Showing papers on "Virus published in 1977"

Continuous growth and differentiation of human myeloid leukaemic cells in suspension culture.

Abstract: ATTEMPTS to develop long-term suspension cultures of human myeloid leukaemic cells have met with limited success. Lymphoblastoid lines carrying the Epstein–Barr virus genome occasionally arise during such attempts but these lymphoid cells originate from contaminating B lymphocytes and not from the leukaemic myeloid cells1. A line established from the pleural fluid of a patient with chronic myeloid leukaemia in blast crisis2 (designated K-562) has no B-cell or T-cell markers3–4 and does not seem to be of lymphoid origin4. Its lack of morphological and histochemical differentiation2–4, however, makes it difficult to determine whether these cells are derived from myeloblasts or more primitive stem cells4. Another less documented cell line (8261) derived from the peripheral blood of a patient with acute myelogenous leukaemia showed apparent morphological and functional differentiation in agar in the presence of a feeder layer of peripheral blood leukocytes but did not differentiate in suspension culture5. Our laboratory previously reported that cultures of differentiating myeloid leukaemic cells can be maintained for several months in suspension culture but only when enriched with conditioned media (CM) from certain monolayer fibroblastic cultures of first trimester whole human embryos (ref. 6 and Ruscetti et al. in preparation). We describe here for the first time the derivation from myeloid leukaemic cells of a leukocyte culture that by morphological and histochemical criteria clearly and persistently differentiates along the myeloid series without an exogenous source of conditioned medium.

Long term culture of tumour-specific cytotoxic T cells.

Abstract: MANY investigators have been successful in the maintenance of long term tissue culture of human bone marrow-derived (B) cells. These cell lines have been established from both normal subjects1 and from patients with lymphoproliferative disorders2. In most cases, long term B-cell lines have been shown to harbour the Epstein–Barr virus genome which some investigators feel is required for establishment and maintenance of long-term cultures3. There are fewer reports describing continuous culture of human thymus derived (T) cell lines, and when successful, the lines have only been established from patients with acute lymphocytic leukaemia4. Although these cell lines have been shown to bear surface markers of normal human T lymphocytes, there have been no reports which suggest that they possess the ability to respond to immunologic stimuli or to differentiate into antigen-specific lymphocytes. Cytotoxic murine T cells have been kept in continuous culture only through repetitive mixed-lymphocyte stimulation5. In contrast to long term human lymphocyte lines, these cells proliferated only when stimulated with allogeneic lymphocytes and eventually died after a few weeks in culture. Morgan, Ruscetti and Gallo recently reported a method by which medium conditioned by phytohaemagglutinin-stimulated normal human lymphocytes allowed for the selective long-term growth of normal T cells6. In contrast to the previously mentioned cell lines, the proliferation of these reported T-cell cultures was totally dependent on the presence of an exogenously-produced growth factor supplied by the conditioned medium. In this report we describe an adaptation of this method which allows the long term culture of antigen-selected cytotoxic T cells which continue to demonstrate high levels of syngeneic tumour-specific cytotoxicity after more than 4 months in culture.

Dengue viruses and mononuclear phagocytes. I. Infection enhancement by non-neutralizing antibody.

Abstract: Cultured mononuclear peripheral blood leukocytes (PBL) from nonimmune human beings and monkeys are nonpermissive to dengue 2 virus (D2V) infection at multiplicities of infection of 0.001-0.1, but become permissive when non-neutralizing dengue antibody is added to medium. D2V infection occurred in PBL prepared from anti-coagulated but not from defibrinated plasma. Infection enhancement was produced by multiple lots of heterotypic anti-dengue raised in several mammalian species. Homotypic anti-dengue neutralized D2V at high concentrations but enhanced at low concentrations; enhancement end point in one serum was 1:320,000. The infection-enhancing factor was a noncytophilic antibody of the IgG class. D2V infection occurred in the absence of heat-labile complement components but did not occur when complexes were prepared with anti- dengue F(ab)(2). Treatment of PBL with several proteases increased permissiveness to D2V infection by immune complexes but not by virus alone. Two rhesus monkey serums collected 14 days after D2V infection contained an IgG antibody with high-titered enhancing activity but with no hemagglutination-inhibition or neutralizing activity. Virus-antibody complexes are irreversibly attached to PBL within 15 min and completely internalized in 60 min. There was considerable variation in cellular infection in different experiments, however, maximum virus yields usually exceeded 1,000 plaque-forming units per 1 x 10(6) PBL occurring between 2 and 4 days in culture. In vitro antibody-dependent infection of PBL provides a possible model for study of pathogenetic mechanisms in infants with dengue shock syndrome who passively acquire maternal anti-dengue IgG.

