摘要:

The effects of infection by the human cytomegaloviruses Ad-169 on the incorporation of [14C] acetate into the polar and neutral lipids of human embryonic lung cells and human saphenous vein smooth muscle cells were compared to [14C]acetate incorporation in mock-infected control cells. Cytomegalovirus infection caused a shift in the relative amounts of polar and neutral lipids, with infected cells having lower amounts of polar lipids and higher amounts of neutral lipids than mock-infected controls. When neutral lipids were separated into diglyceride (DG), cholesterol (C), fatty acid, triglyceride (TG) and cholesterol ester (CE) components, Ad-169-infected cells had lower levels of incorporation of label into CE, TG, and DG fractions, and higher levels of label incorporation into C than mock-infected cells.

ISSN:0300-5526    

DOI:10.1159/000150521

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The close association of Epstein-Barr virus (EBV) and nasopharyngeal carcinoma (NPC) is well documented and the expression of EBV-related latent genes has been shown in NPC. Nevertheless, the status of EBV infection in the nontumor epithelial and lymphoid cells is not known. In this study, we detected EBV in the nontumor component of NPC and nontumor nasopharyngeal biopsies by in situ hybridization using digoxigenin-labeled antisense EBER1 oligoprobe in 346 nasopharyngeal biopsies. Latent membrane protein (LMP) and ZEBRA were detected by immunohistochemistry in cases containing EBER1-positive cells. The EBV-positive epithelial and lymphoid cells were identified by immunostains for cytokeratin and lymphoid phenotypes. In the nontumor nasopharyngeal biopsies, 21 (11.7%) of 179 cases had EBV-harboring lymphocytes in the lymphoid tissue, while the overlying mucosa was all negative. LMP was demonstrated in lymphoid cells of 14 (66.7%) of these 21 samples. These EBV-positive lyphocytes were B lymphocytes by combined phenotype study. EBER1-containing metaplastic squamous cells were demonstrated in the overlying mucosa close to the tumor tissue in 14 (8.4%) of 167 NPC samples. In contrast, the respiratory epithelial cells in these cases were all negative. Two (1.2%) of these cases had EBV-positive lymphocytes in the lymphoid stroma. Four of the 346 cases had ZEBRA-positive cells. This study demonstrated that latent infection and, occasionally, active replication of EBV were present in stromal B lymphocytes in nasopharyngeal tissue with and without NPC. EBER1 was found only in the metaplastic squamous cells in the mucosa of nasopharyngeal tissues with NPC, but not in those without NPC.

ISSN:0300-5526    

DOI:10.1159/000150522

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The process of transcriptional activation directed by the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) was investigated by in vivo footprinting using ligation-mediated polymerase chain reaction in a human epithelial cell line infected with human herpes simplex virus type 1 (HSV-1) or human herpes virus 6 (HHV-6). Infection with both viruses induces a remarkable enhancement in LTR-mediated gene expression that correlates with a change in the pattern of protein binding to the downstream kB site of the enhancer region. In HHV-6 infected cells, this change in the genomic footprinting pattern is concomitant with the induction of specific enhancer-binding proteins in the nucleus. The similarity of these events to those detected in other previously investigated experimental systems suggests that the LTR enhancer region is the ultimate target for the induction of the HIV-1 transcriptional response upon stimuli acting through different upstream pathways.

ISSN:0300-5526    

DOI:10.1159/000150523

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein was expressed by a vaccinia vector that encodes the late promotor P11. The envelope protein synthesized mediated syncytia formation with SupT1 cells and was efficiently cleaved to produce mature gp120 and gp41 in CV-1 cells. gp160 precursor processing was neither affected by a change in culture medium nor by a heterologous vesicular stomatitis virus coinfection. These results suggest that the proteolytic cleavage of gp160 is an efficient process and that coinfection with other viruses may not affect precursor processing of the HIV-1 Env protein.

ISSN:0300-5526    

DOI:10.1159/000150524

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

An in vitro cleavage system was established to measure HCV NS3 protease trans-processing activity. This system utilizes purified NS3-4A protein from baculovirus, purified substrates expressed by in vitro transcription and translation and defined buffer components. The 41-residue substrates, 5A/5B and 4A/4B, were processed efficiently in trans by wild-type NS3 but not by a catalytically inactive mutant protease; radiolabel sequencing confirmed that NS3-mediated cleavage occurred at the correct cysteine/serine sites, thereby authenticating this system. Two striking features of this in vitro assay are: (1) analogous 4B/5A and 3/4A substrates cannot be processed in trans under the same conditions, and (2) in vitro cleavage of the 5A/5B and 4A/4B sites is highly dependent on the presence of NS4A, which we show is not the case in vivo.

