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Biomedical subjects

F Rapp

Publications and source records attributed to F Rapp.

At least 55 records · Page 3Linked to original sources
PubMed1984

Herpes simplex virus latency in isolated human neurons.

Herpes simplex virus is most probably maintained in the ganglion neurons of the peripheral nervous system of humans in a latent form that can reactivate to produce recurrent disease. As an approximation of this cell-virus interaction, we have constructed a herpes simplex virus latency in vitro model system using human fetus sensory neurons as the host cell. Human fetus neurons were characterized as neuronal in origin by the detection of the neuropeptide substance P and the neuron-specific plasma membrane A2B5 antigen. Virus latency was established by blocking complete expression of the virus genome by treatment of infected human neurons with a combination of human leukocyte interferon and (E)-5-(2-bromovinyl)-2'-deoxyuridine for 7 days. After removal of inhibitors, virus latency was maintained for at least 9 days. This in vitro model will provide a system to analyze, in a primary human neuron, the state of the herpes simplex virus genome during establishment and maintenance of experimental latency.

Cell Line↗
PubMed1984

Analysis of the herpes simplex virus genome during in vitro latency in human diploid fibroblasts and rat sensory neurons.

We have previously designed in vitro model systems to characterize the herpes simplex virus type 1 (HSV-1) genome during in vitro virus latency. Latency was established by treatment of infected human embryo lung fibroblast (HEL-F) cells or rat fetal neurons with (E)-5-(2-bromovinyl)-2'-deoxyuridine and human leukocyte interferon and was maintained by increasing the incubation temperature after inhibitor removal. Virus was reactivated by reducing the incubation temperature. We have now examined the HSV-1-specific DNA content of latently infected HEL-F cells and rat fetal neurons treated with (E)-5-(2-bromovinyl)-2'-deoxyuridine and human leukocyte interferon and increased temperature. The HEL-F cell population contained, on an average, between 0.25 and 0.5 copies of most, if not all, HSV-1 HindIII and XbaI DNA fragments per haploid cell genome equivalent. In contrast, the latently infected neurons contained, on an average, 8 to 10 copies per haploid cell genome equivalent of most HSV-1 BamHI DNA fragments. There was no detectable alteration in size or molarity of the HSV-1 terminal or junction DNA fragments obtained by HindIII, XbaI, or BamHI digestion of the latently infected neuron or HEL-F cell DNA, as compared with digestion of a reconstruction mixture of purified HSV-1 virion and HEL-F cell DNAs. These data suggest that the predominant form of the HSV-1 genome in either latently infected cell population is nonintegrated, linear, and nonconcatameric.

Animals↗
PubMed1984

Ultrastructural changes during herpes simplex virus type 2 latency and reactivation in vitro.

An in vitro latency system using herpes simplex virus type 2(HSV2)-infected human embryonic lung cells treated with cytosine arabinoside (ara-C) and incubated at 39.5 degrees after drug removal was used to examine the ultrastructure of the infected cells during (i) ara-C treatment, (ii) the latent period after ara-C removal and temperature elevation, and (iii) reactivation after superinfection with human cytomegalovirus. In the presence of ara-C 'empty', nonenveloped, herpesvirus-like particles were observed in nuclei with fragmented chromatin. After removal of ara-C and temperature elevation, no virions were found. At no time during latent infection were complete virions seen. After superinfection with human cytomegalovirus, extensive synthesis of proteins was suggested by a marked proliferation of rough endoplasmic reticulum, polysomes, and Golgi vesicles. This was followed by the appearance of an electron-dense viral matrix in both the nucleus and cytoplasm and by formation of normal nucleocapsids in the nucleus. The nature of the protein(s) required to reactivate HSV2 is unknown but may involve proteins coded by the virus, the host or both.

Cell Nucleus↗
PubMed1984

Current knowledge of mechanisms of viral carcinogenesis.