Antibody-enhanced dengue virus infection in primate leukocytes

Abstract: DENGUE viruses, types 1–4, are arthropod-borne flaviviruses which cause dengue shock syndrome (DSS) in humans possessing pre-infection antibody, passively acquired or derived from heterotypic infection1. Although the immuno-pathological mechanism of DSS is not fully understood, experimental studies suggest that dengue virus production is immunologically regulated. Monkeys with monotypic immunity to dengue types 1, 3 or 4 viruses, when challenged with dengue 2, had significantly higher levels of circulating virus than did similarly infected susceptible animals2. This may be attributable to the replication of virus in leukocytes. In infected monkeys, virus was frequently recovered from buffy coat cells and from lymphatic tissues3. The role of leukocytes in enhanced infection is further supported by the observation that dengue replicates readily in cultures of peripheral blood leukocytes (PBL) prepared from immune simian or human donors, but poorly or not at all in leukocytes from non-immune hosts4–6. Studies on the immunological specificity of this phenomenon have been hindered by the requirement either for expensive experimental hosts (monkeys) or for human donors with chronologically defined dengue infections. Here we describe the in vitro enhancement of dengue infection in PBL by antibody. This system provides a provisional model for DSS in young infants during primary dengue infections7,8.

Polyclonal Ig production after Epstein-Barr virus infection of human lymphocytes in vitro

Abstract: APART from the specific anti-Epstein-Barr virus (EBV) response in infectious mononucleosis (IM), there is a strong general increase of antibody levels1. The major increase comprises IgM. As EBV has been shown to infect B lymphocytes selectively2 we hypothesised that the virus triggered the infected cells to release immunoglobulin, much like the effect of certain B-cell mitogens3, although the mechanism of activation must be different. It is known that EBV infection in vitro of human blood lymphocytes gives rise to increased DNA synthesis4 and that lymphoid cell lines carrying the EBV genome shed or release immunoglobulins5 of various classes. Furthermore, the IgM increase seen in IM would fit with a polyclonal B-cell activation (PBA) of EBV as PBA usually gives rise to IgM secretion6. To test this hypothesis, we have exposed lymphocytes from cord blood and adult peripheral blood to EBV in vitro and measured the released IgM, by a doubleantibody radioimmunoassay, and individual antibody-forming cells (PFC) against haptenated red blood cells and sheep red blood cells (SRBC).

Biochemical evidence that MCF murine leukemia viruses are envelope (env) gene recombinants.

Abstract: Recently, a novel class of murine type C virus (MCF), some strains of which are highly oncogenic in the AKR acceleration test, has been isolated from premalignant and malignant thymuses of AKR mice. The biology of these viruses suggested that MCFs are the product of recombination between endogenous ecotropic and xenotropic viruses and, further, that the recombination has taken place within the envelope (env) gene which encodes the surface glycoprotein (gp70) of the virion. We have compared by tryptic peptide analysis, the gp70s of four MCF isolates with the gp70s of various possible parental viruses. In addition, we have compared the tryptic peptides of the gag gene products p30 and p15 from several of these viruses. The results allow the following conclusions: (i) the gp70s of the MCF viruses are not identical to one another and are different from the gp70s of the possible parental viruses tested; (ii) the MCF virus gp70s have tryptic peptides in common with xenotropic virus gp70s as well as with ecotropic virus gp70s; and (iii) the gap region protein, p30, of the MCFs tested is identical to p30 of AKR ecotropic virus (Akv-1 or Akv-2) and distinct from p30 of xenotropic viruses, suggesting that the 59 end of the recombinant viruses is of Akv origin. The findings are discussed with respect to the possible role a recombinant virus might play in leukemogenesis in AKR mice.

