bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human Papillomavirus Type 33 E7 Peptides Presented by HLA-DR*0402 to Tumor-Infiltrating T Cells in Cervical Cancer
Authors: Höhn Hanni , Pilch Henryk , Günzel Susanne , Neukirch Claudia , Freitag Kirsten , Necker Antje , Maeurer Markus J. 
Published: July 2002

ABSTRACTSeveral characteristics make human papillomavirus (HPV) amenable to vaccination. Anti-HPV-directed vaccines are based on the observation that HPV E6 and E7 oncoproteins are constitutively expressed in HPV-positive cervical cancer and may serve as tumor rejection antigens. Five HPV types (16, 18, 31, 33, and 45) account for 80% of cervical cancer. Until now, the type of immune response capable of mediating an effective antitumor response has not been defined. In order to define the anticancer-directed immune response in situ, we characterized CD4+and CD8+sorted T cells from peripheral blood lymphocytes, freshly harvested tumor tissue, and tumor-infiltrating lymphocytes (TIL) from a patient with cervical cancer. The HLA-DR-restricted CD4+T-cell receptor VB16-, VA10-, VA21-, and VA22-positive CD4+T-cell line derived from TIL recognizes autologous HLA-DR*0402+(HPV33+) cervical cancer cells, as determined by gamma interferon secretion. Testing of different peptides spanning the E7 gene revealed that the HPV3373–87peptide ASDLRTIQQLLMGTV represents the immunodominant epitope which can also be presented by the DR*0401 allele to TIL. Such major histocompatibility complex class II-presented peptides represent attractive candidates to augment T-cell responses directed against autologous tumor cells.
Simian-Human Immunodeficiency Virus Containing a Human Immunodeficiency Virus Type 1 Subtype-E Envelope Gene: Persistent Infection, CD4
+
T-Cell Depletion, and Mucosal Membrane Transmission in Macaques
Authors: Himathongkham Sunee , Halpin Nancy S. , Li Jinling , Stout Michael W. , Miller Christopher J. , Luciw Paul A. 
Published: July 2002

ABSTRACT

The envelope (
env
) glycoprotein of human immunodeficiency virus type 1 (HIV-1) determines several viral properties (e.g., coreceptor usage, cell tropism, and cytopathicity) and is a major target of antiviral immune responses. Most investigations on
env
have been conducted on subtype-B viral strains, prevalent in North America and Europe. Our study aimed to analyze
env
genes of subtype-E viral strains, prevalent in Asia and Africa, with a nonhuman primate model for lentivirus infection and AIDS. To this end, we constructed a simian immunodeficiency virus/HIV-1 subtype-E (SHIV) recombinant clone by replacing the
env
ectodomain of the SHIV-33 clone with the
env
ectodomain from the subtype-E strain HIV-1
CAR402
, which was isolated from an individual in the Central African Republic. Virus from this recombinant clone, designated SHIV-E-CAR, replicated efficiently in macaque peripheral blood mononuclear cells. Accordingly, juvenile macaques were inoculated with cell-free SHIV-E-CAR by the intravenous or intravaginal route; virus replicated in these animals but did not produce hematological abnormalities. In an attempt to elicit the pathogenic potential of the recombinant clone, we serially passaged this viral clone via transfusion of blood and bone marrow through juvenile macaques to produce SHIV-E-P4 (fourth-passage virus). The serially passaged virus established productive infection and CD4
+
T-cell depletion in juvenile macaques inoculated by either the intravenous or the intravaginal route. Determination of the coreceptor usage of SHIV-E-CAR and serially passaged SHIV-E-P4 indicated that both of these viruses utilized CXCR4 as a coreceptor. In summary, the serially passaged SHIV subtype-E chimeric virus will be important for studies aimed at developing a nonhuman primate model for analyzing the functions of subtype-E
env
genes in viral transmission and pathogenesis and for vaccine challenge experiments with macaques immunized with HIV-1
env
antigens.
Influence of the Theiler's Virus L∗ Protein on Macrophage Infection, Viral Persistence, and Neurovirulence
Authors: van Eyll Olivier , Michiels Thomas 
Published: July 2002

