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Biomedical subjects

F Rapp

Publications and source records attributed to F Rapp.

At least 91 records · Page 5Linked to original sources
PubMed1981

Evolution of a human cell line persistently infected with measles virus.

A measles-virus-carrier cell line, designated AV3/MV, was derived from established human amnion (AV3) cells surviving primary infection with the Edmonston strain of measles virus. During maintenance of infected cultures in the laboratory, the cells passed from a highly productive chronic phase (where infectious virus was continuously shed) to a less productive degenerative phase (where fewer infectious particles were produced). Carrier cultures in the less-productive phase gradually deteriorated and failed to survive at 37 degrees. However, when temporarily maintained and passaged at 39.5 degrees, the cultures stabilized and carried the virus in a latent or nonproductive state. Carrier cultures in the chronic phase of infection expressed variable degrees of virus-specific CPE, replicated erratically, and generated large amounts of virus-specific antigens. In the stabilized latent phase, the cultures demonstrated no virus-specific CPE, replicated steadily, and generated reduced amounts of virus-specific antigens. The results of our studies indicate that the establishment and maintenance of persistent measles virus infections in AV3 cells are dynamic processes involving numerous variables, and that there are similarities between these latent-carrier cell lines and certain virus-carrier cell lines derived from subacute sclerosing panencephalitis brain tissues.

Amnion↗
PubMed1981

Characterization of nonmeasles paramyxovirus isolates from a patient with subacute sclerosing panencephalitis.

Two paramyxovirus isolates recovered from the peripheral blood leukocytes of a patient with subacute sclerosing panencephalitis were characterized by biological, immunological, and molecular techniques. Both virus isolates possessed neuraminidase activity but demonstrated reduced hemagglutination potential. Neutralization titrations showed that the viruses were clearly related to, but were distinct from, simian virus 5. Characterization of purified virus preparations by SDS-PAGE showed that the structural polypeptides of the viruses were similar to those of simian virus 5, but distinct differences were noted as well. In addition, the virus isolates were found to differ from one another, particularly with regard to the major putative transcriptase protein (L).

Adolescent↗
PubMed1981

Interferon induction by measles virus.

Interferon induction in BSC-1 cells by measles virus isolates previously found to be interferon inducing (IF+) or interferon noninducing (IF-) was studied in different cell types. Lack of induction by the IF- viruses was not due to an inhibitory factor since BSC-1 cells coinfected with IF+ and IF- stocks produced interferon levels similar to those infected with IF+ stocks alone. Various tests indicated that the phenotypic expression of interferon induction by these isolates was dependent on an infectious virus genome, the cell type tested, and the passage history of the virus. In contrast to the in vitro results, the IF- phenotype was stable in vivo, whereas passage of the IF+ virus resulted in selection against the IF+ phenotype. The phenotypic expression of interferon induction by measles virus was, therefore, controlled by complex interactions between virus and host cell factors exerted both in vivo and in vitro.

Animals↗
PubMed1980

Isolation and partial characterization of two forms of cytoplasmic nucleocapsids from measles virus-infected cells.

Two species of measles virus nucleocapsids with distinct buoyant densities were isolated from infected AV3 cell homogenates by isopycnic CsCl gradient centrifugation. The more buoyant or 'light' form of the nucleocapsid had a density of 1.26 to 1.28 g/ml, whereas the less buoyant or 'heavy' nucleocapsid species had a density of 1.30 g/ml. Analysis of the two nucleocapsid species by SDS--polyacrylamide gel electrophoresis showed that both forms possessed two phosphorylated polypeptides with mol. wt. of 69000 and 60000. The heavy form of nucleocapsid consisted solely of these two polypeptide species, while the light form of nucleocapsid had two additional associated polypeptides (VP4, mol.wt. 52000, and 45K, mol. wt. 45000). Ultrastructural and immunofluorescent studies suggest that the two isolated capsid forms represent the two morphologically distinct capsid species observed in vivo. This paper discusses the possible relationship between the two capsid forms and assembly of the virus.

Amnion↗
PubMed1980

Quantification of plasminogen activator activity associated with herpesvirus-transformed cells.

