greatest reduction in viral protein expression relative to the other transfected cells, which was associated with increased STAT1 expression. The absence of the IFN-responsive protein kinase R (PKR) gene completely abrogated the antiviral induction by all IFN-α/β against HSV-1. In the absence of RNase L, viral yields were increased 10-fold, but the antiviral effect of IFN was either unaffected or enhanced. These results suggest that the predominant IFN-mediated, antiviral pathway during HSV-1 infection taken by IFN-α/β in L929 cells utilizes PKR.
Murine Cytomegalovirus m02 Gene Family Protects against Natural Killer Cell-Mediated Immune Surveillance
Authors: Oliveira Sofia A. , Park Se-Ho , Lee Peter , Bendelac Albert , Shenk Thomas E.
Published: July 2002

The murine cytomegalovirus m02 gene family encodes putative type I membrane glycoproteins named m02 through m16. A subset of these genes were fused to an epitope tag and cloned into an expression vector. In transfected and murine cytomegalovirus-infected cells, m02, m04, m05, m06, m07, m09, m10, and m12 localized to cytoplasmic structures near the nucleus, whereas m08 and m13 localized to a filamentous structure surrounding the nucleus. Substitution mutants lacking the m02 gene (SM
sub
m02) or the entire m02 gene family (SM
sub
m02-16) grew like their wild-type parent in cultured cells. However, whereas SM
sub
m02 was as pathogenic as the wild-type virus, SM
sub
m02-16 was markedly less virulent. SM
sub
m02-16 produced less infectious virus in most organs compared to wild-type virus in BALB/c and C57BL/6J mice, but it replicated to wild-type levels in the organs of immunodeficient γ
c
/Rag2 mice, lacking multiple cell types including natural killer cells, and in C57BL/6J mice depleted of natural killer cells. These results argue that one or more members of the m02 gene family antagonize natural killer cell-mediated immune surveillance.