Retroviruses are RNA-containing viruses using reverse transcriptase to produce DNA copies capable of insertion into host chromosomes. Appropriate genes are required to confer transforming ability to retroviruses. The src gene, a 60,000-dalton protein with protein kinase activity, is required by avian viruses to induce sarcomas. Normal cells have a gene (sarc) similar to the src gene. Retroviruses with oncogenic properties can arise by recombining with genes on the host chromosome. Herpesviruses, adenoviruses, and papovaviruses have transforming properties residing in only a portion of the genome. Probably, only one to two genes are required for transformation, regardless of the complexity of the virus.

Animals↗
PubMed1984

Herpesviruses, lymphocytes, and AIDS.

The acquired immune deficiency syndrome (AIDS) was first reported in the United States in mid-1981. Since that time, it has received widespread attention in the media and has produced an extremely sensitive public health situation. AIDS is a life-threatening condition that is characterized by an acquired defect(s) in the body's natural immunity to disease. Those at greatest risk for contracting the disease include male homosexuals, haemophiliacs, intravenous drug abusers, and children of mothers with AIDS. Recent results from laboratory investigations strongly support the concept that a virus is responsible for the development of AIDS. These observations are leading rapidly to a better understanding of the pathogenesis of the disease, its mode of spread, and how tests might eliminate contaminated blood or blood products.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Maintenance of human cytomegalovirus genome in human diploid fibroblast cells.

Human embryo lung cells pretreated with a combination of human leukocyte interferon and acyclovir were infected with human cytomegalovirus (HCMV) and treated daily for 14 days with the same inhibitor combination. After removal of the inhibitors, the incubation temperature was maintained at either 37 or 40.5 degrees. Incubation of infected cells at 37 degrees after inhibitor removal resulted in progressive virus-specific cytopathology and eventually total destruction of the cell culture. However, HCMV-infected cells incubated at 40.5 degrees after inhibitor removal exhibited little or no virus-induced cytopathology and HCMV remained noninfectious for 8 days. After extended incubation at 40.5 degrees, infectious HCMV was readily detectable even though virus-specific cytopathology was not evident. Reducing the incubation temperature from 40.5 to 37 degrees resulted in stimulation of infectious virus replication and subsequent destruction of the infected cell culture monolayer within 10 days.

Acyclovir↗
PubMed1983

Herpes simplex virus latency and reactivation in isolated rat sensory neurons.

An in vitro herpes simplex virus type 1 (HSV-1) latency model has been established using neurons isolated from dissociated rat fetus sensory ganglia as the host cell. Rat fetal neuron cells were pretreated for 24 hr at 37 degrees with (E)-5-(2-bromovinyl)-2'-deoxyuridine and human leukocyte interferon, infected with HSV-1 (approximately 2.5 plaque-forming units/cell), and treated for 7 days with the same inhibitor combination. Infectious HSV-1 became undetectable 3 days postinfection and remained undetectable during the remainder of the inhibitor treatment. After removal of inhibitors on day 7, infectious virus remained undetectable for 2-7 days; subsequently, virus replication ensued and neuronal cells were destroyed. Incubation of inhibitor-treated, infected neuron cells at 40.5 degrees after removal of inhibitors resulted in extension of the latent period to at least 15 days. HSV-1 was reactivated from latently infected neurons by reducing the incubation temperature from 40.5 to 37 degrees and virus-specific cytopathology was observed in neurons within 96 hr after reducing temperature. This in vitro model system will provide the first system to analyze, in a primary cell type of neuronal origin, the state of the HSV genome during establishment and maintenance of the latent state and during virus reactivation.

Animals↗
PubMed1983

Synergistic antiviral activity of acyclovir and interferon on human cytomegalovirus.