ISSN:0300-5526    

DOI:10.1159/000150525

出版商:S. Karger AG    

年代:1996

数据来源: Karger

ISSN:0300-5526    

DOI:10.1159/000150526

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Although there is no definitive evidence of the association of human cytomegalovirus (HCMV) infection with human cancers, the oncogenic potential of HCMV has been well established by in vitro studies demonstrating the ability of UV-irradiated or infectious virus to transform a variety of cells. After prolonged passaging the transformed cell type was maintained while HCMV DNA sequences were no more detectable. Three morphological transforming regions (mtr) of HCMV have been identified. The effects of HCMV on cellular functions which may be associated with the malignant phenotype include the expression of oncogenes and transcriptional activation of growth factors and interleukin synthesis. In infected cells, HCMV induces cytoskeletal alterations and changes in expression of cell surface receptors for extracellular matrix proteins which could result in increased motility and dissemination of cancer cells. Several human neuroblastoma cell lines undergo maturation in different neural crest derived cell types upon treatment with oncogenic potential agents, i. e. retinoic acid. The persistent HCMV infection of neuroblastoma cells (>1 year) is accompanied by the increased expression of oncoproteins (i.e. N-myc) and decreased expression of tyrosine hydroxylase and dopamine-β-hydroxylase. The activation of the cellular metabolism is due to HCMV binding to cellular receptors (prior to virus gene expression) and to the activity of HCMV immediate early (IE) gene products. IE proteins act directly as transcriptional activators or their activity is mediated by a variety of cellular transcription factors. HCMV infection may result in activation of promoters of cellular genes coding for cytokines, replication enzymes, protooncogenes and viral promoters. Recently it has been demonstrated that HCMV IE proteins block apoptosis probably by suppressing the ability of the antioncogene p53 to activate a reporter gene. The interactions of HCMV with tumor suppressor proteins such as p53 or retinoblastoma (pRb) susceptibility protein are reminiscent of those mediated by the oncoproteins of DNA tumor viruses. The acquisition of a fully malignant phenotype by normal cells is thought to require several mutations in a number of cellular genes. In this connection, HCMV may play the role of a nonobligate either direct or indirect cofactor for tumor genesis, e.g. by blocking apoptosis, which may be an essential requirement for tumor progression. Due to the stimulation of growth factors and/or inhibition of antioncogenes by its gene products, HCMV may modulate the malignant potential of tumor cells

ISSN:0300-5526    

DOI:10.1159/000150527

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The Epstein-Barr virus (EBV) BXLF1 fragment open reading frame (LORF), thought to encode deoxythymidine kinase (dTK) activity, and a shorter frame (SORF), starting at an internal in-frame AUG, were isolated by polymerase chain reaction from a plasmid containing the EcoR1 fragment of EBV strain FF-41. These were transfected into dTK–Escherichia coli, producing multiple SORF- or LORF-containing colonies, which expressed dTK. The 243 NH2 terminal residues of the LORF-encoded polypeptide thus are not essential for dTK activity. SORF, with 1,092 bp, is predicted to encode a 36- to 37-kD polypeptide, in the size range of other herpesviral dTK

ISSN:0300-5526    

DOI:10.1159/000150528

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Restriction endonuclease site maps were constructed for the genome of a caprine adenovirus (GAdV), strain NC90-7261, which was isolated in 1990 from a 3-year-old goat with encephalitis. Genomic GAdV DNA was digested with seven restriction endonucleases (RE). Genomic DNA libraries of GAdV were constructed by cloning BamRl and Hindïíl restriction fragments into a plasmid vector. Using cloned GAdV genomic fragments as probes in Southern blot hybridizations, an RE site map was constructed. The position of several clones was confirmed by limited nucleotide sequencing and the location of several RE sites was determined by single or double RE digestions of cloned fragments. The size of the GAdV genome was determined to be 28.2 kbp. The restriction pattern described in this report is different from that of other adenovimses. Although the genomic organization of this GAdV is likely to be similar to that of other adenoviruses, the overall level of sequence similarity is lo

ISSN:0300-5526    

DOI:10.1159/000150529

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Virus-associated DNA polymerase activity has recently been proposed for the detection of human cytomegalovirus (HCMV) in urine, a method that should allow rapid and quantitative determination of the viral load. In this report, the virus-associated DNA polymerase activity recovered from the urine of a group of patients shedding HCMV was measured using a poly(dA) oligo(dT)12-18 synthetic template after polyethylene glycol precipitation of the virions. Detection of virus-associated DNA polymerase activity was compared to the classical methods most widely used to diagnose HCMV shedding in urines, such as virus culture followed by indirect immunofluorescence and pp65 gene-specific polymerase chain reaction. Although less sensitive than the polymerase chain reaction and cross-reactive with other herpesvirus DNA polymerases, the activity measured in the urine samples was correlated with the number of positive nuclei found in shell vials (r = 0.89). The diagnostic threshold of the assay could be placed between 50 and 100 fluorescent nuclei per shell with a diagnostic sensitivity of 56%. Being simple and quantitative, the measurement of virus-associated DNA polymerase activity could be of value in some clinical conditions where it is necessary to assess viral load in urine. This method is proposed as an alternative to more laborious quantitative assays and to support qualitative polymerase chain reaction.

ISSN:0300-5526    

DOI:10.1159/000150530

出版商:S. Karger AG    

年代:1996

数据来源: Karger