ABSTRACTThe genome of picornaviruses contains a large open reading frame (ORF) translated as a precursor polypeptide that is processed to yield all the proteins necessary for the viral life cycle. In persistent but not in neurovirulent strains of Theiler's virus, an overlapping ORF encodes an additional 18-kDa protein called L∗. We confirmed previous work showing that the L∗ ORF of persistent strains facilitates the infection of macrophage cell lines, and we present evidence that this effect is due to the L∗ protein itself rather than to competition for the translation of the two overlapping ORFs. The introduction of an AUG codon to restore the L∗ ORF of the neurovirulent GDVII strain also enhanced the infection of macrophages, in spite of the divergent evolution of this protein. The presence or the absence of the L∗ AUG initiation codon had only a weak influence on the neurovirulence of the GDVII strain and on the persistence of the DA1 strain. The results obtained with DA1 in vivo contrast with the results reported previously for DAFL3, another molecular clone of the same virus strain, where the AUG-to-ACG mutation of the L∗ initiation codon totally blocked viral persistence (G. D. Ghadge, L. Ma, S. Sato, J. Kim, and R. P. Roos, J. Virol. 72:8605–8612, 1998). Thus, a factor that is critical for the persistence of a given clone of Theiler's virus is dispensable for the persistence of a closely related clone, indicating that different adjustments in the expression of persistence determinants occur in related viral strains.
Rescue of Multiple Viral Functions by a Second-Site Suppressor of a Human Immunodeficiency Virus Type 1 Nucleocapsid Mutation
Authors: Cimarelli Andrea , Sandin Sara , Höglund Stefan , Luban Jeremy 
Published: July 2002

ABSTRACTHuman immunodeficiency type 1 (HIV-1) bearing the nucleocapsid (NC) mutation R10A/K11A is replication defective. After serial passage of the mutant virus in tissue culture, we isolated a revertant that retained the original mutation. It had acquired, in addition, a new mutation (E21K) that was formally demonstrated to be sufficient for restoration of viral replication. Detailed analysis of the replication defect of R10A/K11A revealed a threefold reduction in virion yield and a fivefold reduction in packaging of viral genomic RNA. Real-time PCR was then used to quantitate viral DNA synthesis following infection of Jurkat T cells. After adjustment for the assembly and packaging defects, a minor (twofold) reduction in synthesis of either strong-stop, full-length linear DNA or 2-LTR circles was observed with R10A/K11A virions, indicating that reverse transcription and nuclear transport of the viral genome were largely intact. However, after adjustment for the amounts of full-length or 2-LTR circles produced, R10A/K11A virions were at least 10-fold less infectious than wild type, indicating that viral DNA produced by the R10A/K11A mutant failed to integrate. Each of the above-mentioned defects was corrected by introduction of the second-site compensatory mutation E21K. These results demonstrate that the replication defect of mutant R10A/K11A can be explained by impairment at multiple steps in the viral life cycle, most important among them being integration and RNA packaging. The E21K mutation is predicted to restore positive charge to the face of the R10A/K11A mutant NC protein that interacts with the HIV-1 SL3 RNA stem-loop, emphasizing the importance of NC basic residues for HIV-1 replication.
ATP-Dependent Simian Virus 40 T-Antigen–Hsc70 Complex Formation
Authors: Sullivan Christopher S. , Gilbert Susan P. , Pipas James M. 
Published: July 2002

ABSTRACT
Simian virus 40 large T antigen is a multifunctional oncoprotein that is required for numerous viral functions and the induction of cellular transformation. T antigen contains a J domain that is required for many of its activities including viral DNA replication, transformation, and virion assembly. J-domain-containing proteins interact with Hsc70 (a cellular chaperone) to perform multiple biological activities, usually involving a change in the conformation of target substrates. It is thought that Hsc70 associates with T antigen to assist in performing its numerous activities. However, it is not clear if T antigen binds to Hsc70 directly or induces the binding of Hsc70 to other T-antigen binding proteins such as pRb or p53. In this report, we show that T antigen binds Hsc70 directly with a stoichiometry of 1:1 (dissociation constant = 310 nM Hsc70). Furthermore, the T-antigen–Hsc70 complex formation is dependent upon ATP hydrolysis at the active site of Hsc70 (ATP dissociation constant = 0.16 μM), but T-antigen–Hsc70 complex formation does not require nucleotide hydrolysis at the T-antigen ATP binding site. N136, a J domain-containing fragment of T antigen, does not stably associate with Hsc70 but can form a transient complex as assayed by centrifugation analysis. Finally, T antigen does not associate stably with either of two yeast Hsc70 homologues or an amino-terminal fragment of Hsc70 containing the ATPase domain. These results provide direct evidence that the T-antigen–Hsc70 interaction is specific and that this association requires multiple domains of both T antigen and Hsc70. This is the first demonstration of a nucleotide requirement for the association of T antigen and Hsc70 and lays the foundation for future reconstitution studies of chaperone-dependent tumorigenesis induced by T antigen.
Expression of Major Capsid Protein VP-1 in the Absence of Viral Particles in Thymomas Induced by Murine Polyomavirus
Authors: Sanjuan Norberto , Porrás Analı́a , Otero Javier , Perazzo Sofı́a 
Published: July 2002