Herpesvirus-transformed cell lines were examined for plasminogen activator (PA) activity using a quantitative assay. Previous results of cold fibrin overlay assays indicated that herpesvirus-transformed hamster cell lines produce fibrinolytic activity. Quantification of this activity involved the use of an 125I-fibrin lysis assay in which medium previously incubated with transformed or normal cells was tested for its ability to lyse 125I-fibrin polymers. This assay indicated an enhanced production of plasminogen-dependent fibrinolytic activity by transformed hamster cells compared to hamster embryo fibroblasts. The kinetics of secretion failed to reveal a significant difference in plasminogen activator activity in cells transformed by either herpes simplex virus types 1 or 2 (HSV-1 or HSV-2); however, transformed cells exhibited a significant increase in activity over non-transformed cells. Further characterization of PA activity associated with cells transformed by HSV-1 or HSV-2 has revealed that the protease is secreted and can function extracellularly. Extracellular PA activity produced by HSV-transformed cells is detected more efficiently than the cell-associated enzyme. Extracellular PA can be induced in two different species of cells by infection with partially inactivated HSV-2. Lytic infection of human embryo lung cells by HSV-2 strain 333 did not enhance activity, but infection of these cells with virus inactivated by u.v. irradiation resulted in increased PA levels from the cells. Increased enzyme levels were also detected in hamster embryo fibroblasts infected with partially inactivated virus. Further investigation of this enzyme function may determine whether increased levels of protease will indicate oncogenic transformation in vitro by herpesviruses.

Animals↗
PubMed1980

Leukaemia reactivates mouse cytomegalovirus.

An established model for latency by mouse cytomegalovirus (MCMV) was used to assess the effects of leukaemia on reactivation of MCMV. After inoculation of 400 spleen focus-forming units of Friend leukaemia virus (FLV), a significant number of mice yielded MCMV in salivary glands and kidneys 4 to 5 weeks later. Administration of cyclophosphamide during FLV infection increased the percentage of MCMV-positive animals. These results suggest that cytomegalovirus infections in leukaemic patients may reactivate as a result of the leukaemia itself and may be exacerbated by chemotherapy.

Animals↗
PubMed1980

Acute cytomegalovirus infections in leukemic mice.

Mice infected with 2 x 10(3) plaque-forming units of mouse cytomegalovirus (MCMV) 3 days after receiving 300 to 400 spleen focus-forming units of Friend leukemia virus developed a more severe MCMV infection than did normal animals. Increased severity was demonstrated by the increased amounts of MCMV recoverable from the salivary glands of leukemic mice 1 to 5 weeks postinfection. In addition, the difference in the number of virus isolations from the kidneys, spleens, livers, and lungs of animals (74 to 120) coinfected with MCMV and Friend leukemia virus compared with animals (49 of 120) infected with MCMV alone was significant (P less than 0.01). Both the 50% lethal dose and 50% infectious dose of MCMV in leukemic mice were lower than in normal animals. MCMV and Friend leukemia virus appear to interact by suppressing the ability of infected spleen cells to respond to mitogen-induced stimulation. The observations of increased severity of MCMV infections in leukemic mice closely parallel the situation observed in human leukemia patients who are at an increased risk of disease due to human cytomegalovirus infections. This mouse model may be useful in assessing the effect of antiviral (cytomegalovirus) therapy.

Animals↗
PubMed1980

Identification of the herpes simplex virus DNA sequences present in six herpes simplex virus thymidine kinase-transformed mouse cell lines.

We have used a novel filter hybridization approach to detect and map the herpes simplex virus (HSV) DNA sequences which are present in four HSV thymidine kinase (HSVtk+)-transformed cell lines which were derived by exposure of thymidine kinase negative (tk-) mouse cells to UV light-irradiated HSV type 2 (HSV-2). In addition, we have mapped the HSV-1 DNA sequences which are present in two HSV-1tk+-transformed cell lines produced by transfection of tk- mouse cells with sheared HSV-1 DNA. The results of these studies can be summarized as follows. (i) The only HSV DNA sequences which were common to all HSVtk+-transformed cells were those located between map coordinates 0.28 and 0.32. Thus, this region contains all of the viral DNA sequences which are necessary for the expression of HSV-mediated tk transformation. (ii) Many of the cell lines also contained variable amounts of non-tk gene viral DNA sequences located between map coordinates 0.11 to 0.57 and 0.82 to 1.00, suggesting that incorporation of the viral DNA sequences located between these map coordinates is a relatively random event. (iii) The viral DNA sequences located between map coordinates 0 to 0.11 and 0.57 to 0.82 were uniformly absent from all of the HSVtk+ cell lines tested, suggesting that there is a strong negative selective pressure against incorporation of these viral DNA sequences.