The natural history of recurrent herpes simplex labialis: implications for antiviral therapy.

Abstract: We performed daily examination of 80 patients with recurrent herpes simplex labialis to define the course of the disease and to identify quantitative and objective measurements for use in monitoring the efficacy of antiviral chemotherapy. Pain, lesion size, mean virus titers from lesion swabs (10(5) plaque-forming units [PFU]) and frequency of virus-positive lesions (89 per cent) were maximal during the first 24 hours and decreased thereafter. Lesion punch-biopsy virus titers increased from a mean of less than 10(1) PFU in the prodromal and erythema stages to a mean of 10(4.7) in the vesicle stage. MEasurements potentially useful in monitoring antiviral efficacy include: time to loss of crust, time to complete healing, intensity and duration of lesion pain, area defined by lesion virus titer and duration of lesion virus excretion, and maximum lesion virus titer after the first visit. Early application of topical antiviral therapy should theoretically be able to alter the course of this disease.

A case of Ebola virus infection.

Abstract: In November 1976 an investigator at the Microbiological Research Establishment accidentally inoculated himself while processing material from patients in Africa who had been suffering from a haemorrhagic fever of unknown cause. He developed an illness closely resembling Marburg disease, and a virus was isolated from his blood that resembled Marburg virus but was distinct serologically. The course of the illness was mild and may have been modified by treatment with human interferon and convalescent serum. Convalescence was protracted; there was evidence of bone-marrow depression and virus was excreted in low titre for some weeks. Recovery was complete. Infection was contained by barrier-nursing techniques using a negative-pressure plastic isolator and infection did not spread to attendant staff or to the community.

Generation of both cross-reactive and virus-specific T-cell populations after immunization with serologically distinct influenza A viruses.

Abstract: Specificity of cytotoxic T-cell function was investigated for a range of different influenza viruses T cells from mice immunized with A or B strain influenza viruses, or with vaccinia virus, showed reciprocal exclusion of cytotoxicity Extensive cross-reactivity was, however, found for lymphocyte populations from mice infected with a variety of serologically distinct influenza A viruses, though serum antibodies did not cross-react when tested in a radioimmunoassay using comparable target cells as immunoadsorbents This apparent lack of T-cell specificity was recognized for immune spleen cells generated after intraperitoneal inoculation of high titers of virus, and for mediastinal lymph node populations from mice with pneumonia due to infection with much less virus The phenomenon could not be explained on the basis of exposure to the chicken host component, which is common to A and B strain viruses However, not all of the virus-immune T-cell clones are cross-reactive Competitive-inhibition experiments indicate that a considerable proportion of the lymphocyte response is restricted to the immunizing virus Even so, the less specific component is significant Also, exposure to one type A virus was found to prime for an enhanced cell-mediated immunity response after challenge with a second, serologically different A strain virus

Rabies virus glycoprotein. II. Biological and serological characterization.

Abstract: Purified rabies virus glycoprotein (G) was shown by complement fixation and immunodiffusion tests to be a second distinct antigen of the virus. It it the only structural protein of the virus that induces the formation of virus-neutralizing antibodies and which confers immunity to animals. When the G protein is taken as antigen, the complement fixation test can be used for the assay of virus-neutralizing antibodies. The total protective activity of the virus was recovered in the purified G protein preparation. The protective activity of G protein increased with purification: 9 ng of G protein was required to protect 50% of the mice as compared to 1.63 micrograms of the virus. Selective immunofluorescent membrane staining and immunocytolysis of rabies virus-infected cells were shown to be G protein specific. Due to its purity and potency, the G protein preparation can be considered the ideal human antirabies vaccine.

