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At least 559 records · Page 31Linked to original sources
PubMed1975

A quantitative comparison between in vivo-and in vitro-derived Friend leukemia virus.

The biological activities of RNA viruses derived from Friend leukemia cells in culture (TCV) were compared with those of viruses derived from the plasma (PV) of mice infected with Friend leukemia virus (FLV). The comparison was quantitatively based on the actual number of viruses used in each experiment as determined by counting under the electron microscope. Electron microscopy also provided a qualitative assessment of the structural integrity of the concentrated virus particles used in various bioassays. The data shows that the leukemogenic and spleen-focus-forming (SFF) activities of TCV, although demonstrable, are respectively 10(5) and 10(4) lower than those of PV. Moreover, TCV has 10(4) less helper activity (S+L- test) than PV. The level of reverse transcriptase activity is ten times lower in TCV than in PV which indicates that there is little correlation between polymerase activity and the other biological activities measured. The decreased biological activity of the in vitro grown virus is thought to be intrinsic to this type of virus although all extrinsic factors have not been ruled out.

Animals↗
PubMed1976

Survey of human lymphoblastoid cell lines and primary cultures of normal and leukaemic leukocytes for oncornavirus production.

Velocity sedimentation of uridine-labelled cultures was found to be more reliable than isopycnic sedimentation in detecting oncornavirus production in lymphoid cells. Of 13 cell lines (including six derivea from Burkitt's lymphomas and two from leukaemic leukocytes) only one, the leukaemia-derived, Epstein-Barr virus-producing line QIMR-WIL, showed any activity. The nature of the QIMR-WIL particles was further defined by isolation of uridine-labelled 70S RNA and by the simultaneous assay for reverse transcriptase and 70S RNA, but production of such particles was detected in only three of 10 assays. Pretreatment of cells with 5'-iododeoxyuridine or culture in arginine-free medium did not induce particle production. Syncytia assays using XC cells were negative. Of 13 primary cultures (nine samples of leukaemic leukocytes and four of cord leukocytes) treated with mitogens and subjected to inducing conditions, one (leukocytes from a patient with acute myelogenous leukaemia) showed evidence in successive assays of oncornavirus synthesis. The low and transient yield of oncornavirus-like particles obtained in this work parallels that reported in previous studies of fresh lymphoid cells and primary cultures.

Burkitt Lymphoma↗
PubMed2001

Mosquito cells bind and replicate hepatitis C virus.

Several studies have demonstrated some hepatitis C virus (HCV) replication in lymphocyte and hepatocyte cell lines such as in African green monkey Vero cells. The aim of the present study was to select other cell lines able to bind and replicate HCV. Human hepatoma PLC/PRF/5 cells, human lymphoma Namalwa cells, Vero and mosquito AP61 cells were inoculated with HCV-positive plasma, washed six times and examined for the presence of the viral genome at different times post infection, using an RT-PCR method. Binding of HCV to cells was estimated by HCV RNA detection in cells 2 hr after inoculation and in the last wash of these cells. Successive virus passages in cells were carried out. All the cells studied were able to bind HCV but only AP61 and Vero cells provided evidence of replication and production of infectious virus: virus RNA was detected during 28 days post-infection in four successive virus passages. CD81 molecules, a putative HCV receptor, were detected by cytofluorometric analysis. Vero cells express CD81 molecules whereas these molecules were not detected on AP61 cells. It is suggested that other receptors are involved in HCV binding to Vero and AP61 cells.

Adult↗
PubMed2003

Comparative study of enterovirus 71 infection of human cell lines.

The cell tropism of enterovirus 71 (Enteroviridae) in neuronal, glial and laryngeal cells. The 4643 strain, an enterovirus 71 isolate from a patient in Taiwan, was used to infect three human cell lines representing neuronal cells (SK-N-SH, neuroblastoma), glial cells (U373MG, glioblastoma), and laryngeal cells (HEp-2, larynx epidermoid carcinoma). Immunofluorescent staining and transmission electron microscopy (TEM) were used to detect mature enterovirus 71 4643 virions in these cell lines. The three cell lines were also compared for presence of virus-mediated cytopathic effect (CPE), synthesis of infected cell-specific proteins, viral (-) RNA, and virus replication rate. Virus particles were detected by TEM, and viral replication increased over time, indicating the existence and release of mature viruses from all three infected cell lines. The most severe CPE and the highest viral replication rate were observed in the SK-N-SH cells. Further screening of the infected cell lines by microarray analysis revealed that the neuron growth factor receptor (NGFR) gene was uniquely upregulated in infected SK-N-SH cells, implying that the receptor encoded by this gene may be involved in cell tropism. The data show that neurons are vulnerable to enterovirus 71 4643 infection and are consistent with the clinical observation that enterovirus 71 4643 targets mainly neuronal cells but is also found in many organs in conjunction with an inflammatory reaction.

Animals↗
PubMed1979

Evaluation of Aedes albopictus tissue culture for use in association with arbovirus isolation.

The susceptibility and sensitivity of Aedes albopictus cell cultures to five different primary and four different low-passage arboviruses were tested. Yellow fever, West Nile, Ilesha, eastern equine encephalitis, and Flanders viruses replicated in A albopictus tissue cultures. Replication was determined by the ability of selected tissue culture fluids to infect suckling mice, and by recovery from tissue culture fluid of progressively increasing amounts of complement-fixing (CF) antigen with time. Virus persistence was demonstrated with Nodamura, western equine encephalitis, and Mayaro viruses, but multiplication was not proven; neither persistence nor multiplication was demonstrated with a Kemerovo group virus. When yellow fever and Ilesha viruses were simultaneously inoculated into A albopictus culture, CF antigen for each was consistently detected. In a more detailed comparative study of field specimens, 12 unpassaged strains of yellow fever virus were tested for infectivity in A albopictus tissue culture, Vero cells, and baby mice. Higher titers of virus were detected (0.8--2.3 log ID50 per ml) in Vero cell culture than in A albopictus tissue culture or baby mouse systems. These results suggest the feasibility of using A albopictus cells in association with the primary isolation of arboviruses.