Animals↗
PubMed1980

Inhibition of herpes simplex virus type 2-induced biochemical transformation by interferon.

The effect of interferon on the biochemical transformation of thymidine kinase-deficient cells by UV-inactivated herpes simplex virus type 2 has been studied. Transformation was much less sensitive to the action of interferon than virus multiplication. However, the continuous presence of a high dose of interferon (2,000 U) inhibited transformation almost completely. Although we could not differentiate between the effect of interferon on fixation and expression of the virus thymidine kinase gene, data suggest that the inhibitory effect of interferon on transformation might be partially due to the suppression of virus thymidine kinase expression.

Animals↗
PubMed1980

Biochemical transformation by temperature-sensitive mutants of herpes simplex virus type 1.

Biochemical transformation assays of herpes simplex virus type 1 temperature-sensitive (ts) mutants distinguished three groups of mutants with regard to their thymidine kinase (TK) transforming ability: those incapable of transferring the TK gene at either the permissive or restrictive temperatures (group I); those resembling the wild-type virus, and therefore able to transform at both the permissive and nonpermissive temperatures (group II); and those that failed to transform or exhibited very low transformation frequencies at the permissive temperature but were able to transform at the nonpermissive temperature (group III). Two mutants in group II exhibited greatly enhanced transformation efficiency at the permissive temperature. The ts lesions in the majority of the mutants tested map between 0.30 and 0.60 units on the viral genome. Mutants with TK-positive (TK+), but DNA-negative, phenotypes at the nonpermissive temperature produced no TK+ transformants at the permissive temperature and only unstable transformants at the nonpermissive temperature. This suggests that a function which is required for viral DNA synthesis is also required to obtain stable expression or to transfer the TK+ gene or both when transfer is mediated by the entire viral genome.

Cell Line↗
PubMed1980

Acycloguanosine treatment of herpesvirus infections in footpads and nervous tissue of normal and immunosuppressed mice.

Treatment of herpes simplex virus type 1 (HSV-1)-infected mice with acycloguanosine resulted in significantly fewer virus isolates from nervous tissues than from tissues of untreated animals. Acycloguanosine also significantly reduced the mean titers of HSV-1 recovered from the footpads of drug-treated animals. The anti-herpetic activity of acycloguanosine was observed in both normal and immunosuppressed mice.

Acyclovir↗
PubMed1980

Expression of type-common envelope antigens by herpes simplex virus type 2-transformed hamster cells.

At least ten polypeptides were detected on the surface of the herpes simplex virus type 1 (HSV-1) virion. Two of these polypeptides, having molecular weights of 30,000 and 33,000, were identified in two herpes simplex virus type 2-transformed cell lines (333-8-9 and 333-2-29) by immunoprecipitation and SDS-PAGE. The same two virion polypeptides previously were shown to be present in an HSV-1-transformed cell line (14-012-8-1, T-10). These observations suggest that genetic information coding for these polypeptides is in close proximity to that portion of the virus genome involved in transformation.

Animals↗
PubMed1980

Herpesviruses and prostate carcinogenesis.

Prostatic cancer cell cultures possessed intracellular immunofluorescent antigens specific for human cytomegalovirus (CMV) but produced no infectious virus particles. Norman human prostatic tissue yielded a CMV isolate that transformed primary human embryo lung cells in vitro. These cell transformants were highly oncogenic when transplanted to athymic nude mice. Immunological studies revealed that sera from prostatic cancer patients reacted significantly more frequently with CMV-related antigens than sera from age-, race-, and socioeconomic status-matched benign prostate hyperplasia groups. Specific reactivity against CMV-transformed cells of lymphocytes from prostatic cancer patients was also detected. These complex findings indicate that CMV may be involved in the development of prostatic neoplasia.

Animals↗