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At least 1,117 records · Page 62Linked to original sources
PubMed1983

Transient rescue of Sendai-6/94 cl virus from the persistently infected cell line Cl-E-8 by cocultivation.

The cell line Cl-E-8 showing expression of Sendai-6/94 viral antigens after the original isolation was reexamined after approximately 160 subcultures. In the virus fraction of cell supernatants 6/94 virus particles (termed 6/94 cl) could be demonstrated; no infectivity, however, was monitored. We were also unable to activate the viral infectivity of 6/94 cl virus by trypsin treatment. The analysis of viral RNA revealed that the virus contains a high-molecular-weight (50 S) single-stranded RNA. After cocultivation of Cl-E-8 cells with several standard cell lines the production of an infectious 6/94 virus, termed 6/94 co, was detected. The infectivity titer in the supernatants was very low, about three orders of magnitude lower than in cultures infected with the egg-grown 6/94 virus (6/94 ST). Surprisingly, the production of infectious 6/94 cl virus invariably ceased several subcultures after cocultivation even in the presence of foreign cells. However, the infectivity could be repeatedly reinduced by adding fresh foreign cells.

Antigens, Viral↗
PubMed1988

Regional localization of virus in the central nervous system of mice persistently infected with murine coronavirus JHM.

Suckling C57BL/6 mice infected with mouse hepatitis virus strain JHM (MHV-JHM) develop either a fatal acute encephalomyelitis or a late onset demyelinating disease, depending on whether they are nursed by unimmunized or immunized dams. To determine the localization of virus-specific RNA, serial sections of brains from infected and uninfected mice were annealed with a 35S-labeled antisense RNA probe and analyzed by film autoradiography. In the mice with acute encephalomyelitis, viral RNA was present in the mesencephalon, hypothalamus, hippocampus, basal ganglia, subcortical white matter, and thalamus. Viral RNA was detected in the spinal cords of all mice with the late onset, demyelinating encephalomyelitis, but was distributed into three different patterns in the brains of these mice, even though all had the same clinical disease. In the first group, viral RNA was detected only in the brainstem. In the second group, viral RNA was detected in the brainstem, thalamus, and cerebral grey matter. This distribution was consistent with viral spread along well-defined tracts connecting these parts of the brain. In the third group, viral RNA could be detected both in the brainstem and in several white matter tracts within close physical proximity to the optic chiasm. This distribution was consistent with viral spread by an extracellular route from one white matter tract to other tracts which were physically close, but which were not part of the same pathways. These results suggest that MHV-JHM spreads through the central nervous system both along well-defined neuronal pathways and by spread from contiguous structures, but also suggest that viral replicates preferentially in a limited number of areas of the brain. The technique of in situ hybridization with film autoradiography should be generally useful for analyzing macroscopic movements of virus within infected organs.

Animals↗
PubMed1986

Sendai virus replication in Friend erythroleukemia cells. I. Acutely and persistently infected cells become resistant to virus-induced lysis.

Friend leukemia cells (FLC) are susceptible to infection by Sendai virus, a member of the paramyxovirus group. FLC constitute a most suitable model to study virus-host cell interactions, because they grow in suspension (thus avoiding the use of trypsin), and provide an easy way of deriving single-cell clones. When FLC are infected with Sendai virus at high m.o.i., a direct, extensive lysis of the cells ensues, whereas lower doses of virus result in a cytocidal infection whose lethality depends mainly on the virus used, standard or defective interfering egg-grown Sendai virus (EGSV), and on the multiplicity of infection (m.o.i). At later times after infection, FLC become resistant to the Sendai induced lysis (SIL). The SIL resistance can be maintained in single-cell clones that had survived the first infection. The maintenance of the resistant phenotype of the clones requires the serial subcultivation of the cells in the presence of activated EGSV. The mechanisms that presumably regulate the appearance of SIL resistance in Sendai infected FLC are discussed.

Cell Fusion↗
PubMed1989

Persistent infection of mice by lactate dehydrogenase-elevating virus: transient virus replication in macrophages of the spleen.