Cell Transformation by RNA Tumor Viruses

Abstract: Along with other carcinogens of physical or chemical origin, viruses are known to be associated with and to cause tumors in a variety of experimental animals. RNA tumor viruses in particular are widespread in many species of animals, and frequently cause sarcomas or leukemia. The isolation of fowl sarcoma-leukemia virus in the early 1910s by a number of investigators marked the first successful identification of such tumor viruses (Ellermann and Bang, 1909; Rous, 1911; Fujinami and Inamoto, 1914). The cell-virus systems used for the studies of basic aspects of the pathogenesis of avian tumor viruses illustrate the progress in methodology for studying animal viruses in general. Early work in animal hosts was gradually replaced by a system using the chorioallantoic membrane of eggs (Keogh, 1938), then by tissue culture cells (Manaker and Groupe, 1956). The establishment of an assay system for Rous sarcoma virus (RSV) in tissue culture cells (Temin and Rubin, 1958) eventually led to an era of quantitative studies on the mechanism of cellular alteration by viruses.

Isolation of transforming murine leukemia viruses from mice with a high incidence of spontaneous lymphoma

Abstract: Murine leukemia viruses capable of malignant transformation of mink tissue culture cells have been isolated from an AKR thymoma cell line and from a spontaneous reticulum cell sarcoma in an NIH Swiss mouse partially congenic for the AKR ecotropic virus-inducing locus Akv-2. In contrast to the recently described mink cell focus-inducing strains of murine leukemia virus, at least one of the two transforming strains is replication defective. Nonproducer mink cells carrying the genome of the transforming virus of AKR origin have been isolated, and pseudotype transforming viruses generated.

HLA restriction of cell-mediated lysis of influenza virus-infected human cells.

Abstract: MURINE T lymphocytes that mediate the lysis of virus-infected cells show specificity both for the viral cell surface antigens and for the H–2K or D antigens of the major histo-compatibility complex1–8. The cytotoxic T lymphocytes and the target cell must share H–2K or D products. The experiments reported here demonstrate that there is a similar requirement for partial HLA identity between human cytotoxic lymphocytes and influenza virus-infected target cells.

Cell fusion induced by herpes simplex virus is promoted and suppressed by different viral glycoproteins

Abstract: Some of the factors that regulate membrane fusion resulting in polykaryocyte formationhave been investigated, using the model system of human cells infected with mutants of herpes simplex virus (HSV). One of the mutant viruses used in this study (MP) failed to produce the viral glycoprotein designated C2--a nonlethal defect that has previously been correlated with the polykaryocyte-inducing phenotype of this and other mutant strains (wild-type strains of HSV usually induce the aggregation of infected cells rather than their fusion). The other mutant virus (tsB5), a temperature-sensitive conditional-lethal mutant, failed to produce glycoprotein B2 at non-permissive temperature, whereas the synthesis of all other viral products appeared to be normal. We produced and isolated seven recombinants of MP and tsB5 that expressed both of the parental alterations in glycoprotein synthesis. All of the re-combinant viruses induced the fusion of infected cells at 34 degrees (correlated with the absence of C2 expression) but were unable to cause cell fusion at 39 degrees (correlated with the absence of C2 and of B2 expression), even after infection at multiplicities high enough to ensure that all cells in the cultures synthesized viral macromolecules. These results and studies on the dominance or recessiveness of the fusion-inducing phenotype in mixed infections provide evidence that glycoprotein B2 plays a critical role in the promotion of cell fusion and that glycoprotein C2 can act to suppress fusion.

Cytology of gynecologic condyloma acuminatum.

Abstract: The morphology of certain cell types often encountered in vaginal and cervical smears of condyloma patients are described. These cells, considered to be exfoliated from epithelium affected by condyloma virus, were found in 60 per cent of the smears obtained from 192 women with condylomatat acuminata. Dysplasia of the cervical and vaginal epithelium is frequently associated with condyloma. Structural features typical of the condylomatous epithelium were common in these dysplasias. These lesions are probably also due to infection by condyloma virus, yet their significance is unknown and the possibility of a precancerous status cannot be ruled out except by a very long term follow-up study which is in progress. It may be assumed that this virus may affect the cervical and vaginal epithelium without any typical papillary condylomatous lesions resulting. Even in the absence of typical condylomatous papillary formations, the cytologic findings may reveal condyloma infection.