Aedes↗
PubMed1981

Replication of human syncytium-forming virus in human cells: effect of certain biological factors and selective chemicals.

The growth characteristics of the human syncytium-forming virus (HSFV) were examined in several human cell lines of normal and malignant origins and composing of either fibroblastic or epithelial-like cells. Virus production occurred only in the fibroblastic diploid cell lines: HEF (human embryonic cells, Flow #5,000) and HFDL #645 (human fetal diploid lung), but not in the epithelial-like heteroploid cell lines: RA (a continuous line of human amnion), #999 (human bone marrow), and KB (carcinoma of the nasopharynx). While the single-cycle growth pattern of the virus in HEF and HFDL #645 cell lines were essentially similar, the virus yield per cell was greater in the HFDL #645 cells. Furthermore, the physiological state of the cell had a marked effect on virus production. Subconfluent actively growing HFDL #645 cells produced higher yields of virus than density-inhibited confluent HFDL #645 cell cultures. The replication of HSFV was inhibited by actinomycin D at concentrations that did not interfere with poliovirus replication (0.001 to 0.01 microgram/ml). Pretreatment and posttreatments of infected cell cultures with either the polycation polybrene (hexadimethrine bromide) or the synthetic glucocorticosteroid dexamethasone did not enhance HSFV production.

Cell Division↗
PubMed1984

Human spumavirus replication in human cells.

It was previously reported that the replication of the human syncytium-forming virus (HSFV), a spumavirus, occurred only in fibroblast-like cell lines (human fetal diploid lung #645 [HFDL]) but not in epithelial-like lines (recovered amnion) [RA]. Factors that may be involved in such a phenomenon were the subject of this investigation. While both permissive (HFDL) and nonpermissive (RA) cell lines supported the replication of several representative animal viruses and adsorbed HSFV equally well, immunofluorescent staining of HSFV antigens revealed markedly fewer fluorescing cells in nonpermissive cultures. Infectious center assays of infected nonpermissive cells indicated the formation of significantly fewer infectious centers. The rate of DNA synthesis was markedly greater in the permissive cell lines. In addition, in the permissive cell line, the amount of proviral DNA revealed by the Hirt procedure and isopycnic banding in CsCl was significantly increased and was infectious as determined by the calcium phosphate-DMSO transfection assay. These results indicate that resistance of HSFV infection in nonpermissive cell cultures is probably an intracellular event.

Amnion↗
PubMed1985

Immunostimulatory function of herpes simplex virus isolates from patients with frequent herpes labialis and a deficiency in immune-specific interferon production.

Approximately 30% of persons with frequent episodes of herpes labialis are deficient in the production of HSV-induced immune-specific interferon (IFN) (Green, 1985). Herpes simplex virus (HSV) strains isolated from persons who make immune-specific IFN and from persons who do not make it were examined for their immunostimulatory capabilities. HSV isolated from the primary oral lesions of two patients deficient in immune-specific IFN production, one person with an intact immune-specific IFN response, HSV types 1 and 2 laboratory strains, and Newcastle disease virus (NDV) were added to cultures of peripheral blood mononuclear cells (PBML) from HSV seropositive donors. All HSV-isolates induced comparable titers of immune-specific IFN. These studies suggest that failure of some patients to develop an immune-specific IFN response is determined by the host, not the virus.

Animals↗
PubMed1990

Antiviral strategies in chronic hepatitis B virus infection: I. Establishment of an in vitro system using the duck hepatitis B virus model.

Primary duck hepatocyte (PDH) cultures were established from ducklings congenitally infected with the duck hepatitis B virus (DHBV), plated onto feeder cell layers of irradiated human embryonic lung fibroblasts, and observed for 2 to 3 weeks. This system permitted the survival of the PDH in a differentiated form free of fibroblastic overgrowth for at least 3 weeks. The hepatocytes were shown to contain all the replicative DNA intermediates found during DHBV replication as well as the DHBV structural proteins PRE-S1, PRE-S2, and S of duck hepatitis B surface antigen (DHBsAg). The pool of supercoiled (SC) DHBV DNA increased dramatically from days 10 to 14 postplating. This PDH-feeder cell layer cell culture model provides a convenient system to study the effects of conventional inhibitors of DHBV replication and compounds targeted at the supercoiled form of DHBV DNA. This approach should allow the evaluation of a variety of strategies for treating chronic carriers of hepadnaviruses.

Animals↗
PubMed1993

Comparative study of human and rabbit cell infection with cell-free HTLV-I.

Infection of human and rabbit cells with cell-free HTLV-I was studied by PCR analysis. Both human and rabbit PBL were infected similarly by cell-free virus of both human and rabbit cell origin. Cells were infected with the cell-free virus without prior treatment and regardless of the concentration of the culture supernatant containing the virus. Human and rabbit cell lines were also infected similarly by the cell-free virus, the proviral DNA persisting for more than two months. The culture supernatants of HTLV-I-producing cells could thus be a potential cause of laboratory infections.

Animals↗