ABSTRACT
Thymomas induced by polyomavirus strain PTA in mice are known to express the major capsid protein VP-1. Since the expression of a late structural protein such as VP-1 is considered a sign of virus replication, the present work attempted to clarify the implication of the presence of this protein in tumor cells. Electron microscopy of tumors showed a striking absence of viral particles in the vast majority of the cells. However, immunoelectron microscopy of the same samples demonstrated intranuclear VP-1 in most cells despite the absence of viral particles. Very little infectious virus was recovered from tumors. A change in the electrophoretic mobility of VP-1 from thymomas was detected compared with VP-1 from productively infected cells. The data presented in this work prove that the expression of VP-1 in polyomavirus-induced tumors is not synonymous with the presence of infectious virus, suggesting a possible defect in viral encapsidation.
Downregulation of IRF-3 Levels by Ribozyme Modulates the Profile of IFNA Subtypes Expressed in Infected Human Cells
Authors: Yeow Wen-Shuz , Au Wei-Chun , Lowther William J. , Pitha Paula M. 
Published: July 2002

ABSTRACT
As an early response to viral infection, cells express a number of cellular genes that play a role in innate immunity, including alpha/beta interferons (IFN). IFN-α/β are encoded by a single IFNB gene and multiple, closely related IFNA genes. The induction of these IFN genes in infected cells occurs at the transcriptional level, and two transcription factors of the IRF family, IRF-3 and IRF-7, were shown to play a role in their activation. While the expression of IRF-3 alone was shown to be sufficient for induction of the IFNB gene, induction of all the IFNA subtypes in human cells required the presence of IRF-7. Since IRF-3 is expressed constitutively in all cells examined, the role of IRF-3 in the induction of IFNA genes has not been clarified. Using ribozyme targeted to IRF-3 mRNA, we found that the downregulation of IRF-3 levels in the infected cells inhibited not only the induction of IFNB gene but also the expression of IFNA genes. Furthermore, downmodulation of IRF-3 levels altered the expression profile of IFNA subtypes induced by viral infection. These studies suggest that the ratio between the relative levels of IRF-3 and IRF-7 is a critical determinant for the induction of the individual IFNA subtypes in infected cells.
Inhibitors of Human Immunodeficiency Virus Type 1 Reverse Transcriptase Target Distinct Phases of Early Reverse Transcription
Authors: Hooker C. William , Lott William B. , Harrich David 
Published: July 2002

ABSTRACT
Early HIV-1 reverse transcription can be separated into initiation and elongation phases. Here we show, using PCR analysis of negative-strand strong-stop DNA [(−)ssDNA] synthesis in intact virus, that different reverse transcriptase (RT) inhibitors affect distinct phases of early natural endogenous reverse transcription (NERT). The effects of nevirapine on NERT were consistent with a mechanism of action including both specific and nonspecific binding events. The nonspecific component of this inhibition targeted the elongation reaction, whereas the specific effect seemed principally to be directed at very early events (initiation or the initiation-elongation switch). In contrast, foscarnet and the nucleoside analog ddATP inhibited both early and late (−)ssDNA synthesis in a similar manner. We also examined compounds that targeted other viral proteins and found that Ro24-7429 (a Tat antagonist) and rosmarinic acid (an integrase inhibitor) also directly inhibited RT. Our results indicate that NERT can be used to identify and evaluate compounds that directly target the reverse transcription complex.
Human Papillomavirus Type 6b Virus-Like Particles Are Able To Activate the Ras-MAP Kinase Pathway and Induce Cell Proliferation
Authors: Payne Elizabeth , Bowles Mark R. , Don Alistair , Hancock John F. , McMillan Nigel A. J. 
Published: July 2002