Enhancement of IgE-mediated histamine release from human basophils by viruses: role of interferon.

Abstract: Human leukocytes maintained in culture are induced to release histamine when exposed to ragweed antigen E or anti-IgE. Leukocyte cultures incubated with virus (i.e. HSV-1, Influenza A, and Adeno-1) but not exposed to ragweed antigen E or anti-IgE fail to release histamine. If, however, leukocyte cultures are first exposed to virus and then to ragweed antigen E or anti-IgE, significant enhancement of histamine release occurs. Both infectious and inactivated virus enhance histamine release and the degree of enhancement is related to the concentration of virus and the length of the incubation. Tissue culture fluid harvested 8 h after exposure of leukocytes to virus contains a soluble factor which is capable of enhancing histamine release when added to fresh leukocyte cultures. This factor has all the properties of interferon including species specificity and cannot be dissociated from the antiviral activity of interferon. Moreover, both known inducers of interferon (poly I:poly C) and standard preparations of interferon are capable of enhancing histamine release. The enhancement of histamine release by interferon represents a new biological role for interferon.

Cytotoxic T cells kill influenza virus infected cells but do not distinguish between serologically distinct type A viruses

Abstract: THE molecular basis of recognition and target cell killing by cytotoxic T cells is still unknown. Doherty and Zinkernagel showed that mouse cells infected with lymphocytic choriomeningitis virus can be lysed by immune cytotoxic T cells but only if both cell types share at least part of the major histocompatibility (H–2) region (see ref. 1). H–2 compatibility is also required for cell killing in other viral systems2–4, and for cells carrying non-viral antigens5–7. Our aim is to analyse the virus specificity of cytotoxic T cells, and the nature of their antigen recognition units. This requires a virus system with a small number of well characterised protein components, amenable to biochemical and genetic manipulation, as well as cytotoxic cells that will lyse target cells in a short term assay to minimise nonspecific cytotoxicity. Influenza virus offers many advantages for this type of study. The virion contains only two well characterised surfaced antigens, haemagglutinin (H) and neuraminidase (N), that are also expressed on the surface of infected cells8–11, and can be purified in quantity. Virus strains are available with serologically distinct surface proteins, and with different internal proteins12,13. Here we describe the generation of potent cytotoxic cells that are specific for histo-compatible influenza virus-infected cells, but exhibit extensive cross-reactivity between the different type A influenza virus strains.

Glucocorticoid-stimulated accumulation of mouse mammary tumor virus RNA: increased rate of synthesis of viral RNA

Abstract: Glucocorticoid hormones specifically increase the intracellular concentration of mouse mammary tumor virus (MMTV) RNA in a cultured cell line from a GR mouse mammary carcinoma (GR) and in an MMTV-infected rat hepatoma cell line (M1.19). In contrast, these steroids have no effect on the concentration of MMTV RNA in a lymphoma line, S49, from a Balb/c mouse. Using a molecular hybridization procedure to detect newly synthesized RNA, we have directly measured the effect of dexamethasone, a synthetic glucocorticoid, on the rate of MMTV RNA synthesis. In GR cells the hormone causes a 10-fold increase in the rate of synthesis of viral RNA without appreciably affecting the overall rate of cellular RNA synthesis. The transition from the basal to the maximally stimulated rate of MMTV RNA synthesis occurs within the earliest labeling period, 0-15 min after addition of the hormone. Thus, it appears that glucocorticoids regulate MMTV genes principally by this rapid and specific alteration of their rate of transcription. Similar results are obtained in M1.19 rat hepatoma cells. In contrast, dexamethasone does not affect the rate of viral RNA synthesis in S49 lymphoma cells.

Clonal transformation of adult human leukocytes by Epstein-Barr virus.