In order to assess whether the spleen is the major site of replication of lactate dehydrogenase-elevating virus (LDV) in mice during the acute phase of infection, LDV replication in the spleen was measured by electron microscopy and fluorescent antibody staining of tissue sections and northern hybridization of total spleen RNA with an LDV-specific cDNA probe, and the effect of splenectomy on LDV replication was determined. LDV RNA and antigens and infected cells, presumably macrophages, were present in the spleen in high concentrations 18-25 h post infection, but then rapidly disappeared to undetectable levels during the next 1-2 days. Thus, LDV clearly replicates in the spleen during the initial phase of infection, but LDV replication in the spleen is transient due to the cytocidal nature of LDV replication and destruction of all permissive macrophages in the spleen. Furthermore, spleen macrophages do not seem to represent the major source of LDV released into the circulation, since LDV viremia as well as anti-LDV antibody production were the same in splenectomized and control animals for at least 28 days postinfection.

Animals↗
PubMed1993

Tumor necrosis factor-alpha induces circular forms of human immunodeficiency virus type-1 DNA in the persistently infected low-level expressing cell line, ACH-2.

The low human immunodeficiency virus type-1 (HIV-1) expressing T-cell line, ACH-2, was used to investigate accumulation of the circular, extrachromosomal form of HIV DNA (HD) after tumor necrosis factor-alpha (TNF-alpha) induction. We chose the 2 long terminal repeat (LTR) circular form to analyze unintegrated HD by polymerase chain reaction (PCR), using primer pairs which flank the 2 LTR HD. Approximately a 10-fold increase in 2 LTR HD was detected intracellularly in the TNF-alpha-induced ACH-2 cells using an end point-dilution assay. To examine the cellular compartment location of the 2 LTR HD accumulation, ACH-2 cells were fractionated into cytoplasmic and nuclear components and further subjected to PCR. A 4- to 5-fold increase in the 2 LTR HD signal was observed in the nuclear fraction. These results indicate that unintegrated HD increases in a chronically infected cell line after TNF-alpha induction. This phenomenon, which previously had been observed only with acute infections, may offer insight into basic pathogenic mechanisms.

Cell Line↗
PubMed1986

Hypothesis: AIDS encephalopathy is due to primary and persistent infection of the brain with a human retrovirus of the lentivirus subfamily.

Recent evidence has demonstrated that human T-lymphotropic retroviruses are present in the brain of patients with acquired immunodeficiency syndrome (AIDS). Studies by neuropathological, ultrastructural and nucleic acid hybridization techniques indicate that these human retroviruses are neurotropic as well as lymphotropic. Striking similarities to the animal retroviruses of the lentivirus subfamily provide a rationale to implicate these human retroviruses (lentiviruses) in the pathogenesis of AIDS encephalopathy.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Flavobacterium meningosepticum bacteremia in an adult with acute leukemia. Use of rifampin to clear persistent infection.

A case of Flavobacterium meningosepticum bacteremia complicating the course of a patient with leukemia is described. The patient was treated successfully when rifampin was added to the antibiotic therapy. Unusual organisms should be considered as agents of infection in immunocompromised hosts and susceptibility testing with drugs not commonly employed for gram-negative rods should be performed in complicated cases.

Acute Disease↗
PubMed1999

Testicular sperm aspiration and intracytoplasmic sperm injection for persistent infection of the ejaculate.

OBJECTIVE: To report the successful use of testicular sperm aspiration and intracytoplasmic sperm injection in the presence of an Escherichia coli-infected ejaculate that previously caused repeated embryo degeneration. DESIGN: Case report. SETTING: University medical center. PATIENT(S): A 38-year-old woman who did not conceive for 6 years with repeated IVF attempts. Escherichia coli was isolated from both the oocyte culture dish and her male partner's ejaculate. INTERVENTION(S): Testicular sperm aspiration and intracytoplasmic sperm injection followed by ET. MAIN OUTCOME MEASURE(S): Clinical outcome. RESULT(S): Establishment of a pregnancy delivered at term. CONCLUSION(S): Patients undergoing IVF treatment who have repeated embryo degeneration caused by bacterial infection originating in the ejaculate may be treated successfully with testicular sperm aspiration and intracytoplasmic sperm injection.

Adult↗