ABSTRACT

The initial step in viral infection is the attachment of the virus to the host cell via an interaction with its receptor. We have previously shown that a receptor for human papillomavirus is the α6 integrin. The α6 integrin is involved in the attachment of epithelial cells with the basement membrane, but recent evidence suggests that ligation of many integrins results in intracellular signaling events that influence cell proliferation. Here we present evidence that exposure of A431 human epithelial cells to human papillomavirus type 6b L1 virus-like particles (VLPs) results in a dose-dependent increase in cell proliferation, as measured by bromodeoxyuridine incorporation. This proliferation is lost if VLPs are first denatured or incubated with a monoclonal antibody against L1 protein. The MEK1 inhibitor PB98059 inhibits the VLP-mediated increase in cell proliferation, suggesting involvement of the Ras-MAP kinase pathway. Indeed, VLP binding results in rapid phosphorylation of the β4 integrin upon tyrosine residues and subsequent recruitment of the adapter protein Shc to β4. Within 30 min, the activation of Ras, Raf, and Erk2 was observed. Finally, the upregulation of c-
myc
mRNA was observed at 60 min. These data indicate that human papillomavirus type 6b is able to signal cells via the Ras-MAP kinase pathway to induce cell proliferation. We hypothesize that such a mechanism would allow papillomaviruses to infect hosts more successfully by increasing the potential pool of cells they are able to infect via the initiation of proliferation in resting keratinocyte stem and suprabasal cells.
Rotavirus Genome Segment 7 (NSP3) Is a Determinant of Extraintestinal Spread in the Neonatal Mouse
Authors: Mossel Eric C. , Ramig Robert F. 
Published: July 2002

ABSTRACT

We used the neonatal mouse model of rotavirus infection to study extraintestinal spread following oral inoculation. Five-day-old pups were inoculated with either SA11-Cl3, SA11-Cl4, SA11-4F, RRV, or B223. By using virus detection in the liver as a proxy determination for extraintestinal spread, rotavirus strains capable of extraintestinal spread at high frequency (rhesus rotavirus [RRV]) and very low frequency (SA11-Cl4) were identified. Both strains productively infected the gastrointestinal tract. Oral inoculation of mice with RRV/ SA11-Cl4 reassortants and determination of virus titers in the gut and liver revealed that the extraintestinal spread phenotype segregated with RRV genome segment 7 to a high level of significance (
P
= 10
−3
). RRV segment 7 also segregated with the growth of virus in the gut (
P
= 10
−5
). Although infection of the gut was clearly required for tropism to the liver, there was no correlation between virus titers in the gut and detection of virus in the liver. Five days after intraperitoneal administration to bypass the gut barrier to virus spread, RRV and SA11-Cl4 both were recovered in the liver. However, only RRV was found in the liver following subcutaneous inoculation, suggesting that this peripheral site presented a similar barrier to virus spread as the gut. Sequence analysis of segment 7 from parental RRV and SA11-Cl4 and selected reassortants showed that (i) amino acid differences were distributed throughout the coding sequences and not concentrated in any particular functional motif and (ii) parental sequence was preserved in reassortants. These data support the hypothesis that NSP3, coded for by genome segment 7, plays a significant role in viral growth in the gut and spread to peripheral sites. The mechanism of NSP3-mediated tropism is under investigation.
Alternative Fates of Keratinocytes Transduced by Human Papillomavirus Type 18 E7 during Squamous Differentiation
Authors: Chien Wei-Ming , Noya Francisco , Benedict-Hamilton Heather M. , Broker Thomas R. , Chow Louise T. 
Published: July 2002