The efficacy of human alpha interferon (IFN-alpha) combined with 9-(2'-hydroxyethoxymethyl)guanine (acyclovir; ACV), (E)-5-(2-bromovinyl)-2'-deoxyuridine, 9-beta-D-arabinofuranosyladenine, or 1-beta-D-arabinofuranosylcytosine on the inhibition of human cytomegalovirus (HCMV) replication in human embryonic lung cells was analyzed by plaque reduction assays. IFN-alpha combined with 9-beta-D-arabinofuranosyladenine or 1-beta-D-arabinofuranosylcytosine produced an additive antiviral activity with respect to HCMV plaque formation. IFN-alpha combined with (E)-5-(2-bromovinyl)-2'-deoxyuridine also exhibited additive antiviral activity. However, IFN-alpha combined with ACV at concentrations higher than 10 microM consistently yielded synergistic activity in HCMV plaque reduction assays. Kinetic analyses of HCMV replication demonstrated that approximately a 1,000-fold reduction can be attained through the synergistic interaction between ACV (200 microM) and IFN-alpha (42 IU/ml). These data suggest that combined ACV and IFN-alpha treatment may be useful against HCMV infection.

Acyclovir↗
PubMed1983

Hepatic infection by thymidine kinase-positive and thymidine kinase-negative herpes simplex virus after partial hepatectomy.

Herpes simplex virus (HSV) infection of mouse liver after partial hepatectomy was studied. Partial hepatectomy resulted in the rapid onset of cellular DNA synthesis and the appearance of many mitotic figures (peak, 3 days after surgery). Similar changes were not seen in control animals. After partial hepatectomy, the mice were infected with thymidine kinase-positive (TK+) and -negative (TK-) HSV to investigate virus titers in liver tissue during liver cell replication. In control unoperated mice, liver titers of TK+ HSV (2 X 10(3) PFU/g) were greater than those of mice inoculated with TK HSV (4 X 10(1) to 5 X 10(2) PFU/g). After partial hepatectomy, TK+ and TK- HSV titers increased, and peak TK+ and TK- HSV titers were similar (6 X 10(5) to 8 X 10(5) PFU/g). Hepatic infection was further investigated by infectious center (IC) assays. The numbers of ICs for TK+ HSV increased 50-fold after partial hepatectomy, whereas the increase was less for TK- HSV. From the results of these studies, we hypothesize that the increase in hepatic TK+ HSV after hepatectomy may have been largely due to the increase in ICs, whereas the increase in hepatic TK- HSV was due, in part, to the increase in ICs, but may also have been due to the enhanced synthesis of TK- HSV in replicating liver cells.

Animals↗
PubMed1983

Simian virus 40 promoters direct expression of the tetracycline gene in plasmid pACYC184.

Insertion of HindIII DNA fragments into the HindIII site of plasmid pACYC184 destroys the promoter of the plasmid tetracycline resistance gene and causes Escherichia coli cells harboring recombinant plasmids to be tetracycline sensitive and chloramphenicol resistant. The HindIII-C DNA fragment of simian virus 40 contains the two virus promoters and the virus origin of replication. We report the isolation of recombinant plasmids that contained the simian virus 40 HindIII-C DNA fragment at the HindIII site but were capable of conferring tetracycline resistance to E. coli cells. The viral promoter sequences contained in the HindIII-C fragment presumably replaced the inactivated tetracycline resistance gene promoter sequences and enabled transcription of the tetracycline resistance gene.

DNA Restriction Enzymes↗
PubMed1983

Herpesvirus RNA in human urogenital tumors.

In situ hybridization was used to examine human urogenital cancers for herpes simplex virus type 2 (HSV-2) and human cytomegalovirus RNAs. Neither of these herpes RNAs was found in prostate tissues. However, HSV-2 RNA was detected in premalignant and malignant cervical tissues.

Cytomegalovirus↗
PubMed1983

Defective cell-mediated immune response in spontaneous diabetes mellitus in the guinea pig.

The proliferative responses of splenic lymphocytes from spontaneously diabetic, recovered and normal guinea pigs were compared after in vitro stimulation with two different T cell mitogens--PHA and Con-A. The in vitro lymphocyte responses were significantly depressed in diabetic guinea pigs as compared to normal controls. On remission of hyperglycemia, the proliferative responses of lymphocytes returned to normal or to above normal levels. The implication of such a defect in cellular immunity in diabetes is discussed. The guinea pig model of spontaneous diabetes mellitus may be useful for studies on immune competence in juvenile diabetes.

Animals↗