Abstract: We have developed a clonal transformation assay for Epstein-Barr virus which uses adult human leukocytes as target cells. The target cells were isolated from Epstein-Barr seronegative donors, and the same donor's cells could be studied repeatedly over long periods of time. When these cells were transformed by Epstein-Barr virus and had proliferated sufficiently to be studied, they had an average cloning efficiency of 3%. Assuming this average cloning efficiency obtains at the onset of transformation, we calculate that transformation by Epstein-Barr virus leads to immortalization maximally of about 1 in 30 of the adult peripheral leukocytes exposed to the virus. Studying the number of colonies transformed as a function of the amount of virus to which the cells are exposed indicates that a single DNA-containing virus particle is sufficient to transform a cell. All of the transformed clones studied harbored viral DNA. This technique will now permit, for the first time, our studying clonal variations in adult peripheral leukocytes transformed by Epstein-Barr virus as a function of input multiplicity of the virus and of the donor's immune status.

Genetics of RNA Tumor Viruses

Abstract: The genetic analysis of RNA tumor viruses has two main objectives: (1) to provide an understanding of virus replication and (2) to explain virus-induced transformation of the host cell. Virus replication results from a complex interaction of viral and cellular genomes. Viral genetics, however, considers only the virus side of this interaction; the numerous and specific cellular functions which are required for the synthesis of infectious virus will have to be defined by a genetic analysis of the host cell. In virus-induced transformation, viral genetic information presumably interferes with the genetic regulatory apparatus of the host cell, and here again it is important to realize that focusing on the viral information will reveal only part of a very complex interaction between two organisms. Despite these obvious limitations, the viral genome is at the moment that partner in this interaction which is more amenable to experimental study and offers realistic opportunities for an increase of our insight into virus replication and cellular transformation.

Suppression of in vitro Epstein-Barr virus infection. A new role for adult human T lymphocytes.

Abstract: Studies have been performed on in vitro infection by Epstein-Barr virus (EBV) of subpopulations of human lymphocytes. B cells of adult peripheral or fetal cord blood transform with equal efficiency, whether assayed by DNA synthesis induction or by outgrowth of transformed lymphocytes. In contrast, unfractionated adult lymphocytes transform much less efficiently than those from fetal cord. Reconstitution experiments of different cell preparations indicated that this difference was due to a suppression of B-cell proliferation by adult Ig-negative lymphocytes which fetal Ig-negative lymphocytes were unable to perform. Separation of Ig-negative lymphocytes into various subpopulations revealed that the suppression was performed by T cells. Macrophages and null cells play little or no role in suppression. The relevance of this phenomenon to infection and recovery from EBV infection during and after infectious mononucleosis is discussed.

Aphids As Virus Vectors

Abstract: What do you do to start reading aphids as virus vectors? Searching the book that you love to read first or find an interesting book that will make you want to read? Everybody has difference with their reason of reading a book. Actuary, reading habit must be from earlier. Many people may be love to read, but not a book. It's not fault. Someone will be bored to open the thick book with small words to read. In more, this is the real condition. So do happen probably with this aphids as virus vectors.

Cellular immunity and herpesvirus infections in cardiac-transplant patients.

Abstract: We observed severe infection with herpes simplex virus in cardiac-transplant patients despite their high serum antibody levels to this virus. Therefore, we sought to correlate clinical susceptibility to two herpesvirus (simplex and zoster) infections with specific cellular immunity, assessed by the transformation and interferon responses of peripheral blood mononuclear cells to heat-inactivated antigens. Transformation and interferon response to herps simplex virus was maximally depressed immediately after transplantation, the time when severe and prolonged infection with herps simplex virus occurred. Six months to six years after transplantation, both clinical susceptibility and cellular immunity to herpes simplex virus were normal. Herpes zoster infections were more frequent than normal at all times after cardiac transplantation; depressed or absent cellular responses to the varicella zoster virus paralleled that susceptibility. In these patients the risk of severe herpesvirus infections correlated with depressed cellular immune responses to the specific viral agent involved.