ABSTRACT

The human papillomavirus type 18 (HPV-18) E7 protein promotes S-phase reentry in postmitotic, differentiated keratinocytes in squamous epithelium to facilitate vegetative viral DNA amplification. To examine the nature and fate of the differentiated cells that reenter S phase, organotypic cultures of primary human keratinocytes transduced with HPV-18 E7 were pulse-chase-pulse-labeled with
3
H-thymidine (
3
H-TdR) and bromodeoxyuridine (BrdU). The kinetics of the appearance of doubly labeled suprabasal cells demonstrate that E7 expression did not promote prolonged S phase. Rather, there was a considerable lag before a small percentage of the cells reentered another round of S phase. Fluorescence in situ hybridization analysis, indeed, revealed a small fraction of the cells with more than 4n chromosomes in the differentiated strata. Differentiated cells positive for
3
H-TdR, BrdU, or both often had enlarged nuclei or were binucleated. These results suggest that S phase is not followed by cell division, although nuclear division may occur. Interestingly, a significant fraction of differentiated cells that entered S phase subsequently accumulated p27kip1 protein with a kinetics preceding the accumulation of cyclin E. We conclude that E7-transduced, differentiated keratinocytes that enter S phase have two alternative fates: (i) a low percentage of cells undergoes endoreduplication, achieving higher than 4n ploidy, and (ii) a high percentage of cells accumulates the p27kip1, cyclin E, and p21cip1 proteins, resulting in arrest and preventing further S-phase reentry.
Viable Human Cytomegalovirus Recombinant Virus with an Internal Deletion of the IE2 86 Gene Affects Late Stages of Viral Replication
Authors: Sanchez Veronica , Clark Charles L. , Yen Judy Y. , Dwarakanath Roopashree , Spector Deborah H. 
Published: July 2002

ABSTRACT
Using bacterial artificial chromosome (BAC) technology, we have constructed and characterized a human cytomegalovirus recombinant virus with a mutation in the exon specific for the major immediate-early region 2 (IE2) gene product. The resulting IE2 86-kDa protein (IE2 86) has an internal deletion of amino acids 136 to 290 and is fused at the carboxy terminus to enhanced green fluorescent protein (EGFP). The deletion also removes the promoter and initiator methionine for the p40 form of IE2 and initiator methionine for the p60 form of the protein, and therefore, these late gene products are not produced. The mutant virus IE2 86ΔSX-EGFP is viable but exhibits altered growth characteristics in tissue culture compared with a full-length wild-type (wt) IE2 86-EGFP virus or a revertant virus. When cells are infected with the mutant virus at a low multiplicity of infection (MOI), there is a marked delay in the production of infectious virus. This is associated with slower cell-to-cell spread of the virus. By immunofluorescence and Western blot analyses, we show that the early steps in the replication of the mutant virus are comparable to those for the wt. Although there is significantly less IE2 protein in the cells infected with the mutant, there is only a modest lag in the initial accumulation of IE1 72 and viral early proteins, and viral DNA replication proceeds normally. The mutation also has only a small effect on the synthesis of the viral major capsid protein. The most notable molecular defect in the mutant virus infection is that the steady-state levels of the pp65 (UL83) and pp28 (UL99) matrix proteins are greatly reduced. In the case of UL83, but not UL99, there is also a corresponding decrease in the amount of mRNA present in cells infected with the mutant virus.
Cyclophilin A Plays Distinct Roles in Human Immunodeficiency Virus Type 1 Entry and Postentry Events, as Revealed by Spinoculation
Authors: Saphire Andrew C. S. , Bobardt Michael D. , Gallay Philippe A. 
Published: July 2002

ABSTRACT
Cyclophilin A (CypA) is necessary for effective human immunodeficiency virus type 1 (HIV-1) replication. However, the functions of CypA and the precise steps at which CypA acts in the HIV-1 life cycle remain to be determined. By using a methodology that bypasses the need for attachment factors—spinoculation—we present evidence that CypA participates in both entry and postentry events.
An aggressive intrasinusoidal lymphoma presenting with marked systemic disturbance but normal imaging studies
Authors: Camidge Ross , Ong Edmund , Lucraft Helen 
Published: July 2002

Summary
A patient with an aggressive intrasinusoidal non-Hodgkins lymphoma, presenting with marked systemic disturbance but only a mildly raised alkaline phosphatase as a localising sign is described. All imaging studies of the liver were normal and the diagnosis was delayed until a percutaneous liver biopsy was performed. Once diagnosed, the patient responded extremely well to conventional anti-lymphoma chemotherapy.
Fulminant ischaemic colitis with atypical clinical features complicating sickle cell disease
Authors: Karim A , Ahmed S , Rossoff L J , Siddiqui R , Fuchs A , Multz A S 
Published: July 2002

Abstract
Clinically significant ischaemic bowel injury is an exceedingly rare complication of sickle cell disease. It manifests as acute surgical abdomen and may respond to conservative treatment. An unusual fatal case of ischaemic colitis with minimal abdominal findings in a young male during a sickle cell vaso-occlusive pain crisis is described. This case demonstrates that an acute surgical abdomen should be considered in such patients who fail to respond to conservative management as untreated this condition may be fatal.